Audio preamp circuit for microphone input. (solved)

[Jim0000]

I have a small audio amplifier designed for automotive application. I want to use it to make an electronic stethoscope of sorts. I plan to use a cheap microphone from Banggood and drive a small speaker.
The purpose is to assist me to locate vacuum leaks while vacuum bagging composite parts (fibreglass, epoxy and other composite materials).
The plan is to place the microphone over the vacuum line where it exits the vac bag. If there is a leak, the air rushing into the hose can be heard when I put my ear close. However, the leak might be up the opposite end of the bag, requiring my attention while listening at the same time.
I figure a device like this would be a great aid for this.

Accordingly, can somone direct me to a simple mic pre-amp circuit to drive and little audio amplifier at line level please?

Jim.

[Zero999]

What sort of microphone is it?

[alsetalokin4017]

You'll probably be using an electret mic since they are ubiquitous, cheap and quite sensitive. There are a bazillion circuits that will do what you want, from extremely basic to quite sophisticated.


For example:
https://www.electronics-lab.com/project/low-noise-mini-electret-microphone-preamplifier/

[tooki]

If you're gonna order from China anyway, why not just order one of those little mike preamp boards that use a mike amp IC, and either have a mike on the PCB already, or include one you can mount off-board?

Or, instead of using sound, why not use a pressure sensor on the vacuum hose? If there's a leak, the vacuum will not be as strong as if the seal is airtight.

[Jim0000]

Thanks for the replies.
I found one here:  http://www.circuitdiagram.org/microphone-preamp-circuit.html