Interface for telephone answering machine tape recorder - comprises tone decoder and switching circuits allowing two ordinary tape recorders to answer telephone call

摘要

An opto coupler converts the rining signal into dc for a transistor timing circuit to control an opto coupler and trial to switch the mains power to a recorder. This plays a tone recorded on an endless cassette tape from an oscillator. When completed the tape is rewound ready for the next communication. - The tone signal is calibrated and amplified and is routed via a tone decoder which converts it to a logic level. The tone is also transmitted onto the telephone line. The logic level signals are routed via a counter which sends pulses to latching and unlatching circuits which ensure that power is applied to a second recorder. The line relay is operated to record the communication which is routed via an impedance matching circuit.