Delivers positive, negative, or bipolar currents. For bipolar delivery, polarity of the output is toggled to the opposite state with each pulse presented to the input. Pulse duration is controlled by an externally applied voltage. Input connector is a standard BNC, allowing signals from any source such as computer D/A or I/O lines to be used. Output amplitude is set on a 3-digit, ten-turn dial as a percentage of the range selected: for example, a setting of 45.6 in the 0-10 mA range translates to 4.56 mA at the output. Accuracy and repeatability are excellent. Designed for subcutaneous stimulation, maximum output voltage at the stimulating electrodes is 36 volts, reducing the possibility of serious accidental transcutaneous shocks. A compliance/ output alarm sounds when the 36-volt limit is reached. Internal circuitry maintains electrodes short-circuited during inactive periods (“electrode exhauster” feature). A385 is not appropriate for transcutaneous stimulation. The 1.2 amp-hour rating of the six heavy-duty lead-acid rechargeable batteries ensures that experiments will not be interrupted by dead batteries even at peak currents. Indicator lights and audible alarms keep the user constantly apprised of battery charge status. These batteries must be recharged by the A382 System Charger designed especially for the A385.