How to; piezo, preamp, laptop

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[FONT=DejaVu Sans, sans-serif]Hi chaps,

[/FONT] [FONT=DejaVu Sans, sans-serif]I got pretty basic request if you please.

[/FONT] [FONT=DejaVu Sans, sans-serif]Can some one tell me how to use a Kemo M040N pre amp, to connect a piezo mic to a laptop?

[/FONT] [FONT=DejaVu Sans, sans-serif]Piezo mic got a 6.3 mm male mono jack. The laptop got mini female jack.[/FONT]
[FONT=DejaVu Sans, sans-serif](I got everything else; female 6.3 mm mono jack, male mono mini jack and 9V battery. Just not sure how to do the wiring).[/FONT]
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Welcome to diyAudio :)

Hmmm... one possible problem I foresee is that a traditional piezo mic has a very high output impedance, which means that it would normally work into a preamp of high input impedance. This could be a problem.

In the first instance, all you can do is try it and see. Use the first option (dynamic mic) and see how you get on.

If you are not sure on the connections then ask :)

The battery has to be connected with correct polarity to the plus and minus symbols.

The battery minus is the common 'ground' connection for both mic and output.
 
Hi thanks for your welcome and your help. I appreciate.

Sorry for getting long to get back to you. (got quite busy lately with work).

I’ve tried your diagram, and it doesn’t work.
I got just loud static noise.

What I’m trying to do is to attach the piezo mic to a mechanic watch. And using a computer timegrapher, read the watch performance.
When I tried all this on Audacity (audio software), I could heard the tick-tack but very weak, there was quite loud static noise.

Do you have any other idea?
Do you think this piezo mic will not work on this pre amp?
 
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The impedance issue I mentioned could be a problem with it not working. Piezo mics really need to work into a very high impedance (Meg ohms) and this preamp as I recall had an input impedance of around 47k ohm.

Interesting what you are trying to do :) I once tried something similar many many years ago (before I had a PC) using a mic and a phase locked loop but didn't have much success tbh.

Ideas... you could try making a dedicated mic preamp to suit the piezo, that might be easier than you think if you are able to solder a few components onto stripboard.

If you could actually hear the watch in Audacity then I'm wondering whether you could record it, then modify the file with filters (in Audacity) to cut the noise.
 
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This will mean something to the OP I hope...

This shows the single FET preamp and how it both matches to the impedance of the piezo mic and how it also provides some voltage gain.

The mic is represented by the voltage source at the left. The laptop input is the 'Load' at the right. Labelled on the circuit are Vin and Vout (voltage in and voltage out).

First image is the circuit.

Second image is the input voltage from the mic.

Third image is the output. The phase inversion is of no consequence and is normal. We are not sensitive to absolute phase in any case... if it were music you couldn't tell which was which.

Fourth image shows how a 47k input resistance absolutely kills the output from the mic. To simulate this, R1 is now 47k. Look at the scale at the left.

Compare images 3 and 4 and look at the voltage output. That is what loading the mic with 47k does.
 

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p { margin-bottom: 0.25cm; line-height: 120%; }a:link { } [FONT=DejaVu Sans, sans-serif]Thanks Mooly, I appreciate your help. [/FONT]


[FONT=DejaVu Sans, sans-serif]This is far beyond my skills. Although I could learn the basics to do this project, without doubt it’ll take me time, which I don’t have right now.[/FONT]


[FONT=DejaVu Sans, sans-serif]I have the Kemo preamp that I bought just for this, and cannot use it, and don’t need it.[/FONT]
[FONT=DejaVu Sans, sans-serif]If anyone give me a preamp I could use with my piezo mic, in exchange I would give my new Kemo preamp. [/FONT]
 
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