Don't forget to Solder all Ground Connections to Back of Guitar Pot

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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.

Jillian

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.

Best Regards,

Eddie U.

Let me clear things up and clarify this is an onboard project wich means its built into the guitars cavity with the other components. The "Guitar" is the CBG's Volume pot. The reason the preamp volume is different is because it controls the amount of boost/gain that is available from the preamp. This project is merely to boost signal, you can simply adjust your amp and/or guitars' tone pot for tone variance.

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.

http://www.till.com/articles/GuitarPreamp/

Old thread. I'm a noob with electronics. After joining this site I have learned to diy piezo and diy pickup stuff. But I now wanna play my cbgs thru a computer. Hence I need a pre amp of some kind. The last post in this thread before this one points to the tillman schematic. But apparently the fet is hard to get now. My questions are twofold. Can I get the fet tillman used in Australia? Secondly. Can you do point to point wiring and leave out a pcb board with any pre amp.If so could someone show in schematic how to do Tillman that way or the schematic at the top of this thread


Hope someone can help me. Cheers. Jonno
Well I've got all the parts now to make this. But I havent a clue about the connections that get made on the board. Anybody home!
Hi Jonno,

You seem to be overthinking it - the black lines in the drawing represent the electrical connections you need to make. You can do this in several ways - either by using the component wires (component legs) pushed through the perfboard and bent to make a connection you then solder to make it permanent, or you can solder a wire between component legs, or you can run a track of solder to make the connection.
You push all components from the same side and do the soldering on the other side.
Perfboard comes in different types - plain (so just holes in the board), with solder around the holes so soldering is easier, or with parallel tracks of copper wiring which can be cut to isolate part of the track or used to make some of the pathway of connections you need.
What type of perfboard do you have?

There are some videos on YouTube (just search "soldering perfboard"). Capacitors easily overheat making a point to point circuit tricky to make and the circuit without the backbone of a perfboard would easily bend causing numerous short circuits.

If you google "Tillman preamp" and click onto the images option you will see the Tillman preamp as a circuit diagram, the one above and one on perfboard with the parallel copper strips. These might help you get more of a feel for the circuit.

I am in the UK so about to turn in for the night. If you need to ask further questions I will check tomorrow and try and answer them if nobody else has already done so.

Regards,
David
Hi David thanx for response. I got parts for the pre amp using the mpf102 fet as I couldnt get j201 used in Tillman. I showed guy at store the pic at the head of this thread and he gave me board with copper surrounding the holes.Called it proto board or something.As far as capacitors go I couldnt work out from this thread which type to get so I just got the little green ones which are polyester. Are they ok or do I need electrolytic ones that are mentioned for Tillman pre amp?

Cheers. Jonno

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