Abstract: A thumb wheel controller that converts the output of a thumb-wheel actuated potentiometer to a digital representation of the thumb-wheel position. The controller includes a pair of operational amplifiers whose linear ranges coincide with the thumb wheel range segments above and below a central dead band and whose output voltage ranges correspond to the digital range of the controller output.

Abstract: An audio filter circuit is formed from a pair of cross-coupled, symmetric filters, each filter having a first stage comprising a single-pole, inverting low pass filter followed by a second stage comprising a two-pole, non-inverting Sallen-Key low pass filter. The circuit is readily switched between single-ended and double-ended output, while maintaining comparable noise and gain characteristics. The gain of the circuit is readily adjustable over a range of gains.

Abstract: A video amplifier for decoding a digital signal input and providing at least three video brightness levels plus a black level to a cathode ray tube is disclosed. The amplifier includes input logic decoding circuitry for providing control signals to a plurality of switching elements which vary the voltage level of a video output signal. The video signal has at least four discrete voltage levels corresponding to a black, dim, normal, or bright display. The amplifier is preferably mounted on the socket of the cathode ray tube and provides a bandwidth on the order of 75 to 100 MHz.