A general-purpose pulsed field controller

A pulsed field controller compatible with various types of electrophoresis tanks and power supplies is described. The system is based on a high‐precision timing circuit, with an output isolated from the main high voltage supply, and four high voltage transistors. The switching time is programmed manually between 5–160 s. With a transverse alternating field electrophoresis system, intact yeast chromosomes could be completely separated after 24 h.