Audio circuit principle (audio amplifier processing circuit)

Audio circuit principle The dual-tone multi-frequency signal decoding circuit is an integrated circuit widely used in key telephones (fixed phones, mobile phones), program-controlled switches, and wireless communication equipment. 1. Dual audio decoding electronic circuit 2. Pin 3 receives the dual-tone multi-frequency pulse signal from the phone. The dual-tone multi-frequency signal is first passed through its internal [...]