Abstract: A universal adapter is mounted, in either of two directions, by way of a pair of pedestals disposed at its extremities to a planar surface, usually a heat sink. It has a cavity, formed at its upper surface and another at its lower surface between the pedestals each for receiving one of various types of power transistors and thyristors. A plurality of lead receiving apertures communicate between the lower and upper surface of the adapter to permit passage of the different configurations of leads from the various power transistors and thyristors. Electrical contacts for connection to exterior circuitry are affixed to the upper surface for some of the various types and to the lower surface for others of the various type. In either case, the contacts are positioned adjacent selected ones of the lead apertures through which the power transistor or thyristor leads are threaded and to which the electrical contacts are connected.