Accession Number : ADD006283

Title :   Double Button Spurious Signals Prevention Circuit.

Descriptive Note : Patent Application,


Personal Author(s) : Kelleher,Robert B , Jr

Report Date : 04 May 1979

Pagination or Media Count : 17

Abstract : An analog circuit prevents spurious signals when two buttons are simultaneously pressed in a digital signaling telephone keyboard (telephone console). The analog circuit includes a group of pull-up resistors, with one resistor connected to the high switch contact associated with each button; a responsive resistor connected between the pull-up resistors and a voltage source; an operational amplifier whose inputs are connected to a threshold reference voltage and to the responsive resistor; and a circuit, including a zener diode, connected at the output of the operational amplifier for TTL voltage compatibility. (Author)

Descriptors :   *Patent applications, *Telephone equipment, *Spurious effects, *Switching logic, Digital systems, Electronic equipment, Electric switches, Push buttons, Telephone signals, Fixed resistors, Operational amplifiers, Transistor transistor logic, Prevention

Subject Categories : Non-radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE