We have modified the VIC-E analogue input circuit to include an initial potential divider of 1.2K and 51K, the signal is fed through the 1.2K and into the PIC ADC and one end of the 51K which is joined to ground. This gives a stronger ground pull down, and protects the PIC from excessive input voltages via the 1.2K resistor. This does of course effect the full scale output at 5V input, but I have picked these resistor values so that full scale is now approx 4000 instead of 4095.
