An inexpensive electronic switch for preventing amplifier overload in neurophysiological recording

A circuit for an electronic switch is described that suppresses large unwanted signals that might overload physiological amplifiers during recording of weak neural signals. The circuit, made from inexpensive and easily available integrated circuits, can be operated from any timer that produces at least a +5 volt output pulse. It operates by connecting a low gain preamplifier to a high gain amplifier only during the signal of interest.