Electrical pulses are synchronized to the power line frequency. Three frequency modes are available - the 60Hz line frequency, a 10Hz fixed frequency, and a variable output that allows sub-multiples of the line frequency from 1Hz upward to be selected. Spark transmission to the experiment is controlled by a remote trigger button on a 91cm long cord. The spark voltage output depends on the length of the spark gap, and can be up to 30kV. Continuous line frequency operation is limited to 45 seconds per recording because of heat generation. Reset time is 10 minutes. Frequency stability is ±0.1% for normal power line quality. Requires 120VAC/60Hz, 240VA max. Dimensions: 10 x 26 x 20cm.