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22 February 2010
Author: Giorgos Lazaridis
PCB Etching Bath with Heater and Agitation

Worklog - Controlling the heater

If you have read the article about Removing the built-in thermostat of an aquarium heater, you will have notice that the circuit for controlling the heater was built on a breadboard for test. Thus, i had to make first a PCB for this circuit. The circuit diagram along with the PIC program can be found here:

With the Eagle i draw the PCB and etched it in my new tank, with the heater heating the solution! I suppose this can be declaread as the first test run. It needed roughly 6 minutes to etch the PCB. This is the result:

Take a closer look at the marked area. I will sodler the LED digits to the bottom side of the PCB. I have not drilled holes, because i will solder them as an SMD device. For this, i had to bend the pins of the display by hand, as it was a through-hole device. Please, if you have not yet notice the "Februaru", just don't. Here is the PCB with the components soldered:

And this is the bottom side of the PCB with the display:

A base for the heater

As i said before, the heater is for fish aquarium. The base of the heater is 2 suction cups. I had to make a base to hold the heater at the side of my tank. For this, i used a 2cm wide piece of acrylic glass. I bended this piece at the bottom side for the air-bubbles hose. On the top side, i bend it to make a clip, so that the base would kept in place while in operation. Then, i used the grinding wheel to make slots. Through these slots, i fixed the bases of the heater with tie-wraps. I had of course removed the suction cups.

For the base, i will use a long, 2cm wide acrylic glass I bended the bottom side for the air-bubbles hose I bended the top side to make a security clip Almost ready...

These are the original bases of the heater, without the suction cups With the grinding wheel i made slots to fix the bases with tie-wraps The heater can now be attached to the base



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  • At 3 January 2012, 2:58:43 user George wrote:   [reply @ George]
    • looks like time for my 2 cents worth

      For those starting out making pcbs who want an out of the box solution, tank, heater, bubbler,thermometer have a look at kinsten.com.au $AU65 for the complete kit.

      Look up edinborough etch - by adding citric acid to the ferric chloride solution - the copper ions are moved away from the pcb's copper surface much more efficiently than using bubbles.

      Also, when I am only making a quick small board, I put the ferric chloride into a conical(erlinmyer) flask put it in a bath of boiling water from the kettle whens it's above 45C pour it into a plastic bowl & drop the board in & move the ferric chloride over the board with a brush.

  • At 2 January 2012, 18:43:20 user Kammenos wrote:   [reply @ Kammenos]
    • @Skiwee Yes i do use it quite often indeed. As a matter of fact, this is the setup i use to make all my PCBs and never failed me.
      I plan to make a bigger one, like 4 liters or maybe bigger. So i have some questions that maybe you could answer. To avoid flooding the comments board, i have open a thread in the forum. Please visit the following link:

  • At 2 January 2012, 18:17:46 user Skiwee wrote:   [reply @ Skiwee]
    • I like the setup, you seem to use it quite often.
      In the second video you agitate your etching solution. There\'s no need for that it\'s just copper sediment and waste from previous uses (it\'s best to hand this to your local hazardous waste management/company).
      The solution should have a dark orange/brown \"oily\" appearance.
      example image; http://upload.wikimedia.org/wikipedia/en/thumb/8/8c/Iron%28III%29_chloride.JPG/551px-Iron%28III%29_chloride.JPG
      for more information on chemicals a quick MSDS search on google goes a long way.

  • At 4 July 2011, 15:49:45 user Lambrosz wrote:   [reply @ Lambrosz]
    • Were did you find the air pumb and the heating resistor ... Also an other thing is about the thermistor is PTC or Ntc what you suggest!
      Very nice job !! ... i Would like to build one too :-p
      Welcomes from Crete!!

  • At 28 February 2011, 13:01:30 user Fung wrote:   [reply @ Fung]
    • What will happen if the process is overtime? (ie The board is done but not taken out on time)

  • At 2 January 2011, 8:08:49 user Kammenos wrote:   [reply @ Kammenos]
    • Hi Das,
      the bubbles accelerate the procedure. They do not stick on the PCB, and even if one bubble sticks on it, there will be another bubble to remove it within a moment. The do a great job.
      I do not know if a pump could do a better job, i have not test it yet. But i do know that it would be an ugly job to clean it. Copper remains would destroy the pump if not used. It had to be cleaned regularly to keep it clean. And moreover, why risk circulating the messy etchant outside the tank, if the bubbles work that fine?

  • At 1 January 2011, 17:37:49 user Das wrote:   [reply @ Das]
    • wont the bubbles stick to the PCB during the process and hence reduce the effectiveness??

      since you already used a fish tank air pump, why not a water pump to circulate the solution? if a pipe with holes along the length is made and one end sealed off, that would help distribute the solution even better.

  • At 27 December 2010, 22:36:00 user herctrap wrote:   [reply @ herctrap]
    • ok i am waiting

  • At 5 December 2010, 22:23:23 user Kammenos wrote:   [reply @ Kammenos]
    • herctrap you are so right. I had totally forgotten it. I had the masters given to a friend to make the video, but he never did it and did not inform me. I forgot all about it. I will search for the masters (although i am sure that i will not find them again) or i will run a new video. thanks for noticing reminding me.

      By the way, my goal was to have a video for each project or circuit (and sometimes for theories and experiments). The fact that you noticed that this page should have a video, makes me double happy. This proves 2 things for me: first that people want to see videos of the circuits and the projects (and so my efforts to make them is not useless), and second that people do know that in this site they expect find videos, and that something is going wrong if there is no video in a project. When i upload the video i will post it in the RSS. Thank you again.

  • At 5 December 2010, 13:49:09 user herctrap wrote:   [reply @ herctrap]
    • Where is the video for that?

  • At 14 April 2010, 21:00:05 user Kammenos wrote:   [reply @ Kammenos]
    • I put the sensor in a plastic hose and sealed it with heat glue. The schematic for the thermostat is here:


  • At 14 April 2010, 19:48:09 user k.z. wrote:   [reply @ k.z.]
    • Where you put the NTC? inside the heater tube, or in the tank wall? And for the eagle files for the thermostat? Thanks a lot. Regards.

  • At 6 March 2010, 15:08:10 user Kammenos wrote:   [reply @ Kammenos]
    • At the moment, i etch without ventilation, but i have an old vacuum that i will convert to ventilator. I really had no idea that rust could occur, although now it sound normal to me! I was considering the ventilation for health reasons only. Thank you for the info Vern!

      BTW. Which chemical you use for etching?

  • At 6 March 2010, 14:55:01 user Vern Smith wrote:   [reply @ Vern Smith]
    • Have you considered using a ventilation system to control the fumes? Nasty results in the shop..instant rust!!

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