Worklog - The electronic part: The Shaker guide controller (September 28 2010)
The next module that needs of a controller is the shaker liner guide. This controller is going to be very easy compared to the previous 2, because it only needs to control the direction of a DC motor. I added also a linear DC motor speed controller, to reduce the speed. The speed is controlled by a potentiometer on the PCB.
Here is the schematic diagram of the circuit (as always, click to enlarge):
I use 2 relays to control the motor. The first relay (K1) turns on and off the motor and is driven through Q2. The next relay, K2, will change the polarity of the motor, and thus it controls the direction. This relay is controlled through Q3.
The transistor Q1 is the one that controls the voltage of the motor. This is done by adjusting the potentiometer R4.
Finally, R5, R6 and the zener D1 are used for the encoder. The signal of the encoder is 12 volts. The zener will drop it down to 5 volts (for HIGH state), and the R6 is pull-down resistor, as the signal will be driven to the master microcontroller. R5 is current limiting to protect the Zener.
The Printed Circuit Board
I will not go through the whole procedure that i do to make a PCB, as i have already show this in the previous pages. So, here is the PCB complete, with all the components soldered:
The motor draws about 2.5 Amperes at 12 volts. That is 30 Watts. The transistor Q1 needs of a large heat-sink to operate, as it needs to dissipate a lot of power when working. What i really did, is to cut a 16x10mm aluminum U profile, about 30mm long, and use it as a heat sink. It is not a perfect solution, but hey, the motor will only run for a couple of seconds each time. I tested this heat-sink for about 2 minutes of continuous operation, and proved to be quite reliable. No need to mention that i could easily bake eggs on it...
Then, i began wiring the limit switches:
The tools that i used
First the bottom limit switch
And then the top limit
Both switches goes to the PCB using a polarized pins header
Here is a picture with the PCB connected for test-run:
The controller works perfect. When 5volts (hight is applied to the "start" pin, the motor goes down with the pre-selected speed. If the limit switch is actuated, the motor stops immediately, and the "Bottom Limit" output is driven low. The motor can only move upwards.
When the "direction" pin is high (5 volts), the motor moves upwards, until the top limit is actuated. The motor will then stop, and it will only be able to move downwards. Moreover, the "top limit" output will be driven low.
The encoder interface also works fine. The pulses are successfully converted form 3-12V to 0-5 volts.
@Alex In Greece during the Ancient times there was this saying: "Oyden monimoteron ek toy prosorinoy" which means that "nothing is more permanent than the temporary".
But now that you said that again, i think i should restart this project, shouldn't I? Hopefully within this year.
Hi you have a nice coffee Instant Cold Coffee Machine but you wanted to use a fridge for cold water but no water cooler that you use waron also in coffee automaaten is where you can get I know old water out of if not the name but it can look for you we have that built-in devices greetings alex
Hello George. Regarding the elements, these are hardware wiring to indicate wire connections between the modules. The orange boxes indicate wires coming from the output module (Digital Output Module - DOM), and the green indicate wires going to the Digital Input Modules. Notice that for example, from module "Rotary table", 4 wires comes out, then 2 of them arrive from the DOM and 2 goes to the CPU.
As far as the diode is concerned, this is only for polarity protection. It is the same as the D2. But you are right, It is not necessary and i may not put it after all.
I think your architecture diagram (first figure) is slightly confusing, because it seems to include elements of code (the elements above the CPU) with hardware elements. Ideally, you would have a system-level block diagram detailing your hardware and a separate functional block diagram to describe your code. If I'm misreading your architecture diagram, feel free to ignore this.
Secondly, looking at your reset circuitry, I see you have a 1N4148 diode between your microcontroller pin and your ICSP header (pin 1). I'm fairly certain this diode is not necessary, so you may want to double check that.
Frappé has become very popular here in the States. The difference is we use fresh coffee grounds to make coffee then we chill the hot coffee. But we tend to make more fresh coffee here while Europeans tend to make more instant coffee.
To serve we pour some in a glass and add chipped ice.
We also tend to add flavors to our frappé in the States. We can't leave a good thing alone - we have to tinker with it to make it more sellable.