Abstract: A data switching device for use in controlling a D.C. coupled logic signal path for relatively low level data logic signals between coupled Emitter coupled logic devices having a signal input and a signal output, between which are diodes of reverse polarity connected in series wherein the device is inexpensive and solves the problem of high power dissipation. By coupling control potentials to at least the point between the two diodes and the output of the switch via potential dividers the diodes can be biased into a conductive condition allowing the transmission of logic level signals. Variation of the potentials in the divider network can be used to render the diodes non-conductive to block the signal path.