Simple Door Intercom

This intercom circuit suitable for accompanying¬† door bell. This circuit uses the speakers both as microphones and as loudspeaker. This intercom is made simple by using only a single amplifier IC LM390 to serve two-way communication. This circuit is based on master controlled half-duplex operation.¬† With LM390, a 6V battery supply would produce loud enough volume. Here is the schematic […]

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Powerline Carrier-Current Remote Control or Intercom

Using 567 IC tone decoder/detector, we can build a remote control and or intercom. This circuit can be used to control a relay, or to carry an audio signal (intercom) through power-line wiring. Here is the schematic diagram of this remote control/intercom circuit: The relay will be activated if you inject a 100kHz tone. This can be used to control […]

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