Design of the EPC-9, a computer-controlled patch-clamp amplifier. 1. Hardware.

The EPC-9 patch-clamp amplifier is a digitally controlled analog device for recording currents in membrane patches and in small cells. It has neither front-panel controls nor internal trim adjustments; instead all gain, range-changing, transient cancellation, calibration and other functions are computer controlled. Novel aspects of the circuit design of this instrument are discussed, with special reference to the issues of allowing computer control of all functions.