The Model 1212 current preamplifier is designed as a low cost, general purpose, bench top instrument to provide a high performance detection system for small ac and dc currents. The 1212 operates with a virtual ground at its input which mitigates unpredictable high frequency roll off due to input cables and stray capacitance. The zero input impedance also allows photodiode detectors to operate linearly over a very wide dynamic range and photomultiplier tubes to operate with minimal distortion.