Transistor intercom circuit.
Description.
Here is a simple but effective intercom circuit that is based fully on transistors.The circuit is based on a three stage RC coupled amplifier. When the pushbutton S2 is pressed, the amplifier circuit wired around T1 & T2 becomes an astable multivibrator and starts producing the ringing signals. These ringing signals will be amplified by the transistor T3 to drive the speaker. When the push button S2 is released the circuit will behave as an ordinary amplifier and you can talk to the other side through it.
To construct a two way intercom, make two identical copies of the circuit given below and connect it according to the given connection diagram. 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.
can use of 12V source be used instead of the design 9V?
serach
circuit
i would like to get the introductory aspect of this transister intercom
can someone give a detailed explanation about the working of this circuit
I can not find Q3( BEL 187 ) in the data shit , could you please introduce it’s equivalant.
thank you
Dear Deepika Q1 & Q2 are amplifiers to increase the signal level from the condenser microphone M1. Q3 is the power amplifier to drive the speaker. For calling the remote person Q1 & Q2 act as a flip flop oscillator by pushing the S2 switch, its signal is amplified by Q3 and fed to the remote speaker for attention. Please see the inter connecting diagram for the position of speakers. Enjoy reading Circuits today try to assemble them you will love them.
how i connect these two circuits
there is no connection show b/w these circuits
i’m confused about connecting s2 on the board i cant’ figure out how it should be i need an answer as soon as possible its my graduation project so please help…..
hello sir,is the switch S2 is like the home bell? and will i be able to use it as a home intercom(any range problem)?
i am waiting for your reply as early as you can.thanks
Hi Saad it is just a bell push switch (like home bell switch). You can use it as door phone. up to 100 feet or so you should not face any problem. cable should be atleast of 1sq mm cross sectional area
pls can u send me how i can connect the two circuit along eachother an how i can add amplification ecause i intend to use both a.c and d.c power supply on my cicuit, thank u
can we replace Q3 by Q2.
Hi neelavathi use 2N1711 or BD135 or 2N2218 or 2N2219 for Q3 it required higher capacity transistor than BC548.