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Old 11-17-15, 10:34 AM   #12
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Quote:
Originally Posted by jeff5may View Post
I used a "freebie" power board out of a donated portable dehumidifier for a relay shield equivalent. The board also has a regulated 5VDC power supply built into it that feeds the Uno board through the USB plug.
Perfect! Any time you can source your parts from the scrap pile, or the donor equipment, you're way ahead. I recall seeing similar boards in the 230v/50Hz split units I dealt with overseas. The window units I've played with here in the US were all running on simple capillary-bulb close-on-rise mechanical switches.

I'm mentally breaking down that board: Transformer to bring down the mains voltage... four discrete diodes are the rectifier... Perhaps the TO-220 package to the upper left is the LM7805 with a few filter caps surrounding it for 5v power. I imagine that little DIP 16 sized IC in the upper right quadrant of the first picture is some kind of gate array or buffer to interface the relays with TTL signals... or perhaps some other low complexity IC? The white header at the top is the control interface. ...and some kind of piezoelectric alarm/horn in there too? I would presume the large black square relay is the compressor. The 3 blue relays are fan motors, etc.

Good stuff.
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