Thursday, September 3, 2009

Electronics Hobbyist Checklist

Time to document some of the mistakes I have made more than once so I won't ever do them again:

  • Mirror the BOTTOM layer of the PCBs before milling them! I just finished a perfectly milled double-sided board. Too bad I forgot to mirror the bottom of the board (and did mirror the top of the board). Unfortunately now all its good for is a reminder not to do that again. From now on, I'm putting some text on the top and bottom of the board layout so I'll always know that the board is mirrored correctly before milling.
  • Include the mounting holes in the board layout from the beginning so you don't have to move things later to accommodate them.
  • Don't route on the top layer to parts that you cannot solder on the top unless you have plated-thru holes. If you're milling the board, you don't have plated-thru holes.
  • Include test points on PCB designs where you need them. This is especially important when using surface mount components that you cannot clip a lead to. I use two .100 spaced holes and loop a spare lead through the holes to provide an easy place to clip a probe.
  • Include jumpers in power inputs where you might need to measure current. Not necessary if you include a power switch (or cheap power jumper header)
  • No matter how well you checked the solder joints and traces, use a current limiter on the power supply when you first connect the circuit. You MUST keep the magic smoke inside the devices or they will not work.
  • Surface mount components = easier layout, more compact boards, and less holes to drill. It takes a little more practice and patience to solder them, but they really do have some benefits to hobbyists too.
  • If possible, use a diode on the power input for polarity protection.

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