I’m looking for a circuit to boost a piezo mic up to synth-ish level. Specifically a circuit that runs on a single supply (9v). Minimal components—don’t need any tone control, etc
That disqualifies a lot of the circuits out there like the mikrophonie.
I see some options with jfets which would be fine. Or LM386?
I should also note I’m not worried about getting “good” sound from it. Lo-fi is totally fine
Just throwing it out in the hive mind see if anybody has a go-to circuit for this
I tried this one and it didn’t work for me
I want to try this one but I can’t find any spare Jfets around, ordered some to play with
Some discussion here and links to a couple circuits, haven’t tried them:
Take care with your JFET selection - I found out the hard way that ones meant for switching/chopper applications are terribly nonlinear - you want to make sure you get small signal amplifier ones.
That’s an audio amplifier designed to drive a speaker, not a high-impedance input. What do you plan to connect this to?
Would using two 9 V batteries be ok?
Power will be from a 9v dc wall wart as part of the relay mixer build I’m working on. It will be plugged into a vca/mixer like any other audio/noise source
I guess I could redesign for an 18v wall wart and get ±9? Maybe not…
Or run the +9 thru a inverter ic
amazingly enough the safety valve acts as a pretty good piezo amplifier! (I seem to remember seeing one in your setup)
ooh also! 9v the safety valve thingy without the opamp haha, any excuse for a superficial valve sticking out the top 
I tried a Similar Design to the one on the top and it works. Just has noise issues so you need to have the wires as short as they can be. I remember reading somewhere that it isn’t a ideal design. I have been looking into pre-amping my Piezo in a toy piano too. I’ll post what I find. Looking again into this this one looks pretty promising Piezo preamp So I am going to give it a go.
I’ve used the tillman preamp before, playing with R2 value for more/less gain:
http://www.till.com/articles/GuitarPreamp/
Schematic looks insanley close to the one you’ve already tried though. 
It’s a bit different, and the next one I’d try but I can’t find any damn jfets!
ebay…dfx parts
Got any junk electret microphones, I put some under the knife to make a piezo amp and it works great… I think I changed one resistor to drop the ampage across the FET I’d have to check though
