Audio Waveform Generator

This Audio Waveform Generator appeared in Maplin Projects Book - 48 (PDF of article included). I created my own board using eagle software (eagle files included) and used OpenScad to design a suitable case for it.

The board shown in the image is my first attempt. The V2 board included in the associated files fixes the problems of the Frequency pot being wired back-to-front, the capacitors C13-C16 hitting the nut that holds the attenuated BNC socket, moved the power connector because it was hitting the battery holder and added notches for the cables from the BNC sockets.

The 4 trimpots are soldered on the back of the board so they can be adjusted easily. The power and output connectors are also on the back of the board.

I used 1/8W resistors throughout to keep a 7mm hole spacing. You can use 1/4W but they will be a tight fit.
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Assembly
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For the PCB mounting posts, drill holes out with 2.5mm drill and create a thread with a 3mm tap. I used 6mm M3 screws to hol