Transistor switches for selecting program signals in a wired broadcasting system
Multiple input signal digital attenuator for combined output
Miniaturized scan within a pulse sonar
Methods and apparatus for transmitting electromagnetic radiation for illumination and communication
Programable low impedance digital attenuators
Balanced impedance coupler
Audio distributing system
AbstractController for use at a listening station in an audio distribution system for selecting a channel of audio programming. The controller has input attenuators for reducing the level of the audio signals, an output amplifier, and a controlled analog switch connected between the attenuators and the amplifier for passing the attenuated audio signal from a selected channel to the output amplifier. The amplifiers have a relatively high imput impedance, and the amplifiers in the distribution system operate at a relatively low power level. The attenuated audio signals are impressed upon a voltage centered in the operating range of the analog switch. In the disclosed embodiment, the analog switch comprises a multiplexer, a counter connected to the address inputs of the multiplexer, and a channel selection switch for applying clock pulses to the counter to step the multiplexer through the audio channels in a predetermined sequence.