A four‐channel electronic switch and amplifier designed for direct connection to the deflection plates of commercial oscilloscopes are described. The system permits the simultaneous presentation of four signals and responds uniformly to d.c. voltages and a.c. voltages with frequencies up to 100 Kc. It may be used for visual observation in this range, for film recording of the wave form of individual cycles up to 1 Kc frequency, and for recording the modulation on carrier signals with frequencies up to 100 Kc. A discussion of the principles, circuit, and results are given.