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11 December 2010
Author: Giorgos Lazaridis
Long Range (10mt) IR Beam Break Detector

The Receiver

Testing the circuit on a breadboard

The receiver circuit is based on the TSOP1838 chip. It has an integrated PIN diode and a preamplifier circuit inside the chip. Moreover, the epoxy package is an IR filter by itself, that blocks other light sources beyond IR spectrum. This makes it very reliable, and also the output of the chip is rectangular pulses that can be driven directly to a microcontroller. This chip saves the designer of the circuit (that will be me :D) from a lot of dirty job to design filters and Schmitt Triggers... Here is the (simplified) schematic diagram: (click to enlarge)

The TSOP1838 does the dirty job

The TSOP1838 does the dirty job. It "reads" the modulated IR pulses from the transmitter circuit, and converts it into pulses. So what someone would expect to see directly at the output of this chip, is rectangular pulses with 32 Hz frequency, and 1.5-1.6 mSec positive pulse duration. I pass these pulses through a current amplifier transistor (T1) and then directly to the reset input of the Decade Counter (4017 CMOS). So, whenever a pulse arrives, the counter resets. Keep this in mind for later use.

This was the first part of the receiver. The second part, is the 555 timer. This is connected as an astable multivibrator with variable frequency, controlled with the potentiometer R6. As a matter of fact, the parts around the 555 are carefully selected so that the minimum and maximum frequency will be 3 (minimum) to 8 (maximum) times more than the frequency of the transmission pulses (32 Hz). These pulses are then driven to the clock input of the 4017 counter.

Suppose now that the IR pulses arrives normally at the IR receiver chip, and are normally driven to the reset of 4017. And also, the clock pulses from the 555 normally arrives at the clock of the 4017. What happens? Well, the 4017 increases its count on every 555 pulse, but resets on every IR pulse. And due to the fact that the 555 pulses can be maximum 8 time faster than the IR pulses, this means that the 9th output (Q9 - Pin 11) of the 4017 will NEVER become 1.

But if something breaks the IR beam, then there will be no more reset pulses to the 4017, and eventually the 9th output will become 1! At that point, a positive feedback from the 9th output will be driven to the Clock Enable (ENA Pin 13) of the 4017. This will PREVENT any other pulse from the clock to change the chip's count. So the 9th output will remain HIGH, as long as the beam is broken.

But if you notice, the 9th output also drives the T2 transistor, which controls our load (Relay, Siren, Buzzer etc)... Guess what! Upon a beam break, the load will be armed! Easy it is not?

So, here are some screenshots from the oscilloscope:

The yellow channel shows the 555 pulses, and the green comes from the IR receiver. In minimum frequency, the 555 produces approximately 3 pulses per one pulse of the IR transmitter. In maximum frequency, the 555 produces approximately 8 pulses per one pulse of the IR transmitter.

What is the reason of changing the 555 frequency?

You could name this potentiometer "sensitivity" or "threshold", or another fancy name. Why? Suppose that you have set the 555 to minimum frequency (pot at maximum resistance). To set output 9, there have to arrive 9 pulses at the clock input. But if the 555 produces 3 pulses per 1 IR pulse, this means that the obstacle has to remain at least for 3 IR pulses. That sounds much, but if you consider that each pulse has about 31 mSec delay, this means that the obstacle has to remain at least 93 mSec... That is 1 tenth of a second

At maximum 555 frequency, the obstacle has to remain for one full IR pulse plus 1/9 of it. That is 31 mSec + 3.4 = about 35 mSec. After 35 mSec, the load will be activated.

The reason i added this pot is simple. In close distances and in environments with not particular ambient noise, high sensitivity can work just fine. But if you operate this circuit in long ranges - almost the maximum range of the IR LED- and in harsh environments, you need to decrease the sensitivity to avoid false triggering. In case that the circuit still gives false triggers, you may need to use a larger potentiometer, 50 K for example, to further reduce the sensitivity. Don't over do it. You don't want the obstacle to remain 1-2 seconds until the load is activated, do you?...

Bill Of Materials - Receiver
R1Resistor 100 Ohm 1/4 Watt 5% Carbon Film 
R2Resistor 1 KOhm 1/4 Watt 5% Carbon Film 
R3Resistor 330 Ohm 1/4 Watt 5% Carbon Film 
R4Resistor 1 KOhm 1/4 Watt 5% Carbon Film 
R5Resistor 2.2 KOhm 1/4 Watt 5% Carbon Film 
R610 K potentiometer
R7Resistor 10 KOhm 1/4 Watt 5% Carbon Film 
C1Electrolytic Capacitor 1 uF 50 Volts
C2Electrolytic Capacitor 4.7 uF 50 Volts
C3Electrolytic Capacitor 1 uF 50 Volts
T1BC337 NPN Silicon AF Transistors 
T2BC548 Switching and Applications NPN Epitaxial Transistor 
D11N4004 General Purpose Diode Rectifier 
Integrated Circuits
IR1TSOP1838 38 KHz Photo Modules for PCM Remote Control Systems 
IC1555 Timer 
IC2CD 4017 Decade Divider/Counter 
IR15V low coil current relay



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  • At 13 January 2016, 21:09:09 user Phil wrote:   [reply @ Phil]
    • Hello Giorgos, and firstly thank you very much for sharing this circuit.
      I built it and it works a treat. I have a range of about 5m indoors and not yet tested it outdoors. The IR led I used was "Night Vision 5mm 180mW 12 degree 875nM IR LED's Qty 10 New Vishay TSHA5202" from eBay item number:121675391460.
      This seems to be quite a powerful led so I would be interested to know how it would be possible to increase the power to this led in the cct.
      The output waveform at the led shows a 1.52V peak to peak, and a rms value (calculated by the scope) of 355mV.
      The ideal DC voltage for this led seems to be 1.2V, do you think we could push the RMS value up to closer to 1.2V, say perhaps 1V ?
      Anyway good fun, and I shall do some more testing over the next few days.

  • At 16 December 2015, 16:04:11 user Mobi wrote:   [reply @ Mobi]
    • Hello, I am aiming to make an IR transmitter for a range of 3-4 meters, can you plz help me out?

  • At 8 October 2015, 1:39:48 user Edward wrote:   [reply @ Edward]
    • @Giorgos Lazaridis
      can it able to detect movement with 1.7ms pulse ?

  • At 18 August 2015, 23:51:46 user Omar Milano wrote:   [reply @ Omar Milano]
    • @Giorgos Lazaridis
      Hi Giorgos
      I need a person to develop some equipments for me with that technologie.
      Do you think can you help me with that?

      Let me know please

      USA 1 (786) 603.57.48

  • At 13 March 2015, 14:38:31 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @andreas too long for these parts, you need more power

  • At 13 March 2015, 10:02:11 user andreas wrote:   [reply @ andreas]
    • If the distance is more than 50 meters, how the schematic?

  • At 9 March 2015, 14:33:48 user smailo wrote:   [reply @ smailo]
    • Where the C2 connected exactly and could you please tell me how can I get the frequencies and explain how the job of each part.
      Thanks a lot.

  • At 26 February 2015, 19:13:44 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Adrian Spencer This is not an encoded signal so you cannot use multiple transmitters.

  • At 24 February 2015, 11:17:56 user Adrian Spencer wrote:   [reply @ Adrian Spencer]
    • how would you use multiple ir led and recievers?

  • At 22 February 2015, 8:08:43 user dibagay wrote:   [reply @ dibagay]
    • @Giorgos Lazaridis
      could you please post eagle files ( sch & pcb ) for this project thankfully

  • At 9 December 2014, 17:27:21 user Sanny wrote:   [reply @ Sanny]
    • Nice writing but
      How to increase ir sensor range?

  • At 16 November 2014, 14:12:05 user s b subramanian wrote:   [reply @ s b subramanian]
    • Dear sir
      i need ir proximity sensor circuit diagram for sensing distance about 40cm can i use the same

  • At 31 October 2014, 14:12:35 user KSwanson wrote:   [reply @ KSwanson]
    • I have a barn with an older automatic door opener that doesn't have a "Safety eye" for stopping/reversing the door when it is closing. If I could wire this output into the stop or reverse button (which is just a contact closure), would that work?
      Would you be able/willing to build this for me? Contact me off-list for discussion/negotiation.

  • At 22 October 2014, 7:30:59 user Michael Gani wrote:   [reply @ Michael Gani]
    • Hi Giorgos,

      First of thanks for sharing. This is indeed a great help for beginner like me to understand real world application based on the 555 IC.

      From what I know, the 555 osc freq formula should be 1 / { C * ln(2) * ( R1 2*R2 ) }.
      But, using this formula with your Resistor and Capacitor value yield 28kHz(ICA) and 41kHz(ICB) instead of 38kHz and 38Hz.

      Could you enlighten me on what formula did you use to calculated your astable oscillation frequency?

      Thank you in advance.



  • At 16 October 2014, 19:06:40 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @GRAHAM Click on the diagram to see in full size ;)

  • At 15 October 2014, 16:20:01 user GRAHAM wrote:   [reply @ GRAHAM]
    • Hello, I was interested in building your long range infra red detector, but I am finding the circuit diagram of the receiver difficult to see, it is not very clear. I would be most grateful if you would E mail me a copy.

      many thanks, Graham Creber.

  • At 24 September 2014, 17:51:40 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @gabriel nope too complicated

  • At 23 September 2014, 22:09:53 user gabriel wrote:   [reply @ gabriel]
    • Can i use this design to have say 10 transmitter and 10 receiver (triggers light from any transmitter?
      Light will be switched ON till transmitter is switched OFF?

  • At 10 September 2014, 22:28:51 user Owen wrote:   [reply @ Owen]
    • How would you design the receiver circuit for an long range ir distance measurer, using the TSOP183 chip. Also connecting it to an ADC of an microprocessor.

  • At 28 May 2014, 17:59:31 user Niranch wrote:   [reply @ Niranch]
    • Will you tell me the formula to calculate the time that LED(white) keeps lighting? (I need to use a buzzer and increase time of operation.)

  • At 27 May 2014, 15:46:17 user Niranch wrote:   [reply @ Niranch]
    • Can't we use a simple receiver circuit as in the link?


  • At 13 May 2014, 17:59:45 user ali wrote:   [reply @ ali]
    • hello , i perform the cct but the output ir from led is very poor why?
      i delete the resistor 220 ohm . but the receiver do not work true and do not receive from the transmitter kit ?

  • At 10 May 2014, 23:34:51 user soros wrote:   [reply @ soros]
    • HI thanks for good project
      after i build this , its work well around 8-9 meters , and beam of IR TX is sharp and strange not like TV remote as can reflect and bounce with wall or proof

      I test try used SONY TV remote is can control RX this project too
      when i point TX to Television and try SONY remote to control its have effect difficult to control the TV
      I think this project have effect with TV and Remote TV, not suitable use near TV.
      or you have good advise for this problem


  • At 6 May 2014, 7:43:06 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Michael wentworth Sure, if you can break it faster than the speed of light for the given distance...

  • At 6 May 2014, 7:39:13 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @dinesh kumar yes you could

  • At 25 April 2014, 15:40:34 user Tom wrote:   [reply @ Tom]
    • IC1B generates around 41kHz in this wiring (R3=6.8k, R4=22k, C1=680p)

  • At 19 April 2014, 23:23:03 user Michael wentworth wrote:   [reply @ Michael wentworth]
    • Hi Giorgos, i dont know much about IR but is it possible to have a single beam broken at various positions along the beam and the time and position/ location of the break.

  • At 12 April 2014, 14:36:32 user dinesh kumar wrote:   [reply @ dinesh kumar]
    • hello sir, i am making my final year project on wireless solar power transmission. i am using TSOP1556 as an IR reciever. can i use a LED from remote as an IR transmitter to get a range of 10m or more???

  • At 23 March 2014, 6:48:41 user muhammad mumtaz wrote:   [reply @ muhammad mumtaz]
    • Hellow Sir,
      on behalf of my recent post i got ir receiver(tsop-1738).Can i use this one instead of tsop-1838?Please reply me as soon as possible because i can't proceed on without resolving this issue.(Reply me on mumtaz.naich@gmail.com)

  • At 19 March 2014, 10:22:45 user muhammad mumtaz wrote:   [reply @ muhammad mumtaz]
    • Hellow Sir I am doing my final year project on motion detection based sequirty system and trying to design ir transmitter and receiver but the problem is that here TSOP1838 and even no other receiver of tsop series not available so what i do and what type of ir receiver i use instead of tsop-1838.Plz reply me on this email(mm_0454@yahoo.com)

  • At 30 December 2013, 8:38:15 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Abhishek No it does not help the range at all. It helps the filtering procedure (which can be distinguished from ambient noise) and also its good to transmit more data in less time.

  • At 26 December 2013, 16:34:40 user Abhishek wrote:   [reply @ Abhishek]
    • Please send me explanation about why you are modulating the signal and using high frequency? Does it helps to increase the range

  • At 12 October 2013, 9:01:16 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Kamran maybe the connection of the 1838 is not correct?

  • At 9 October 2013, 18:00:43 user Pradeep wrote:   [reply @ Pradeep]
    • @Felix Khan Hi Sir,
      I am doing my final year Engineering. I am doing a project to sense a thin wire or a thread that falls in the path of the IR beam. From your comment, i understand that your circuit will solve my purpose.
      It would be really very helpful if you can send me the circuit and its related details. My mail id is pradipma@gmail.com
      Thanks and Regards,

  • At 1 October 2013, 7:54:35 user Kamran wrote:   [reply @ Kamran]
    • Hey. I am trying to use IR1838 with the IR transmitter. But unfortunately, when i try to place IR led in front of the receiver, there is no chgange on the pin 1 of the IR 1838. But when i use the AC remote for random checking, i get a momentary zero pulse(~2.1 V). So where can i possibly wrong. The IR transmitter is just an ordinary transmitter purchased from the market. And i have generated(~37.3Khz) carrier from the micro.
      Hoping to hear from you soon.

  • At 21 September 2013, 14:16:20 user Pete wrote:   [reply @ Pete]
    • Can you do a gauge rpm meter (with lcd 2x16) on HV cables, to gasoline engine? i searching for it... i wanna to do it alone... thanks a lot!

      Guy from Poland

  • At 15 September 2013, 13:46:43 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @imran I just explained how to calculate speed from known distance. Reverse to get the time. As for the design, i'm sorry i do not design circuits on demand.

  • At 15 September 2013, 10:46:05 user imran wrote:   [reply @ imran]
    • sir actually i want to know how to calculate time which an object takes between two IR sensors having a known distance.so what timer or IC i should use in my project.how to inerface that IC with IR.I want to use this for calculating a speed of a car on the road.plz reply at imran_manzoor16aug@yahoo.com

  • At 15 September 2013, 10:27:26 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Imran Speed = meter per second (for example). So separate the two sensors by say one meter. Then have a digital counter counting 100s of miliseconds (that's 100msec per count or 10 counts per second). When the object passes through first IR beam, the counter starts, then through the second it stops. The count that you see is how many 100s of miliseconds it took for the object to travel one meter. Say you see 1500mSec (thats 1.5 seconds).

      1500 msec = 1 meter
      1000 msec = x
      x = 1 meter x 1000/1500 = 1 x 0.66 = 0.66 meters/sec

      Of kmph:
      1500 msec = 0.001 km
      3600000 msec = x
      x = 0.001 x 3600000 / 1500 = 2.4 Km/hour

  • At 15 September 2013, 10:16:35 user Imran wrote:   [reply @ Imran]
    • that work was fantastic!!!!!
      sir i want to use two infrared sensors.the distance between them is determined and known i want to calculate the time that an object takes to cover that distance.what should i do...how should i proceed...any one can help me please....
      my address id (imran_manzoor16aug@yahoo.com)
      waiting 4 reply...

  • At 30 August 2013, 16:40:26 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @jonathan twynham The angle depends on your LEDs alone. Keep in mind that wider angle results in shorter distance. Consult the LED dataseet

  • At 18 August 2013, 8:16:10 user jonathan twynham wrote:   [reply @ jonathan twynham]
    • hi.

      great circuit. will be building this shortly if it does what I hope.

      what sort of angle will the transmitter output through.. as in if I had one transmitter on a flat aurface such as a wall but needed to detect an object within a 45degree arc from the transmitter and used multiple receivers.. that way I could detect at what angle the object is at from the wall.

      could I then use another transmitter on an opposite wall with multiple receivers on the other side (basically 180degrees to each other) I could then uae it as a basic position calculator by comparing which beams are broken..

  • At 2 August 2013, 5:28:03 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Rudie Lamprecht You can increase the distance with more powerful LED transmitter indeed. As for the laser, it will not work with this circuit. Commercial mW lasers are quite safe for humans and animals as long as you do not look directly the beam

  • At 25 July 2013, 21:32:01 user Rudie Lamprecht wrote:   [reply @ Rudie Lamprecht]
    • Hi Giorgos

      Thanks for your good design. Will it be possible to go to say 30 m ? Will I need lenses or do I need to amplify the signal otherwise ?

      I have seen the 'expensive' IR beam detectors used for home security systems, that go up to 50 m but they are too expensive e.g. ~ US $ 70.

      What do you think about laser for a similar application such as the 'toy' laser pointers sold cheaply on EBay ? If I use laser can I make it safe (e.g. filter) so that it is not harmful to human or animal?

  • At 8 July 2013, 17:34:46 user david saleh wrote:   [reply @ david saleh]
    • dear sir
      isaw your model long range
      here i need this idea for usuing to not forget the child in the it happeed here 3 times
      if this circit can remaid the driver that maybe you forgot the child can save life
      is it possible to put a stop alarm in
      the remote and reniew when it has contact again in the car
      i need for car rescue
      thank you sir david

  • At 2 July 2013, 19:23:49 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Ong They are ok to use

  • At 2 July 2013, 10:15:42 user Gerhard Smith wrote:   [reply @ Gerhard Smith]
    • The following links will be available for 30 days(freepdfhosting site restriction).
      It is a PCB layout for the transmitter using surface mount parts.
      PCB mask: http://freepdfhosting.com/05dab4958c.pdf
      Silk Screen: http://freepdfhosting.com/f06c4596ec.pdf

      I have tried to mark all the components on the layout to make assembly easy. It fits into the "ABS Box - 34 x 16 x 24mm" on bitsbox.co.uk.

      Note that I have not tested the endurance of the TSAL6400 IRLEDs, but they should last well as they are intended for remote controls and matches the TSOP2438 perfectly.

  • At 2 July 2013, 1:40:40 user Ong wrote:   [reply @ Ong]
    • Hi I would like to know, because some of the component he used has already discontinued, is there an difference with

      2N2907 with 2N2907A
      CD4017BE with the one he's using

      Thank you.

  • At 27 June 2013, 13:30:49 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Sir N Most (if not all) ebay LEDs are plain crap. Rubbish. I can tell because i ran some tests for a project that had to be reliable and cheap. The test was simple: I had 4 LEDs at 5,10,20 and 25mA for 2 weeks. I will re-run this project and post the results in the site BLOG. In short, the overpowered 25mA LED died within a day (that is normal), the 20mA LED died within a few days, and the other underpowered LEDs turned dimmer day by day (compared to new LEDs that i had).
      In other words, you pay for peanuts, you get monkeys...

  • At 22 June 2013, 3:18:42 user Sir N wrote:   [reply @ Sir N]
    • Hi,

      Don't blame it on the eBay suppliers that IR-LEDs with a wavelength of ~830..850nm is not working aces with a receiver that needs a peak wavelength of around 950nm!
      The former is used for eg. night vision cams (among others), while the latter is used for remote control. Just get an LED with a wavelength matchibg your receiver (should be in the datasheet) and you're green, whether you get it from eBay or elsewhere.

      Tell me if you want some design/evaluation help with both your IR-gates :)

  • At 21 June 2013, 6:42:17 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Gerhard Smith Perfect! Thank you!

  • At 18 June 2013, 17:15:44 user Gerhard Smith wrote:   [reply @ Gerhard Smith]
    • I found something interesting on the timings for the 38KHz pulses. At 31ms/3ms, it is possble to avoid detection if you run past the beam. By changing the transmitter to transmit the 38KHz pulses at 10ms/1ms, which is still within the specs of the TSOP2438(it might not be for some of the other TSOPs), I avoided this problem. This requires the 47K to be replaced by a 15K and the 2k2 replaced by a 1K5. I did not calculate the values for the receiver as I don't use it, I use a 12F675 microcontroller, so I just adjusted the values in the code.
      I thought it might be of interest to some.

  • At 15 June 2013, 6:30:38 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @JunTung There is no opamp in this circuit. Only one relay. Connect the 5v to the relay, then the negative of the buzzer through one open contact of the relay to the ground.

  • At 13 June 2013, 12:14:49 user Gerhard Smith wrote:   [reply @ Gerhard Smith]
    • In the UK the 2N2907 is expensive( > £1 at Farnell). A cheaper alternative is the BC557 at 12pence from bitsbox.co.uk. They also sell the TSOP2438(instead of TSOP1838) and TSAL6400(IRLED) and resistors and caps cheap). The only part I could not source from bitsbox was the decade counter(4017), so I left off the NE555 and 4017 on the receiver and used a PIC12F675 instead and programmed it. That negated the best part of the receiver circuit, but made for an interesting little project. I have a PCB layout for the transmitter, but dont know how to upload it. It is done with ExpressPCB

  • At 11 June 2013, 17:08:48 user JunTung wrote:   [reply @ JunTung]
    • @Giorgos Lazaridis
      Sir, if relay can replace the op-amp, can you show me how to connect the relay together with the buzzer ? schematic K symbol means the relay right?Thanks and much appreciated :)

  • At 11 June 2013, 8:40:10 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @JunTung Sure you can. The relay can hold a lot of current

  • At 11 June 2013, 7:20:05 user JunTung wrote:   [reply @ JunTung]
    • @Giorgos Lazaridis
      Sir,is this possible to replace the led to buzzer? i mean when the beam is cut then the buzz will produce sound?according to the output voltage.Let said if it is too low,can i use a op-amp to make d voltage higher?or any suggestion sir?

  • At 11 June 2013, 7:11:55 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @JunTung Ohhh you mean the IC2P supply at top-left. Ok i got it. This is the power supply pins for the 4013.

  • At 11 June 2013, 7:01:33 user JunTung wrote:   [reply @ JunTung]
    • @Giorgos Lazaridis
      according to your receiver schematic circuit diagram. Sir.

  • At 11 June 2013, 6:59:39 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @JunTung IC2 is the 4017. What do yo umean "IC2P"?

  • At 11 June 2013, 6:53:49 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @JunTung Normlly 1.3V is the voltage across the IR LED

  • At 11 June 2013, 6:48:56 user JunTung wrote:   [reply @ JunTung]
    • @Giorgos Lazaridis

      as sir mention, IC2P is the 4017 counter?

  • At 11 June 2013, 6:22:34 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @JunTung C1 is the supply voltage smoothing capacitor. IC2 counts the pulses from the 555 timer. The IR pulses reset this chip. If the IR beam is cut, there is no reset signal and therefore the IC2 counts up to 10 which enables the output.

  • At 6 June 2013, 11:06:29 user JunTung wrote:   [reply @ JunTung]
    • Hi sir, i follow all your stated component except for IR LED n receiver. In transmitter part my IR LED cannot work becoz i get a very low voltage using DMM to check it. Is the IR LED problem? normally how much voltage cause the IR LED light up?

  • At 5 June 2013, 14:25:57 user Gerhard Smith wrote:   [reply @ Gerhard Smith]
    • Sorry I missed this in my previous posts:
      This is a great and clever circuit that is quite low-cost and easy to make.
      I especially like the receiver part as it is innovative use of simple components without the need for programming a micro-controller.

  • At 5 June 2013, 13:49:23 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Gerhard Smith No you are not missing something, this is correct. I used this at 10 meters and works with as low as 20mA - I do not have any reference of this LED (max current, peak current, frequency etc), and since it works at 10 meters, its fine for me. To drive more current, you need an extra transistor (as you mentioned)

  • At 5 June 2013, 11:20:05 user Gerhard Smith wrote:   [reply @ Gerhard Smith]
    • @Ammar:
      The TSOP1156 requires a 56KHz carrier so you can try the following values on the transmitter(no change to receiver except the TSOP):
      C1 = 0.0001uF
      R3 = 18K
      R4 = 120K
      Look here for the NE555 frequency calculator:
      Hope it helps
      Note in a funny way this might be better as it will interfere less with the 'normal' remote controls at 38KHz.

  • At 5 June 2013, 9:19:42 user Gerhard Smith wrote:   [reply @ Gerhard Smith]
    • Am I missing something here:
      If the transmitter supply is 5V then the current through the IRLED will be limited to 22ma(5V over 220R ignoring the IRLED resistance) - this hardly turns the IRLED on(100mW max). The reason for the 38KHz and bursts used in IR transmissions is to turn the IRLED on hard (200ma=max for TSAL6200 IRLED) for short bursts, allowing it to cool in between during the off period for the 38KHz and the bursts. This way much longer ranges can be achieved.
      However, the 38KHz 555 pin3 cannot supply 200ma, so the circuit would need another transistor, with emitter connector 5V supply, (similar to tranny on second 555) to provide the current to Q1.
      By reducing R5 from 220R to 33R and adding the transistor, the current through the IRLED would go to 150ma and the wattage to 750mW, which should give a much longer range.

  • At 3 June 2013, 16:42:32 user JunTung wrote:   [reply @ JunTung]
    • hi sir,just want to ask you about the circuit diagram. What is the function of C1 and IC2p there? and also the receiver ic, is it the Vs is the Vcc for this ic and Vo is the received signal output? This is nice circuit. Thanks and much appreciated sir! :)

  • At 15 April 2013, 20:27:52 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Ammar I'm sorry i cannot suggest changes to the circuit.

  • At 14 April 2013, 2:50:54 user Ammar wrote:   [reply @ Ammar]
    • what if TSOP1828 isn't available i tried to get it from all my sources.
      at end i just got tsop1156 what i have to change in circuit accordingly to use tsop1156

  • At 13 April 2013, 9:44:29 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Akhona Mafanya Anything that can block light will block the reception as well...

  • At 10 April 2013, 12:20:00 user Akhona Mafanya wrote:   [reply @ Akhona Mafanya]
    • I need to know sir, does transimitted and recieved circuits can detect the obstacles on this path??

  • At 8 April 2013, 6:12:55 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Keshav Bansal I can't remember why i decided these times. Its too long ago. sorry.

  • At 3 April 2013, 16:14:17 user Keshav wrote:   [reply @ Keshav]
    • plz explain how u decided the burst length equal to 30ms and silence to be 1.5ms while designing this circuit.....What effect can this burst length has on the range and proper detection of IR rays.....plz explain...

  • At 3 April 2013, 15:42:56 user Keshav Bansal wrote:   [reply @ Keshav Bansal]
    • can u please explain the calculations of resistances and capacitances as mentioned regarding the 'On' time and 'Off' time of the timer for both the cases i.e. 32hz and 38khz....

  • At 25 March 2013, 15:27:34 user marwan wrote:   [reply @ marwan]
    • Yeah, but i used ksm80 sensor which is similar to Tsop and used 38k hz in the transmitter but i got no progress :(
      So i thought the difference in that i send continuous oscillations and you send pulses..

  • At 23 March 2013, 21:20:59 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Marwan its the TSOP1838

  • At 23 March 2013, 14:48:04 user Marwan wrote:   [reply @ Marwan]
    • Very good, I was trying to make IR transmitter - receiver circuit but I am facing the problem of short range, until I found this topic,

      My question is, what increased the distance to be 10m instead of 2meters in the previous project??

      is it the 31hz oscillator??

  • At 7 March 2013, 20:56:03 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @samar mohammed It is not critical to be 100% 38KHz. A small error will not be a problem.

  • At 6 March 2013, 9:17:07 user samar mohammed wrote:   [reply @ samar mohammed]
    • @samar mohammed @samar mohammed @samar mohammed
      reviver circuit doesn't work we don't know what is the problem we test transmit circuit we don't get exactly 38 khz so we use choose variable resistor instead of this R4 & R5 to get the specific hz finally we get it our problem was with receiver circuit no changes happen to it even the circuit with 1cm distance could u just explain 4 us the main idea for it
      and we want to know how can i know that transmitter circuit will work for 10m
      thanx a lot ^_^

  • At 25 January 2013, 20:06:08 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @mahmoud I'm not sure about that

  • At 21 January 2013, 10:54:53 user mahmoud wrote:   [reply @ mahmoud]
    • @Giorgos Lazaridis
      I have small question can I use this circuit as beam breaker sensor with ksm803 instead of tsop1838 or 1738

  • At 20 January 2013, 10:22:05 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @samar mohammed I could only find a datasheet in chinese for this. From the drawings i think that this part should well fit.

  • At 19 January 2013, 17:32:42 user samar mohammed wrote:   [reply @ samar mohammed]
    • hello sir
      i try to do this circuit but it doesn't work... cause i don't find 1838 sensor in my country i use 0038 instead of it is that OK or will damage work ??
      thanx ^_^

  • At 20 December 2012, 5:45:24 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Jose Guilherme Tavares Monteiro that will be hard, you should rather try to avoid each circuit interfere with the other - keep the beams narrow

  • At 17 December 2012, 16:23:33 user Jose Guilherme Tavares Monteiro wrote:   [reply @ Jose Guilherme Tavares Monteiro]
    • Hi, first of all, congratulations for the excellent work in this circuit. I want to use it to count the number of people inside a particular room. My idea is to use two transmitters and two receivers, side by side, far from it other aprox. 10cm. So ,depending on which one is interrupted first I can tell if there is a person coming in or out. Can use each circuit in a different frequency so one don't interfere in the other one signal?

  • At 3 November 2012, 5:15:45 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Eney 90MHZ!!! I am not sure if it is possible with this circuit

  • At 2 November 2012, 8:36:27 user Eney wrote:   [reply @ Eney]
    • how about if i need transmit and receive the data in 90MHz in range of 20 meter..

  • At 31 October 2012, 7:30:13 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @sandeep replace the ourput relay with a 2K2 resistor. You get your output between this resistor and the transistor.

  • At 30 October 2012, 13:23:51 user sandeep wrote:   [reply @ sandeep]
    • hi friends...i am using this circuit for vehicle type and speed detection.....can anybody tell me how to connect the output of receiver to microcontroller 8051....thanks in advance

  • At 28 October 2012, 9:10:00 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Anibal Actually you do not need any change. Just use the other contact of the relay;)
      If you badly want to change the operation, then you will have to add an inverting transistor between the 4017 and the T2 driver.

  • At 25 October 2012, 1:34:01 user Anibal wrote:   [reply @ Anibal]
    • Hello,

      A single question: Which changes I need to do in the receiver to detect when the IR beam is achieving the sensor instead when it is broked.


      Anibal (Brazil)

  • At 11 October 2012, 5:47:45 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @jason of course you can eliminate both chips if you use one microcontroller. I've never used microC

  • At 10 October 2012, 1:56:18 user jason wrote:   [reply @ jason]
    • i.m planning to use this on my car parking counter using pic16f877a,do you think i can ignore the ne555d and the 4017 on the receiver section and connect the output of the tsop1838 on the microcontroller? do you know how can i programmed it usiing mikroC?

  • At 10 August 2012, 8:16:36 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Islam Qabel click to see page 2 - then click n the schematic to see it full size

  • At 9 August 2012, 23:54:31 user Islam Qabel wrote:   [reply @ Islam Qabel]
    • Plz show me the connections to CD4017CN cmos counter and what about the specific frequency from 555 to the clk input to counter...plz provide me with the connection diagram


  • At 8 August 2012, 6:20:46 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Islamqabel here is the forum

  • At 8 August 2012, 0:17:32 user Islamqabel wrote:   [reply @ Islamqabel]
    • where the board of "Your Projects" to publish the design???

      I want to send the schematic two video clips ..
      plz send me the link

  • At 7 August 2012, 19:33:02 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Islam Qabel you can post it into the forum under the boad "your projects"

  • At 6 August 2012, 22:59:25 user Islam Qabel wrote:   [reply @ Islam Qabel]
    • Hi Everybody:

      I just make a circuit for IR cut-beam circuit consist of AX-1838 IR receiver module plus the designed circuit for IR short distance cut-beam ...Please i want to publish the design for all people and send it you specially for the person who design the above circuit.
      I have a clip that shows the circuit operation plus the circuit design.

      Who want to see the design...send email to me


  • At 2 August 2012, 6:20:24 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @manac5800 probably yes. but the LEDs must be precisely the same to connect them in parallel

  • At 1 August 2012, 15:39:46 user manac5800 wrote:   [reply @ manac5800]
    • @Giorgos Lazaridis
      another question: does%uFEFF the transmitter work if i connect e.g. 20 IR LEDs parallel to the one on the output, i.e., would all 20 LEDs transmit modulated 38kHz signal as powerful as this one?

  • At 1 August 2012, 6:05:13 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Islam Qabel i do not understand the question really. Please sign up to the forum and upload the schematic. The conversation in the forum will be easier.

  • At 28 July 2012, 16:10:10 user Islam Qabel wrote:   [reply @ Islam Qabel]
    • Dear Sir:

      Thanks a lot for your reply. But i think you are not recognizing my design well. If you want to send the schematic ok. I am using AX-1838 IR receiver module and sending 1 Khz and 38 KHZ carrier frequency. I intended to use micro-controller to decide IR cut-beam or no IR cut-beam. Micro-controller receives the output directly from receiver module ....the output is 1 KHZ . The micro-controller decide beam-cut or not as following:

      Mico-controller counts the input pulses from the output of IR module (It should be 1000 or 1KHz). when No-beam cut , the counter is around 1000 pulses .. decide no beam cut .when beam-cut, counter is zero decide beam-cut. The disadvantage in this method that it take small delay when deciding.

      Could you please has any suggestions ???

  • At 24 July 2012, 20:22:54 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @manac it is not exactly a gap, it is the pulses of the signal. I do not recommend you use something unmodulated since there are many sorts of IR sources that will cause parasites to the system, like the sun and most lamps.

  • At 24 July 2012, 19:42:10 user manac wrote:   [reply @ manac]
    • @Giorgos Lazaridis As I have understood from TSOP1738's datasheet it also requires a small gap.. Could you recomend me a detector that doesn't require that? I only need a range of 2 meters max, as I plan to put it on a stairway (on each stair)...

  • At 24 July 2012, 19:26:58 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @manac The difference between TSOP1738 and TSOP1838 is that the TSOP1838 requires a small transmission gap between data sent, approximately 20mSec. If you continuously send a signal to the TSOP1838, it will eventually reject it. It is more suitable for remote-control applications rather than IR beam cut sensors. That is why i have the signal gaps in the transmission.
      Check page 3 of the datasheet that i provide for the TSOP1838 (Suitable Data Format).
      So, for this application, you can replace the TSOP18xx series with a TSOP17xx series

  • At 23 July 2012, 19:55:13 user manac wrote:   [reply @ manac]
    • @Giorgos Lazaridis thank you... another question: does the TSOP 1838 produce a continuos signal on its output or the output signal is at 32Hz? And is ti replaceable with TSOP 1738, is there any difference between these two parts except for the output logic state (TSOP 1738 produces LOW state when 38 kHz is provided)?

  • At 23 July 2012, 19:33:33 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @manac sure it is, but i cannot help with AVR

  • At 23 July 2012, 17:56:26 user manac wrote:   [reply @ manac]
    • Is it possible to replace all of the reciever parts (except TSOP1838) with an AVR microcontroller (ATMega32)? If it is, how?

  • At 10 July 2012, 9:15:54 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @varun yes you can control AC signal with the relay

  • At 10 July 2012, 7:36:47 user varun wrote:   [reply @ varun]
    • oh yes, with 4017 only one signal is transmitted and we can control till next trigger, so i think yes , am I wrong ?

  • At 10 July 2012, 7:31:05 user varun wrote:   [reply @ varun]
    • with this circuit, can i switch on an AC bulb with relay and keep it on with the help of a relay ?

  • At 30 June 2012, 5:01:02 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Himanshu the detector output is either relay or a cmos, so it is 0 when it is off.

  • At 29 June 2012, 1:50:54 user Himanshu wrote:   [reply @ Himanshu]
    • Hello Giorgos

      Could you please tell me what are the voltage at detector before and after blocking IR beam.

      my requirement is voltage should drop almost 0 when beam cut. is it possible to achieve it ? can you please help me.

      Many thanks.

  • At 2 June 2012, 8:13:27 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Darrel This is what it should do. The remote control sends pulses with very longer intervals, something that the receiver does not accept as a serial signal, therefore it appears to give pulses.

  • At 31 May 2012, 20:32:29 user Darrel wrote:   [reply @ Darrel]
    • @Giorgos Lazaridis ok so the closest thing I had was 3 100ohm resistor in parallel to give me 33ohms. now the odd thing is when ever i break the beam the reciever picks it up but when i use the remote i get pulses as i hold the button. Isnt the transmitter supposed to do the same or is it now working properly? Just so you know im using leds on the reciever npn transistors(T1) to pick up the pulses.

  • At 31 May 2012, 20:05:53 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Darrel It is not a "bad IR", it is just not correctly rated to fit my circuit. You need to calculate the R5 for your LED. So, you power the circuit with 5 volts, and you want to provide 1.3 volts to your LED at which it draws 100mA. This means that you need the resistor to drop 5-1.3=3.7 volts at 100mA

      R5 = U/I = 3.7 / 0.1 = 37 Ohms

      The resistor that i use is probably too big for you. You can also connect 2 LEDs in series and achieve 1.3*2 = 2.6 volts, and then only 5-2.6=2.4V must be dropped on R5:

      R5 = U/I = 2.4/0.1 = 24 Ohms

      Similarly, for 3 LEDs in series, 5-3x1.3 = 1.1;
      R5 = 1.1/0.1 = 11 Ohms

      Choose which setup you like and use the best resistor.

  • At 31 May 2012, 19:57:20 user Darrel wrote:   [reply @ Darrel]
    • @Giorgos Lazaridis the IR I used has a forward voltage of ~1.28V and rated at 100mA. Im fairly new to electronics so can you tell me why this might be a bad IR to use and possably a way to make it work?

      Thank you so much for your help in advance.

  • At 31 May 2012, 19:46:28 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Darrel do not expect to see any sort of blinking, it is too fast for the eye to see. Probably your IR LED is dead (since the normal LED lights). Make sure that the IR rating is correct (voltage/current) because i do not use high current IR transmitters which operate at a voltage nearly the same as normal LEDs. If you use IR LEDs with forward voltage 1.3 volts, it will have a very short and miserable life on the board

  • At 31 May 2012, 19:10:27 user Darrel wrote:   [reply @ Darrel]
    • My reciever works which I tested with a remote, but my Transmitter isnt powering the IR which is shown by my reciever not being able to pick it up. I did the phone camera already and the IR light did not show up on either the remote or my circuit. Also when I replaced the IR with an led the led worked but it wasnt blinking so I dont even think the circuit is oscilating. So what should I check?

  • At 31 May 2012, 17:35:25 user Tanay wrote:   [reply @ Tanay]
    • @Persia: I very simple test to check an IR LED, use mobile phone's camera. It will show a white light coming out of the LED when powered.

  • At 31 May 2012, 15:13:26 user Darrel wrote:   [reply @ Darrel]
    • Hello I recently built the transmitter and receiver and im having a problem with current to my IR. the receiver works well I was able to test it with a remote but my transmitter Isnt powering the led. im using a 5v usb supply and I believe the circuit is wired right. I dont have an osiliscope but I have been taking measurement with a multimeter.
      also i switched this IR and its resistor out for a red led and a resistor and it lights up. Do you know why the IR doesnt light up or getting the current it needs?

  • At 27 May 2012, 10:38:32 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Tanay yes, increase this frequency on both rceiver/transmitter

  • At 27 May 2012, 7:31:17 user Tanay wrote:   [reply @ Tanay]
    • How can I lower it down to about 6 ms?

      Can I get the desired results by increasing the frequency of second 555 timer (the one with 32 Hz freq.)?

  • At 27 May 2012, 5:26:42 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Tanay At maximum 555 frequency, the obstacle has to remain for one full IR pulse plus 1/9 of it. That is 31 mSec 3.4 = about 35 mSec. After 35 mSec, the load will be activated.

  • At 25 May 2012, 17:26:53 user Tanay wrote:   [reply @ Tanay]
    • What would be the maximum number of obstacles successfully sensed by this circuit in 1 sec?

  • At 12 May 2012, 22:04:22 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Kamel Thanks Kamel, you are really awesome!

  • At 12 May 2012, 16:35:53 user Kamel wrote:   [reply @ Kamel]
    • I bought a bunch of IRs and did some testing, following IRs will work with 10 meters range.

      L-7113SF4BT (Kingbright)
      L-7113F3BT (Kingbright)
      TSAL6100 (VISHAY)
      IR333A (EVERLIGHT)

  • At 7 May 2012, 4:56:41 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Saiful Hello. It is definitely the LED the problem. You need to get a better LED.

  • At 6 May 2012, 23:45:28 user Saiful wrote:   [reply @ Saiful]
    • Good day sir.
      My name is Saiful, from malaysia.
      My email is nnytime_2cu@yahoo.com.
      tq so much for giving me the chance to use your circuits :)

      I have questions regarding to your Long range IR beam break detector circuit.
      I'm using your circuit as my project for my Final year project.
      I have a little problem with the transmitter.
      I'm using a regular IR LED.
      When it transmit, the receiver starts to blinking.
      But when i used a tv remote control, it was working well, i mean OFF lights completely when i press any buttons from my tv remote control.
      What was the problem sir?
      Do i need to change the IR LED transmitter into something better sir?

      another question about the receiver.
      how can i invert the indicator which means, when i transmit, it goes ON.
      any alternative, sir?
      Looking forward for your answer.

  • At 17 April 2012, 22:57:44 user Felix Khan wrote:   [reply @ Felix Khan]
    • Many of the people who have tried making this circuit would have found it fall short of 10 meter distance.

      I do have a circuit I designed back in 1992 that using a Power Supply PWM. It works great with old Radio Shack GP1U52X IR receiver. It allows you to adjust the sensitivity to sense even a very thin wire. The IR LED I used were SHF485 designed for 200mw and a surge current of 2.5A. It is a rugged and designed for high power IR applications.

      If any of you are interested in my IR break beam circuit then please send me an e-mail and I will be happy to send you an updated version of my circuit.

      My IR transmitter and receiver is designed to fire a camera or a photoflash. However, with a little modification one can use it for all sorts of application.

      This IR transmitter can be use with just about any receiver since you are able to adjust both the Pulse Width and the Modulation Frequency.

      Best regards.

      Felix Khan

  • At 12 April 2012, 6:26:00 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @ERWIN I'm happy that this works for you. As for the donation, i have a donation button in the home page, but i really prefer receiving things instead, like books (used or new), tools (again used or new), broken devices, old motors, lcds, unused chips, you know, things that can be used for the site and can be easily shipped. Money have no "memory", so if i add a book to my bookcase which i received from a person from a far country, that would be amazing.

  • At 11 April 2012, 21:54:40 user ERWIN wrote:   [reply @ ERWIN]
    • i;ve got the reciever on page 2 , thanks !How about a donation on this site, do you accept it?for the benefit also of those newbies and electronics enthusiasts and to keep it running,,,,what can you say gentlemen?

  • At 11 April 2012, 21:46:34 user ERWIN wrote:   [reply @ ERWIN]
    • Question again, are we gonna utilize the reciever circuit of short distance project ?what reciever are we gonna use on this one?thanks!

  • At 11 April 2012, 14:14:11 user ERWIN wrote:   [reply @ ERWIN]
    • Thanks for publishing your circuit online , I will build this circuit
      since one of my belonging was stolen inside my property, so plan to install this in the perimeter of my property and planning to install
      cameras now.Thanks again and more power.

  • At 14 March 2012, 15:18:09 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @ADEL here is how to do it. The emitter of T2 must be connected directly to ground (remove the relay completely). Then add a resistor at the collector of the T2: One side of the resistor goes to 5V, the other goes to the collector of T2. The microcontroller will then be connected at the point where the resistor connects to the T2 collector. The resistor should be something like 2200 Ohms or similar.

  • At 14 March 2012, 14:31:06 user ADEL wrote:   [reply @ ADEL]
    • thanks for your efforts
      can i connect the ouput of reciever circuit after the R7 to the input of micro controller to count the number of blocking and if it need any additional commpenets i hope you give me your experince

  • At 6 March 2012, 13:44:20 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Kevin the point is that the tsop has an internal transistor which reverses the signal. what you say is correct, but the difference is that the tsop has high voltage in standby and sinks when ir is received.

  • At 5 March 2012, 23:11:01 user Kevin wrote:   [reply @ Kevin]
    • Hello, and thank you for this helpful article! I am an electronics amateur, so I apologize if this is a basic question. I am trying to build a beam break circuit to trigger events in a behavioral neuroscience experiment. Before building I tried to simulate the circuit to see if it behaves the way I want, but got strange results.

      It seems to me that the voltage at the reset pin of the counter is low during positive pulses from the TSOP module, and high during the spaces between positive pulses. This results in the alarm being triggered only when the IR beam is detected as being 'on' for too long of a time. I found that replacing T1 with a PNP transistor allowed for the appropriate behavior. It seems that in your design, the pulses shunt the current going to the reset counter to ground, allowing for the counter to advance to 9. Am I correct in thinking this, or am I missing something?

      Thanks again for all of your help!

  • At 29 February 2012, 22:43:15 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @ADEL a pull-up resistor is connected between the positive supply and the pin you want to "pull up"

  • At 29 February 2012, 6:44:43 user ADEL wrote:   [reply @ ADEL]

  • At 22 February 2012, 6:49:12 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @specticals hello! first, this is not laser, it is infra red. As for your question, in a single word: yes, you can connect it. But you may face problems with bouncing so some kind of one-shot circuitry would be good to have in between.

  • At 21 February 2012, 13:07:13 user specticals wrote:   [reply @ specticals]
    • @Giorgos Lazaridis thanks for the help!

      I am just wondering if it would be possible to have 2 of these circuits, 1 connected to the up input of a (74LS193) and the 2nd connected to the down input so that when the laser has been crossed at the up input it will count up one on the 7 segment display and then down 1 if the 2nd beam is crossed.

      Any help with this would be appreciated.

      kind regards,


  • At 19 February 2012, 9:54:18 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Specticals you can do this. remove everything after R7 of the receiver, and connect the R7 to the clock input of a BCD counter (eg: CD4518). Then use a BCD to 7-seg decoder (eg cd4511) to drive your 7-segment

  • At 16 February 2012, 23:25:29 user Specticals wrote:   [reply @ Specticals]
    • Hello,
      can anyone tell me if you are able to connect a 14 segment display onto this and have it count up/down from 10.
      what components and modification may be needed?

      kind regerds,


  • At 7 February 2012, 7:14:36 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Ravi you cannot measure it with volt-meter because of the frequency. You can only put an oscilloscope to test. As for the voltage, this is not standard. If you scavaged an LED from remote control, then you probably need about 1 volt across the LED. Any more than this may harm it. Usually, IR LEDs have 1.2 forward voltage, but i used one with 3 (different LED).
      You can make a test to see the maximum voltage across the LED. Connect R5 to the positive and R6 to the negative supply. This will light up the LED at full brightness. Then you can measure the voltage drop across it with volt-meter. But if you have done something wrong with R5, the LED will burn instantly. I suggest that you start with a bigger R5 value and do this test until you get the desired voltage.

  • At 6 February 2012, 19:28:38 user Ravi wrote:   [reply @ Ravi]
    • @Giorgos Lazaridis
      sir what is the required value of voltage across the ir transmitter ?
      i got just 0.13v

  • At 5 February 2012, 23:19:37 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Ravi i am not sure for the differences between the tsop17xx and 18xx, but from a quick look i saw that 18xx has more "tight" filters. Normally, the 17xx should work. Make sure that the transmitter works correctly. An oscilloscope would help. Unfortunately i cannot do much without more data.

  • At 5 February 2012, 19:08:59 user Ravi wrote:   [reply @ Ravi]
    • @Giorgos Lazaridis
      thank you very much for that
      i have done everything whatever is shown, but i have tsop1738.
      so can you please tell me what are the changes i should have.
      i have use ir led of a TV remote,and its working but receiver circuit is not work..

  • At 3 February 2012, 20:36:19 user Giorgos Lazaridis wrote:   [reply @ Giorgos Lazaridis]
    • @Ravi No problem at all. i use also common ground

  • At 1 February 2012, 19:18:04 user Ravi wrote:   [reply @ Ravi]
    • hello
      please anybody tell me that is there any problem regarding to common ground ? I've used only 1 source of a power supply for both transmitter and receiver.

  • At 18 January 2012, 19:00:07 user Daniel wrote:   [reply @ Daniel]
    • its just that am doing a project and this circuit has almost everything i need for it but for my circuit i need an output pf 1 pulse per millisecond. but thanks anyway

  • At 18 January 2012, 18:13:49 user Kammenos wrote:   [reply @ Kammenos]
    • @Daniel i really do not remember the formula for calculation and this is an old project. But why change the time?

  • At 18 January 2012, 15:03:21 user Daniel wrote:   [reply @ Daniel]
    • on the transmitter circuit, what value for C3 and R2, do you think i need to in order to archieve an output of 1 millisecond resolution. thats to generate 1 pulse every millisecond.

      kind regards

  • At 15 January 2012, 9:43:14 user Kammenos wrote:   [reply @ Kammenos]
    • @Patel yes it will, i made this circuit for microcontroller interface. Remove T2 and K1, reduce R7 to 1KOhm and connect it to your microcontroller. You may need to add a pull-down resistor like 10K.

  • At 12 January 2012, 8:44:51 user Patel wrote:   [reply @ Patel]
    • Sir,I want to connect microcontroller ... it will work properly??

  • At 6 January 2012, 19:29:22 user Kammenos wrote:   [reply @ Kammenos]
    • @j.j.sathian here is a link with excellent high-power LEDs:

  • At 4 January 2012, 19:21:35 user j.j.sathian wrote:   [reply @ j.j.sathian]
    • sir,i want to know the number of high power led and which make i have to
      use.kindly furnish the number of led,because i do not take from tv remote.

  • At 30 November 2011, 21:22:04 user sam wrote:   [reply @ sam]
    • I registered, but I'm not able to log-in because I haven't received the conformation email.

      For the timer, I meant LM556N. looking at the schematic, I'm wondering if I need to invert the rest pin.

  • At 30 November 2011, 21:16:13 user Kammenos wrote:   [reply @ Kammenos]
    • @sam what kind of problems do you have in the forum? And what timer ship???

  • At 30 November 2011, 21:07:20 user sam wrote:   [reply @ sam]
    • I'm having difficulty logging it into forum.
      I'll post a close image as soon as I could log in...
      I'm also wondering about the rest pin in the timer ship. Is it inverted?

  • At 30 November 2011, 20:39:55 user Kammenos wrote:   [reply @ Kammenos]
    • @sam sorry, i cannot help you without knowing what you've done. You may wanna post some close images in the forum...

  • At 30 November 2011, 19:57:48 user sam wrote:   [reply @ sam]
    • I built the exact transmitter circuit, I keep getting 40KHz from both timers. I'm not sure what is wrong... Please help.

  • At 30 November 2011, 16:01:46 user Kammenos wrote:   [reply @ Kammenos]
    • @servesh with what do you measure the voltage and the frequency? are these peak to peak values from oscilloscope? the voltage across the led must be according to the manufacturer. Usually, IR leds may have about 1.2 volts (to work on remote controls)

  • At 30 November 2011, 8:30:46 user servesh wrote:   [reply @ servesh]
    • hello sir;
      sir i hv made this ckt .and i hv used led in the out put of receiver ckt as indicator . this ckt is good when d distance b/w tran. and rec is abut 1.5 meter and led is high (glowing), but when i increase above 2 meter led on receiver ckt start blinking
      After giving a lot of time i found following results-
      1- The receiver circuit working well with TV Remote up to 10meter.
      2- In transmitter circuit the voltage across Ir led is 0.070 volt.
      frequency at pin 5-29Hz (which is 32 Hz in yr ckt)
      frequency at pin 9-3.8Khz(which is 38 kHz in yr ckt)
      3- When i replace R6 by 470 ohms n R5 by 100 ohms voltage across ir led is 0.090volt.
      plz help me

  • At 5 October 2011, 18:21:40 user Kammenos wrote:   [reply @ Kammenos]
    • @servesh i suppose that the problem is the LED. Are you sure it operates well? Do you have the proper voltage across it?

  • At 5 October 2011, 7:14:36 user servesh wrote:   [reply @ servesh]
    • sir ,
      from formula f= 1/T = 1.45/(Ra+2Rb)C.(for Astable Configuration)
      putting value according yr figure,
      it gives frequency=41.95kHz.

  • At 5 October 2011, 6:43:34 user servesh wrote:   [reply @ servesh]
    • plz help;
      sir i hv made this ckt .and i hv used led in the out put of receiver ckt as indicator . this ckt is good when d distance b/w tran. and rec is abut 1.5 meter and led is high (glowing), but when i increase above 2 meter led on receiver ckt start blinking.
      it mean my ckt worked for only 1.5 meter. in transmitter ckt i hv used TV remote ir led.
      sir wt u made(circuit) with TV IR led work upto 10 meter ?
      plz help me sir.my project is in dilemma.

  • At 24 September 2011, 17:42:46 user Kammenos wrote:   [reply @ Kammenos]
    • @rey you can search in ebay.

  • At 24 September 2011, 10:29:12 user rey wrote:   [reply @ rey]
    • where Can I Buy this parts?
      TSOP1838 38 KHz Photo Modules for PCM Remote Control Systems

  • At 24 September 2011, 10:23:02 user rey wrote:   [reply @ rey]


      TSOP1838 38 KHz Photo Modules for PCM Remote Control Systems

  • At 21 July 2011, 14:44:24 user Kammenos wrote:   [reply @ Kammenos]
    • @servesh from what i have de-cipher from your message, i suppose that you must use a better LED. Check out Alan's store here:

  • At 21 July 2011, 11:05:29 user servesh wrote:   [reply @ servesh]
    • hello sir,
      i hv tried this ckt but unable to get suficient result.
      i hv complited yr short distance ir trans/rece, it is working fine.
      but i m getting problem in long range.i hv tried this ckt wd proper component,but it is not wrking. i hv used ir led which was used in short range, is should work. or replace it TV remote LED.
      if i take the rec(long range) ckt towards short range transmitter will it detect. in the same way long range tranmitter->short range receiver .

      plz help me...

  • At 8 July 2011, 4:26:32 user servesh wrote:   [reply @ servesh]
    • thankyou sir

  • At 6 July 2011, 10:58:25 user Kammenos wrote:   [reply @ Kammenos]
    • @servesh 1.depends on the LED. different LED emits different wavelength.
      2. you can use whichever frequency you like, as long as you tune the receiver to this
      3. i did not have in stock.

  • At 6 July 2011, 7:10:04 user servesh wrote:   [reply @ servesh]
    • hello sir;
      sir i have some question-
      1- which type of rays emits IR LED's near,mid or far infra red rays.
      2- You have taken a frequency coming from IC1A 32Hz (which is a modulated frequency ) and another coming from IC1B 38KHz(which is a carrier frequency) and them modulating and inverting with transistor.
      is this is standard frequency or we can change (what should be range)?
      3-In Questn ask by PICMICRO u are saying BC547 can work for BC337
      and BC547 also work for BC548. Then why u have taken separate transistor(548,337),why u hv not taken 547 for both.

      i m waiting your response.

  • At 20 June 2011, 14:45:53 user picmicro wrote:   [reply @ picmicro]
    • O thank you sir.

  • At 17 June 2011, 19:59:45 user Kammenos wrote:   [reply @ Kammenos]
    • @picmicro 2N2907 is PNP 2N2222A is NPN so they do not match. BC337 by-> BC547 probably is ok. BC548 by-> BC547 is ok.

  • At 16 June 2011, 5:46:09 user picmicro wrote:   [reply @ picmicro]
    • hello sir,
      in large distance IR transmitter/receiver circuit can i modified component(transistors)in following manner-
      2N2907 by-> 2N2222A
      BC337 by-> BC547
      BC548 by-> BC547
      if no, give me the reason why?
      Please i need your kind help.

  • At 30 May 2011, 10:26:44 user picmicro wrote:   [reply @ picmicro]
    • Thanks a lot Kammenos,
      now i have completed my circuit . and it is working well and its range is 9.5 centimeter.i have used transparent white Led type IR transmitter & receiver.
      Now i going for large distance....Thanks A lot Kammenos.

  • At 29 May 2011, 4:46:27 user Kammenos wrote:   [reply @ Kammenos]
    • @picmicro this part is designed to work reverse-biased. there are some parts, like for example the zener diode, which are designed to be connected reverse biased in order to operate normally.

  • At 28 May 2011, 5:16:02 user picmicro wrote:   [reply @ picmicro]
    • sorry sir i m not getting your point. why it is reverse bias. what will be result if it is in forward bias as generally.
      please help me sir

  • At 27 May 2011, 11:44:43 user Kammenos wrote:   [reply @ Kammenos]
    • @picmicro because this is how IR receiver LEDs are supposed to be connected.

  • At 27 May 2011, 10:21:30 user picmicro wrote:   [reply @ picmicro]
    • i mean to say IR receiver led in reverse bias.

  • At 27 May 2011, 10:17:48 user pcbheaven wrote:   [reply @ pcbheaven]
    • thanks sir,
      it mean timer circuit generate carrier signal(of frequency of 7khz) for IR led signal.
      why u have used receiver circuit in reverse manner.

  • At 27 May 2011, 4:58:36 user Kammenos wrote:   [reply @ Kammenos]
    • @picmicro i used a timer to generate a modulated frequency, to avoid false triggering from ambient IR light (which is unmodulated)

  • At 27 May 2011, 4:55:23 user picmicro wrote:   [reply @ picmicro]
    • Hello sir thanks for this nice help,
      sir i want to know that why you have used timer in transmitting circuit . why we not used IR Led alone .Please clear my confusion.
      i want to make this circuit in my project.
      Thanks alot .

  • At 18 May 2011, 13:18:01 user Rashed wrote:   [reply @ Rashed]
    • Hi

      i tried to use the 555timer to generate a certain frequency. I keep getting different frequencys than the one i calculated.
      I'm using f= 1 /(0.67(R1+2*R2)*C)

  • At 3 May 2011, 14:15:24 user Kammenos wrote:   [reply @ Kammenos]
    • @ankit maggu it is on the second page. go to page 2

  • At 3 May 2011, 12:08:10 user ankit maggu wrote:   [reply @ ankit maggu]
    • hi Giorgos
      the circuit u shown its transmitter circuit but where is a reciever circuit????or how 2 make it????please reply.

  • At 19 April 2011, 5:39:40 user Kammenos wrote:   [reply @ Kammenos]
    • @CRIS yes indeed, but that has nothing to do with the LED voltage. Notice that i use 5 volts! With the proper resistor everything can be done.

  • At 19 April 2011, 3:02:45 user CRIS wrote:   [reply @ CRIS]

  • At 2 April 2011, 8:50:34 user Kammenos wrote:   [reply @ Kammenos]
    • @salini reduce R7 to 1K and you can directly drive the microcontroller input from R7. The transistor and the relay are not necessary.

  • At 2 April 2011, 4:04:02 user salini wrote:   [reply @ salini]
    • am doing a project on bidirectional visitor counter using micro controller.the interrupt i give is the output of ir transmitter and receiver.can i use the output of your circuit to give the interrupt to micro controller,if no could you tell me the modifications i have to do
      thank you in advance

  • At 25 March 2011, 5:11:25 user Adzlan wrote:   [reply @ Adzlan]
    • currently im using a 12V power supply 2A regulated to 5v via the lm7805. Then directly connect to the transmitter circuit. I think my transmitter circuit having problems. My receiver also is connected to the power supply but it functions without problem (tested with remote control).
      The problem is i need to frequently adjust my variable resistor. Btw, ill try to make your circuit today with 10 IR leds using 9v batery regulate to 5v.

  • At 24 March 2011, 11:16:31 user Kammenos wrote:   [reply @ Kammenos]
    • @Rashed i' m sorry, i do not do circuits on demand, and this project is not going to be very easy. You need to do some research and tests first.

  • At 24 March 2011, 9:30:13 user Rashed wrote:   [reply @ Rashed]
    • Hi Kammenos

      thanx alot for your answers and comments.

      if that doesn't bother you, could you tell me preifly how to do it using microcontroller. specilly the modulation and demdulation part. as i need it in my project. and could u guide me to where i could find the right information about it.

      your help is apreciated. your right to refuse is respected.

      thanks again

  • At 24 March 2011, 8:13:58 user Kammenos wrote:   [reply @ Kammenos]
    • @Adzlan the only problem that may occur is if the current for the 10 LEDs is too much. IR LEDs tend to draw lot of current if the voltage is increased. This is a parameter that you need to take into consideration if you plan to power the transmitter with battery. No change needed, as long as each LED has the proper resistor in series.

  • At 24 March 2011, 8:11:02 user Kammenos wrote:   [reply @ Kammenos]
    • @Rashed with microcontrollers you can modulate the signal to add as many as you want, but that is a completely different case.

  • At 24 March 2011, 2:47:09 user Rashed wrote:   [reply @ Rashed]
    • Hi Kammenos

      even if i used a microcotroller?

      thanx again

  • At 24 March 2011, 2:10:54 user Adzlan wrote:   [reply @ Adzlan]
    • hello,
      can this circuit be connected with a 10 parallel IR LEDs? Will the transmission be stable? I only need a distance of transmission not greater than 1 meter. Before this im using a single 555 timer where i connect 10 IR LEDs but the circuit was using a variable resistor of 5k. The circuit having some difficulties in maintaining a frequency of 38khz. So i decided to switch to a fix value of resistor.

  • At 23 March 2011, 21:32:10 user Kammenos wrote:   [reply @ Kammenos]
    • @Rashed no, not with this circuit

  • At 23 March 2011, 14:21:06 user Rashed wrote:   [reply @ Rashed]
    • Hi

      Is it possible to use two beam sources (of different frequency) and one detector, so when the first IR source is cut one LED will illuminate and when the other is cut another LED will illuminate? and what changes should be done?

      thanks alot

  • At 17 March 2011, 7:04:40 user Fung wrote:   [reply @ Fung]
    • Emm...after an advanced test, the actual detecting distance is about 9m (3 times of that before), even the output of the IR LED is quite low, I will leave it unchanged except the timing parts R3 and R4.

      I believe that the detecting distance can be widened after decreasing the frequency.

  • At 13 March 2011, 21:01:00 user Kammenos wrote:   [reply @ Kammenos]
    • Better you use 10uF capacitor, R1-47K and R2=100K potentiometer. You can change the potentiometer to find the 1Hz you want.
      Regarding the 555, it must be connected to the output of T2. If 555 fails to work this way, then you may need to give little bit more voltage to T2 collector and IC2, like for example 6 or 9 volts. But only on T2 and IC2. TSOP voltage must not exceed 5V. But i believe that it will work with 5V normally.

  • At 13 March 2011, 18:07:08 user steven wrote:   [reply @ steven]
    • I plan to use R1 = 3K3 and R2 = 5K6 and C1=100uF.
      that will produce 1Hz. How do you think?

      So the output of the TSOP will be connected to which pin of the 555?

  • At 13 March 2011, 17:34:02 user Kammenos wrote:   [reply @ Kammenos]
    • fung run the test that i told you with the LED to see what current draws while voltage raises. The best is to have both an ammeter and a voltmeter connected to read out values simultaneously. Then you can decide which transistor to use.

  • At 13 March 2011, 16:34:25 user Fung wrote:   [reply @ Fung]
    • After changing R6 to 470ohms, the voltage across IR LED has decreased to about 30mV even without changing R5. If R6 uses 680ohms, the voltage across IR LED has increased to about 70mV. Totally speaking, no change.

      Is that the problem comes from the frequency?

      The collector current of 2N2907 is lower than that of BC328 by 200mA difference, is it better to use transistors which have lower collector current such as BC327 (Ic=-500mA)?

  • At 13 March 2011, 15:51:08 user Kammenos wrote:   [reply @ Kammenos]
    • hmmmmmmm i strongly suggest you use 2n2907.
      You can try to increase current by increasing base current. So, reduce R6 down to half or less. 470 ohms is a good start, then 330. I think that R5 is already too low. Change to 100 ohms before any test.
      So do this: R5=100, R6=470 and measure voltage across LED and current. Note also that there are some LEDs that draw like 1 ampere in nominal voltage. Your transistor and 2n2907 cannot handle such current. So it may not be wise to go to nominal voltage of the LED. Get the LED specifications, or take a wild guess. If i were you, i would test the LED first with a potentiometer and see how the current increases regarding the voltage across it. If near 1.3 volts the current jumps to high numbers, then it is a low voltage high current IR led (very common in IR transmitters).

  • At 13 March 2011, 15:44:40 user Kammenos wrote:   [reply @ Kammenos]
    • you can connect the 555 either directly on the output transistor, or through the relay. Regarding the RC of the 555, you need to calculate it. Read the theory

  • At 13 March 2011, 15:43:45 user Fung wrote:   [reply @ Fung]
    • I will try to decrease the frequency, however the voltage across IR LED is too small, which is about 50mV, this is an extremely small value so that I have to do something to increase the voltage. Without changing the BC328 (Ic=-800mA max), what should I do?

      The original value of R5 that I have used is 33ohm. Supply voltage is 6V (actually 5.2V). Should I increase the voltage supply or decrease the value of R5?

  • At 13 March 2011, 15:24:38 user Steven wrote:   [reply @ Steven]
    • Hi Kammenos,

      The value R1,R2 and C1 of the Astable Multivibrator need to be design to produce 1 or 2 hz at the output?

      how to connect the receiver to the Astable Multivibrator?

  • At 13 March 2011, 10:22:42 user Kammenos wrote:   [reply @ Kammenos]
    • 53KHz is normally too high. As far as i know, TV remote controls are from 48 to 50KHz. If the IR LED comes from a remote control, then most probably the forward voltage is 1.5 volts and not 3.2. You need to check the voltage across the LED when connected to DC suppy, and choose the correct resistor, otherwise it will be destroyed or it will not transmit IR.

  • At 13 March 2011, 9:01:04 user Fung wrote:   [reply @ Fung]
    • Known that the IR LED in the transmitter is powerful because it comes from a remote control. However when I test it with a distance >3m, the receiver becomes unable to receive the signals. The frequency of it is 53KHz, is the frequency too high? Should I decrease the frequency?

      Also, I found an interesting thing after adding 6 LEDs to other outputs on 4017 except Q0-Q2, as the frequency increase, more LEDs blink, they become a meter of sensitivity.

  • At 12 March 2011, 20:11:18 user Kammenos wrote:   [reply @ Kammenos]
    • steven, use a 555 as an astable multivibrator to make an led blink. Or better, get a flash-led, but this has a fixed frequency hat cannot be changed (usually between 1 to 2 Hz).
      For the 555, check out my theory pages i have a page with basic 555 circuits

  • At 12 March 2011, 10:36:30 user steven wrote:   [reply @ steven]
    • Hi,

      Can someone provide the schematic of the blinking LED.
      I had tested my transmitter and receiver using a scope. They worked perfectly well, and i wish to connect the output of the receiver to a LED.
      Easier for me to check whether my hardware is in good condition. Thanks

  • At 1 March 2011, 22:03:43 user Kammenos wrote:   [reply @ Kammenos]
    • Use an oscilloscope.

  • At 1 March 2011, 11:01:24 user David wrote:   [reply @ David]
    • HI,

      I had build the circuit and successfully got the received signal.
      but i don't know how to check output stage (low or high).
      can somebody explain that.

  • At 25 February 2011, 18:24:16 user Kammenos wrote:   [reply @ Kammenos]
    • justin, i opened a thread in the forum for your question. Go there:

  • At 25 February 2011, 12:01:42 user justin wrote:   [reply @ justin]
    • Hi

      I am doing automatic room light controller with bidirectional.
      I will use 2 transmitter(TSAL6200) and 2 receiver(TSOP4838) at each side of the door.
      lets assume
      S1 is the first pair of transceiver
      S2 is the second pair.
      if S1 is obstructed before S2,mean people go in
      If S2 is obstructed before S1,mean people go out.

      MY question is will the 2 receiver wrongly received the signal from other transmitter?
      mean 1st receiver received signal from 2nd transmitter,etc

  • At 15 January 2011, 14:39:03 user Kammenos wrote:   [reply @ Kammenos]
    • Depends on the speed and the surface as well. Most probably it will work, and if not, you can increase the frequency to make it more sensitive. But that is something that needs to be tested.

  • At 14 January 2011, 23:27:44 user Jabsco wrote:   [reply @ Jabsco]
    • Hello!I am considering using this circuit as a photocell gate for a bicycle race timing system.So I was wondering if its sensitive enough to detect fast passing objects (30-50km/h)?Thanks!

  • At 28 December 2010, 18:04:13 user Fung wrote:   [reply @ Fung]
    • I got some 22pF ceramic capacitors, I am going to use one of them with R3=160K, R4=500K (1%), calculated the frequency f=56.544kHz. Is it acceptable if the frequency is above 50kHz?

      What modifications should I do for R1, R2 and C3 if I use the values above?

  • At 21 December 2010, 21:30:57 user Persia wrote:   [reply @ Persia]
    • Hello,
      if you just want to detect beam-break you don\'t need that much of the receiver. I might be missing something about your intended application but suggesting to check out a $one 5mw 780 nm IR laser like DL-3150-101
      its range well beyond 100m (design dependent)

  • At 21 December 2010, 15:27:07 user Kammenos wrote:   [reply @ Kammenos]
    • sure it is ok

  • At 20 December 2010, 17:15:54 user Fung wrote:   [reply @ Fung]
    • As you mean that, K1 and D1 are the "output" part of the receiver. I use a resistor (about 220R) and an LED in series to replace K1 and D1 at the emitter or T2, is it okay to do?

  • At 20 December 2010, 16:04:22 user Kammenos wrote:   [reply @ Kammenos]
    • Fung, you can connect whatever load you want nstead of relay, as long as it operates at 5 volts and does not draw more current as the transistor permits.
      You can connect LEDs to the outputs of the cmos.

  • At 20 December 2010, 15:43:05 user Fung wrote:   [reply @ Fung]
    • If a relay (K1) is not used, what alternative(s) should be used?

      It is quite wasting for outputs 0-8 of the 4017 remain not used, if I add a LED to each of the output except output9 for decorations, will they affect the circuit? If yes, I won't add them.

  • At 20 December 2010, 6:26:18 user Kammenos wrote:   [reply @ Kammenos]
    • 1) there should be no problem using the 1738 (i hope)
      2) No this cannot be used as a movement sensor.

  • At 19 December 2010, 23:17:01 user Panagiotis wrote:   [reply @ Panagiotis]
    • Hi george...Finally you made it!!!!!It is amazing and my congratulations again for the new project.Well i have 2 questions...
      1)If i use a tsop 1738 instead of 1838 does it matter?
      2)can we use this circuit as a movement sensor?

      --|>|-- #### --|>|--

  • At 16 December 2010, 6:20:31 user Kammenos wrote:   [reply @ Kammenos]
    • - BC328 should also work, although i have not test it.
      - The previous version has another way of decoding IR and different frequency. You cannot replace the IR Diode.
      - If you connect other pin than 9, either the output will be always armed, or the circuit will be unstable and extremely sensitive. Unless of course you decrease the 555 frequency, but if you read how it works you will see that there is absolutely no good in doing this.

  • At 15 December 2010, 14:35:01 user Fung wrote:   [reply @ Fung]
    • After reading the BOM, I raised some questions. Must I use a 2N2907 (because I found difficulties to buy it)? How about the BC32X or BC55X transistors? Are they acceptable?

      In the previous version of this circuit, the IR LED which I used was also from a remote control of a toy (the toy was no longer work...).

      In this version of the circuit, the receiver is a photo module, which look likes the IR receivers which I have (I can provide a photo of it if needed), can I apply it into the previous version? If yes, what modifications should I do on it?

      Why only the output 9 is used? If I connect other outputs, what changes may be observed? (I have no tests on this circuit)

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