Automatic telephone answering circuit diagram

Posted on Mar 28, 2007

Automatic telephone responder circuit is shown in Fig. FIG IC2 10 seconds voice recording circuit SR9G10A, press the power switch S2, can be built by IC2 electret microphone in

Automatic telephone answering circuit diagram
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put if you want to tell a friend. Before going out to press the switch Sl, static triode VTl, composite pipe collector voltage VCE VT2 composed of about 0.65V, diode VD2, transistor VT3 nonconductive.When a call hit, the phone ringing, ringing signal negative half-cycle so that ICl 4N35 optocoupler conduction, IC2 of PLAYE grounded (equivalent to a falling edge of the negative pulse trigger) while playback, the audio signal all the way to unilateral after the composite tube amplification, the transistor VT2 of VCE increases, VD2, VT3 turn, relay Jl pull, the resistance Rl analog outside line off-hook (telephone DC resistance of about 300 ); another unilateral way audio signals added to both ends of the telephone line, so your friends hear your voice input in advance. When the sound after sowing, the circuit back to the static relay J1 release, the entire state of the circuit corresponds to hang up.

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