Analog circuit works until a I hook to Adc.

[jnnewton]

I have an analog circuit consisting of a instrumentation amp and a non - inverting buffer amp. everything works until I hook the output from the buffer to the adc input of my microcontroller (dspic30f4011). The voltage drops from 4 volts down to .5 volts. Is there something I am doing wrong, or i just need to up the gain?

 

[Nigel Goodwin]

I have an analog circuit consisting of a instrumentation amp and a non - inverting buffer amp. everything works until I hook the output from the buffer to the adc input of my microcontroller (dspic30f4011). The voltage drops from 4 volts down to .5 volts. Is there something I am doing wrong, or i just need to up the gain?

I would suggest you have the PIC I/O pin set as an output, and set LOW.

Set the pin to be an analogue input.

 

[jnnewton]

You are correct. Thank you.