Paystation transmitter ground detect circuitry

Details Paystation transmitter ground detect circuitry Paystation transmitter ground detect circuitry

1988-07-01

1989-04-11

Lev, Robert

Telephonic communications

With check operated control

Fraud or interference prevention

379155, H04M 1700

Patent

active

048213136

ABSTRACT:
A ground detect circuit for use in telephone paystation consisting of a comparator circuit which compares the voltage across a telephone transmitter included in the paystation to prevent users from fraudulent use of the instrument by grounding the handset transmitter to signal the central office that initial rate deposit has been made when in fact it has not. The ground detect circuit upon detecting the presence of ground at the transmitter generates a signal which can be utilized to disable an associated calling device.

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patent: 4759054 (1988-07-01), Mellon

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