Circuit Diagram

The brief with this project was to produce cost effective electronics that could be assembled by a small, informal PCB manufacturing plant based in India, repaired easily, and producible with the minimum of setup.

This board could be made single sided by incorporating three jumpers. As it is somtimes difficult to communicate what jumpers are, as a part in a BOM, the jumpers were made 1 ohm resistors.

The mosfet driver used in this board is a fairly generic pinout part, and the mosfets themselves are not expensive or high performance parts, but they have been given good heatsinking - emphasis on easy parts purchasing, and easy production.

Reverse polarity "protection" of some sort was required, but we could not afford the losses of a series diode, and we needed to keep the price down. The compromise selected was to place a standard rectifier diode reverse biased across the supply, so if the supply is connected with reverse polarity hopefully most of the remaining circuitry is protected, although D1 itself is likely to sacrificially go short circuit doing this job.