Piezo mic phantom powered preamp with balanced output

[heuermh]

There is enough documentation on this that I should be able to do it myself (and will give it a try)

http://www.zachpoff.com/diy-resources/alex-rice-piezo-preamplifier/

Schematics
http://www.zachpoff.com/site2/wp-content/uploads/preamp-eagle-schematic.png

https://cdn.shopify.com/s/files/1/0698/2265/files/Figure_3_Cortado_Schematic.jpg

The latter one is licensed https://creativecommons.org/licenses/by/4.0/, so any further adaptations will need to be as well.

[Zanius]

I am somewhat interested in piezo pickups myself, so here is one I drawn up really quickly :)
I think it's correct.



***EDIT***
I now see that the 2K res should prob be a trimmer for biasing. Also q1 and q2 should be matched.

[Neil mcNasty]

It's probably a good idea to write down the transistor part-number (J201 in your case), because many will read the schematic/docs and stick the specified 2N3819's in there, and then think something is wrong with their build, when they discover that it does not work (because of wrong pinout)
The pinout for the 2N3819 is DGS, and for the J201 it is DSG
This layout is suitable for J201, but not for 2N3819 (without bending the legs) and this should be specified in order to avoid confusion...

Also:
The 3M resistors are 3.3M in some versions of the schematic, so it should be safe to use 3.3M...
The 2K should be a trimmer...

This layout should be correct if you are using 2N3819:

[heuermh]

Thank you!  The best I could do was 11x13.

I have a bunch of 2N3819s, so I'll give that layout a try first.  For biasing, I'm guessing just go by ear?

[Neil mcNasty]

Biasing by ear works fine in my world, as long as it's only one trimpot...
But when biasing something like a large amp-sim circuit with 4 JFet's with trimmers, then I bring out the DMM to get a good starting point.