Wanted Transformers for piezo discs

[staras]

Hey,

Does anybody have some suitable transformers for piezo discs?

Cheers

 

[cyrano]

Transformers?

Piezo discs need a very high impedance. Say 10 Mohms or more. I don't think a transformer would be an ideal solution. A FET input opamp seems much more appropriate.

Or is there something I'm missing?

I use an old Philips measurement amp. It has a 20 Mohms input impedance and that seems to work fine.

 

[staras]

Hey Cyrano,

Hmmm... I thought some high-impedance transformer would work... I do have some contact mics and Radial box with Jensen 12:1 tx and the signal is very usable with it...

Any designs care to share for piezo discs? What's that Phillips amp?


Cheers

 

[cyrano]

That Philips thing is an instrumentation amp. A PM5170. Runs on a 22V battery that is obsolete. But it came with a few of these batteries and they seem to last a looooooong time. It was part of a university lab that was emptied. I fished it out of the bin...

It's DC to 1 MHz, 600 Ohm or 20 Mohm.

The micbuilders group is currently experimenting with contact mics and hydrophones. Take a look:

https://groups.io/g/MicBuilders

 

[staras]

Thanks man! I will check it out. Need some proper gain for the horror box )

 

[frans]

I solved my piezo needs with a preamp from Zeppelin design labs. It is based on a preamp that can be found for DIY on the net, but the package and all makes it easy.
https://zeppelindesignlabs.com/product/cortado-mkiii-contact-microphone/

 

[rock soderstrom]

It is based on a preamp that can be found for DIY on the net

Got link or name for google search? found the schematic