Bidirectional Intercom by using LM386 IC

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Intercom Circuit is a bidirectional communication application for the ease of not-so-far-distant communication. The intercom is simple and easy to build a low-cost circuit using a single amplifier IC LM386 and a 2N3904 transistor. IC LM386 is most commonly used by electronics hobbyists in audio circuits as amplifiers.

LM386-Low-Voltage-Audio-Amplifier-250mW-or-6V

Hardware Components

The following components are required to make a Bidirectional Intercom Circuit

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1.ICLM3861
2.Transistor 2N39041
3.Switch DPDT1
4.Speaker 2
5.Battery 9V1
6.Switch1
7.Variable Resistor 5KΩ, 10KΩ1,1
8.Resistors270KΩ, 27KΩ1,1
9.Electrolytic Capacitor1µF, 100µF, 470µF1

LM386 Pinout

LM386-Pinout

For a detailed description of pinout, dimension features, and specifications download the datasheet of LM386

Bidirectional Intercom Circuit

Working Explanation

The intercom circuit integrates two 8Ω speakers both functioning interchangeably as a microphone and listening equipment. Hence, for switching between the two actions i.e. listening and speaking, a Double Pole Double Through (DPDT) switch is connected. Also, for the purpose of controlling the volume of the speaker, a 10kΩ potentiometer is used along with a 5kΩ variable resister to obtain the total gain. Moreover, in order to increase the gain from the default value of 20 to 200, capacitors are used.

Applications

To communicate outside of

  • The campus of the School
  • The building Offices
  • Homes