Brian, so that note means that the wire coming of the circuit board labeled Gnd needs to be connected to the back of the guitar pot also? Thanks so much for this I have been looking for piezo preamp that won't break the bank.
Are 1/4W resistors OK?
Yes, I didn't connect it for clarity. When used in a guitar, ALL ground connections should be anchored to the back of the pot. 1/4 &1/2W resistors will work fine. Also if U can't find a 10M resistor, a 2.2 Mor 4.7M will also work fine. this was circuit was given to me by one of the Deads' guitar tech's,who was my "tech mentor" way back in the 80's.this circuit has been around for quite some time(late 70's).thnx for givin' it a look ;)
Radio Shack does not seem to carry the MPF102 any more. Ebay and Jameco have them. Just in case anyone besides me it dying to build this.
Weird? they still carry em' in california? Radio Shack has gone thru some changes in their electronic components within the last few years, I'm not surprised. Mouser is another supplier, they are fast & very reliable.also, any JFet with the same pinout will work.
I am new to the DIY pre-amps builds and have a few "knob" questions. The two potentiometers are both labeled, but I need a little clarity on their purpose. What does the one labeled Guitar actually do? I am looking at the schematic and it seems redundant--to me. Couldn't it be removed and the Stereo Jack and Piezo wire be soldered to the PrmpVol POT? The other one looks like it is labeled a short-hard version of Pre-Amp Volume. Yes? Last question, is there a simple solution to add Tone pot?
I love the way you added the Stereo Jack to act as an On/Off power switch, beautiful!
I have built a semi-hollow u-bass clone from scratch. It uses two 20mm piezos and a ebay bought pre-amp. For the second version of my semi-hollow uke bass, I want to get rid of the vendor bought preamp and build a simple JFET pre-amp that you have posted. Anyway, I am new to DIY pre-amps and would appreciate any insights.
This threads a bit old but I will chime in and say the classic Tillman preamp is one of the simplest to build it you just want a preamp - no pots or knobs. I've built several on perf board --- I'm going to build printed circuit board soon.