The Voltage-clamp Apparatus Assisted by a 'current Pump'

A current pump is described, which is attached to the last stage of the 2-microelectrode voltage-clamp apparatus. Thus a voltage-to-current conversion independent of the impedance of the current microelectrode is obtained. In this way it is possible to pass relatively large currents through the current microelectrode and in the same time to have a stable negative feed-back system.