PIMD V2

Reworked the schematic to add an OpAmp (OPA2365).

Added A0 to the signal output so I can look alternative signal processing options.

This board uses an IRL540 instead of an IRF540, which reduces the MOSFET voltage drop.

Here is the assembled board before testing: 

Two Signal Processing Approaches

ADC

First we could go the ADC route, the board is setup for this.

With a 1MHz clock, we can do samples every 13 to 14 us without losing accuracy.

We can trade faster conversion for accuracy.

Timer

The current approach measures the time the signal takes to decay to a specific test voltage (~40mV).

We could expand the number of voltage tests by controlling the reference voltage using a R-2R resistor ladder. Unfortunately I did not make provision for this with this board.

TBC ...

AlanX