Homemade Phone with Basic Electronic Circuits

This project about communicating two people with basic electonic circuits. This is my Electronic circuits lesson's project. I want to make a video about it.

Description

Here is a simple but effective intercom circuit that is basedfully on transistors.The circuit is based on a three stage RC coupledamplifier. When the pushbutton S2 is pressed, the amplifier circuit wiredaround T1 & T2 becomes an astable multivibrator and starts producing theringing signals. These ringing signals will be amplified by the transistor T3to drive the speaker. When the push button S1 is released the circuit willbehave as an ordinary amplifier and you can talk to the other side through it.

To construct a two way intercom, make two identical copies ofthe circuit given below and connect it according to the given connectiondiagram. The stand by current consumption of this circuit is around 20mA.

Circuit diagram with Parts list

Connection diagram

Notes

• Assemble the circuit on a good quality PCB.

• Use 9V PP3 battery for powering the circuit.

• The Mic M1 can be condenser micro phone.

• Use push to ON type push button switch for S2.

• Use a slide switch for switch S1.S1 can be used to power the circuit.

BEL 187 equivalent 2N2222, 2N4401, BC 548

You can replace BC548 with BC546, BC547, BC549, BC550

Components

How to Make