Abstract: A programmable power supply having a plurality of channels wherein each channel is adapted to output a selectable DC voltage, AC voltage, DC current or AC current. Each channel is adapted to select a DC reference signal or an AC reference signal and to scale the selected DC reference or the AC reference to output the selected signal. The outputted selected signals are monitored to provide a monitored channel signal indicating the value of the selected signal. The programmable power supply outputs monitored channel signals for each of the channels in a human perceivable format such as a display or printed format. At least some of the channels are adapted to be connectable to a temperature probe which outputs temperature signals and, in this embodiment, the temperature signals are monitored to provide monitored channel temperature signals, the monitored channel temperature signals being outputted in a human perceivable format such as a display or printed format or both.

Abstract: A passive conference bridge is coupled to telephone lines through pairs of panel mounted plug-in jacks to establish conference call connections with balanced input/output impedances. Test equipment is plugged into the jacks for connection to the bridge circuit and/or telephone lines. The telephone lines are disconnected from a leg of the bridge circuit through one of the jacks of each pair and a terminating resistor is thereby inserted into the disconnected bridge leg.