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How to make a direct microphone to speaker circuit? Answered

Hello all,
I recently wanted to develop a circuit which picks up voice signals from a microphone and outputs it to a speaker.
As I recently started learning to build circuits, I was hoping to get a few inputs and tutorials on how to build one in a step by step manner.
Please help by giving instructions and not a circuit diagram as I am still learning.
Thanks for all your help!
Regards,
Microtest

9 Replies

user
iceng (author)2014-10-07

You can see physically how this circuit is put together.

The author called it a radio receiver BUT he put the wrong picture on the page.

Clearly it is a fixed volume three transistor audio amplifier.

I back traced it and guessed at the capacitor values and the transistor type.

It may need adjusting but should work with an electret mic

If yours is a three wire mic let me know and I can change the input.

The reason I like this pic is it zooms so well for a neweby to see the wire placement....

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user
Etronix (author)iceng2017-02-10

Would this work using an 8ohm speaker?

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user
iceng (author)Etronix2017-02-11

Not as well with a puny TO-92 case 2N3904 driver transistor...

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iceng (author)2014-10-04

You can use a speaker to an identical speaker just straight wiring, NO electronics, No batteries !

Talk into one and hear it in the other in another room.....

BTW this set up is by-directional ..... Works either way and because there is no amplifier in the path there is no feedback Squeal .. Ever.....

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rickharris (author)iceng2014-10-04

You can use 2 paper coffee cups connected with a length of string as well, but it isn't going to work very well unless it is a straite line.

However the speaker to speaker works because the output of a speaker is much larger then the output of a microphone.

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user
iceng (author)rickharris2014-10-04

I was wondering who would pull that line out :-)

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rickharris (author)iceng2014-10-05

never one to fail you :-)

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user
iceng (author)iceng2014-10-04

Some details of speaker operation.

The reason the receiving speaker is quieter is the resistance in the connecting wires .... So use heavier gauge wire.

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rickharris (author)2014-10-04

No - You can't directly drive a speaker from a microphone. the output from the microphone has to be amplified by an electronic circuit. Lots of audio amplifiers on line if you search.

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