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Topic: Intercom circuit (Read 198 times) previous topic - next topic


May 18, 2019, 09:51 pm Last Edit: May 18, 2019, 09:53 pm by tjones9163
Hello, i am going to try and build an "intercom circuit" that i will post below. I also have a pic of my sound sensor board that has 4 pins ( +,-, D0,AO).
My question is the circuit calls for a two pin electret microphone and i have a four pin and dont want to de-solder it. How should i hook the sensor board up according to the schematic?


Not withstanding that this is a forum for the Arduino and your project seems to have nothing to do with Arduino...

Your 'sensor' seems to have a microphone on it of some kind plus something else. Is it an amplifier? An A to D converter? Maybe someone else will recognise it but I don't. A link to a data sheet or some other information that would tell us what it was would help.

Your circuit demands an electret microphone so an electret microphone is what you need to get, either unsolder the one from the board you have, buy one or get one from some old piece of equipment. I work in telecoms, I can tell you that phones generally use them.


those sound sensors are just that - not meant to be used for quality *audio* transmission.

you can detect hand claps to switch things on and off, but i doubt you can use it for voice transmission (which is what i understand by "intercom").
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That's a sensor board containing a microphone.

The A0 output is some kind of analog signal - the microphone also produces an analog signal - but without further information it's not sure what that analog signal is. I wouldn't be surprised if it's some kind of level envelope rather than actual sound signal.

You better just buy a separate microphone. Or break open two of your old mobile phones and harvest the microphone out of them. Usually much smaller than the one on that module, which may be a plus as well.
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Schematics for similar boards show the analog out is taken from the electret mike though a capacitor.

The OP can use his board and the analog out to connect to RV1 in his circuit. The board already has R2 and C5 on it, so those are not needed. Grounds on both must be connected.

You do have to power your mike board with 5 volts to bias the mike.



Thank you for the response. I have actually taken an old Bluetooth speaker that has a mic, and used it in my circuit and it works pretty good. It is not very loud but it does amplify my voice.

A very weird thing happens when i remove RV1, my speaker picks up a radio nearby (not im my apartment) but it does amplify, what sounds like a Spanish talk show when i remove potentiometer. Is the jumper wire that i have connected to pin 3 picking up radiowaves maybe determined by the length of wire and my lm386 is amplifying it?



Is it possible then to add a variable inductor where my wire is and create a crude radio receiver?

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