LM386 wired intercom circuit diagram

This is a wired intercom circuit that uses the audio power amplifier integrated circuit LM386 as the main component. The transition of intercom status can only be controlled by the host, and the extension has no control function. The position of S1 shown in the figure is for the extension to send calls to the host; if S1 is moved downward, it becomes the host to send calls to the extension. There is only one loudspeaker BL2 in the extension, which serves as both a microphone and an earpiece. The same goes for the head unit speaker BL1.

LM386 is used as audio amplification. The ③ pin inputs the signal and the ⑤ pin outputs the signal. The capacitors connected to the ① and ⑧ pins can adjust the circuit gain and can be used. The power supply voltage is available from 4.5-9V.

The component parameter values ​​are as follows:

It is best to use twisted pair wires for BL2 lead wires to reduce interference. The disadvantage of this circuit is that the extension cannot call the host and the standby state consumes power.