lead. Either the PROBE GND connector, or the front panel GND must be connected for proper operation. Usually the PROBE GND connector is tied to the indifferent lead. If you desire to have the current constrained to a known path you may want to place the GND elsewhere. Actual GND placement depends on the application.
The current Model 3000 Headstages are furnished with short interconnects designed to mate with any metal electrodes that terminates in Cooper/Wire-Pro/Amphenol style Reliatac 220-P02 connectors. To use glass micropipette electrodes with the Model 1800 headstage, a compatible microelectrode holder should be purchased. Any pipette holder with a 2 mm pin can mate directly with the headstage without the use of the interconnect. Older Model 3000 headstages (sold prior to March 2013) accept slightly smaller pins, and can mate directly to 1.6mm pin holders.