After building a hodgepodge VLF receiver from http://www.techlib.com/electronics/vlfwhistle.htm, I decided to turn it into a PCB on Sunday. This is about 4 hours of work, from schematic entry to etched and populated board. This is the “Hum Bugged?” version, and it is very clean outside. I had to add some negative feedback for high frequency signals (1nF + 91R), as the AD712 wanted to pick up everything and go into oscillation.
(btw, admins, it would be nice to be able to upload SVG files)
Note that I’ve flipped the through-hole components so that I can use a single-sided board.
This pre-sensitized board stock has “SEPT 1992” printed on it, but it still works like a champ!
Holes were drilled with “10Pcs PCB Print Circuit Board Carbide Micro Drill Bits Tool 0.3mm to 1.2 mm NEW” from the ebays, $7 a set. They look like this:
Be careful! I broke the right-sized one by applying lateral force.