I need a simple audio circuit (intercom)

[jbelectric777]

can someone post me a schematic for a basic no frills intercom. i just need to understand how to connect the the microphone element to amplify enough to drive a small speaker. thanks in advance, jim

 

[ronv]

This IC is about as simple as they get. you can find them at radio shack. What kind of microphone will you use?

https://www.electro-tech-online.com/custompdfs/2011/03/LM386.pdf

 

[Boncuk]

Hi,

this a full duplex intercom requiring not "push to talk" button, hence it is sabotage proof.

The master unit uses a "private" switch for no outgoing conversation of the house. Anyone calling can be heard despite that switch.

The master unit has a pot adjustable volume control

The slave unit works with a fixed volume determined by the voltage diver R10 (4.7K) and R11 (10K).

The own voice is not audible on the units. Therefor no acoustic feedback can occur.

Boards are purely single sided and measure 48X86mm (1.9X3.4")

Boncuk

 

[jbelectric777]

i was gonna use one of those radio shack microphone elements. what do you suggest? so that one little IC has all that in it and ready to go? i always wanted to get into more audio stuff but was always sidetracked.

 

[jbelectric777]

im gonna post a schematic before i make this board if u guys will give it a look, thanks for all the info ,,,,, jim

 

[ronv]

Sure the little electret microphone would work. The IC is just the "stuff" in the triangle. You need the rest of the capacitors, resistors and potentiometer to go with it. A 12 volt wall wort power supply would power it.
It will not be very loud ~ 1/2 watt but that is probably enough for an intercom.
Do you want to talk in both directions? If so something more like Boncuk posted (or a push to talk switch) would be required. If you decide to build it use the gain of 200 schematic and use a 47 Ufd. cap for the one they call bypass.

 

[Boncuk]

Hi ronv,

I suggest you study the data sheet of the TDA7052.

It provides 1W power output, loud enough for any intercom.

Boncuk

 

[audioguru]

A 12V supply will blow up a TDA7052 amplifier IC. Use no more than 6V.
A 12V supply will cause an LM386 amplifier to get very hot without increasing the output power much more than with a 9V supply.

 

[ronv]

Boncuk, I was addressing the lm386.

AG is right. no need for the higher voltage.