Monday, January 6, 2014

CryoBUG: New Controller Board Assembled

I got the new controller PCB's late last week, and assembled one over the weekend. Best part was that when I bench tested it, everything appeared to function perfectly (what a relief).

CryoBUG Controller with optional OLED Display connected

Today I installed this into CryoBUG and took it for a test run, and was pleased to see that nothing out of the ordinary happened when controlling the actual compressor. One of my concerns was that the switching currents might upset the microcontroller, causing it to randomly reset. So for that reason I made sure to place a couple of power decoupling capacitors real close by.

The only unexpected thing that I noticed when probing the board with a volt meter, was that the 12 VDC supply drops down to about 8 volts when the compressor relay is powered up. Doesn't seem to be affecting anything though, and since the voltage is about 14+ volts before kicking on the relay, it shouldn't pose a problem (the datasheet shows a must operate at 8 volts). Probably wouldn't be as bad if I had implemented full wave rectification, and I might look into this later just for grins (this might mean a possible Rev 2.2).

Since the 5 VDC power draw is very small, I could most likely eliminate the heat sink on the regulator.

I really do like the OLED display. It looks very bright and sharp. But unfortunately no place to put it on this build.

Update 1/8/2014...

I assembled a second board and decided to post a couple of close up shots.

Top View
(click on Image to Enlarge)

Bottom View
(Click on Image to Enlarge)

And as I suspected earlier, the heat sink is not needed, so it was left off of this build. As can be seen, this is a pretty simple and small controller board. And yet for all its simplicity, it has a multitude of possibilities. All that's required is some creative programming of the on-board microcontroller.


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