Abstract: A resistance network is provided for synthesizing a non-linear logarithmic response in the resistance of the network comprising a potentiometer from the change of the resistance of the potentiometer. The network additionally comprises a set of resistors. The potentiometer allows the resistance of the network to be varied, while the network manipulates the current in such a fashion that the input current required to produce a desired output voltage is a linear function of the resistance of the potentiometer. Incorporated into a current overload detection circuit, this allows an even spacing of the desired trip current settings about the dial of the potentiometer.

Abstract: A fuse blown detection circuit for use in conjunction with the control transistor output circuits of a programmable controller which provides low leakage after the fuse is blown. The detection circuit comprises a pair of voltage dividers and a diagnostic triggering device forming an H-bridge network connected across the terminals of the fuse and a blocking diode. When the fuse is blown the voltage levels defined by the dividers change to activate the trigger device and enable a diagnostic signal indicative of the fuse blown condition while the blocking diode prevents current flow back through the control transistor and output circuit.