• jumper in this position selects the lm7805 chip for board power (instead of the download/host cable's 5v power).
  • input supply (black=gnd) for 3.3v logic. anything that is 4.5v and higher works well here. the grey test clip is on the 3.3v test bus and going to my DVM, showing exactly 3.3v out.
  • ground test post, on the 3.3v side of the board.
  • 3.3v test post. should always be a clean regulated 3.3v if you clip a meter here.
  • output of the controller. this has 2 wires for 3.3v isolated power and then 4 leads for opto-isolated collector-output (pulled up by 1k resistor network).
  • this black marker dot reminds me that this is the 'minus side' of the cable.
  • more black marker. each board is unique and I've found its a good idea to put reminders on what the important wires and polarity is.

DIY: testing the 2 PSUs

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more progress; with a hidden 3.3v lm1117 underneath the board, soldered to its own isolated heatsink plane (which, btw, is NOT ground. harumph!)

the left side is at 5v and the right side will be at logic 3.3v. each has its own ground and its own B+ supply.

the top led is really red, but was too bright for the camera to capture well. green is for 5v power and orange is on the arduino pin13 to show activity.

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