Allow make the following ammendment:
The testing I did was using an "Improved Howland Current Pump" configuration with a 15 V supply and impedances of less than 100K (max 150 uA). I wasn't testing at the upper end of my impedance limit.
However, even using resistances much lower...
Please help!
I'm trying to build a constant current source that will drive between 5 uA and 200 uA through a variable impedance (50 kohms to 500 kohms) to ground. Once wired, the system will not need to be adjusted. (Multiple set-ups for different current levels will be made). I need an...