Another Theremin Circuit

I am trying to build the following:

Another Theremin Circuit - Added by: omhoge 6/12/2011

I can't find values for C6 or R22.  Also, any suggestions for substitute for Q3,5,7 - PN3640?

And I cant find the schematic on the link you provided.

Fred.

Here's the link to the schematic :

http://www.thereminworld.com/pics/schematics/AnotherThereminCircuit.jpg

Wow, 20MHz!  This is the highest frequency Theremin circuit I've ever seen.

C6 = 4.7pF

I might be blind, but I don't see R22 on the schematic.

Probably most general purpose small signal transistors would work here: 2N3904, 2N3906, 2N2907, etc.

I cannot find R22, C6 is shown as 4.7pF

Why are you choosing this schematic? Unless you are really sure about electronics (both theory and practice) and can fully explain the circuit (which I dont think you can - if you could, you would see that there are dozens of transistors you could use to replace the PNP's you cant source) I think you are making a big mistake going for this one!

Pick something tried and tested, something where you can buy the variable and fixed inductors you need and not have to wind your own, and something where there are people here who are familiar with the circuit and can help you when (not if!) you have problems getting it to work.

I advise the EM theremin, or one of the Silicon Chip kits.

Alas, I cannot help any more - And if you go for this circuit without giving a damn good reason for your choice, I wont be offering any more advice than this: Without spending time analysing the circuit fully I cannot confidently recomend replacement transistors - but there is nothing special that I can quickly see, so BC212  would probably be fine, or the BC556BG which has max Vce @65V, Hfe @ 180 and IC @ 100mA.

Hi Dewster! - Ya just beat me, LOL ;-)

We should have an online pub here at TW, where we can go for a drink and a chat! ;-)

Fred.

Correct link to schematic =  http://www.thereminworld.com/pics/schematics/AnotherThereminCircuit.jpg

Wrong link = http://www.thereminworld.com/Forums/pics/schematics/AnotherThereminCircuit.jpg

"We should have an online pub here at TW, where we can go for a drink and a chat! ;-)" - FredM

Fred, you are one of the most interesting people to technically chat with I've ever encountered.  If we had a TW online pub I'd never get anything done! (As opposed to rarely getting anything done sans e-pub.)

Thanks for the advise. I reviewed the EM Theremin project and have only 1 concern.  I can find absolutely no information on U3 - LM13600N. Any suggestions on a suitable Op Amp?  Being new, I've never heard of one being described as a "transcendance" amplifier.

http://electronics.mcmelectronics.com/?N=&Ntt=lm13600&x=20&y=9

It's not a normal op amp. Its used as a VCA in the EM theremin, which is basically a Moog EW standard.

http://www.komponenten.es.aau.dk/fileadmin/komponenten/Data_Sheet/Linear/LM13600.pdf

Data sheet.

This came up first from a Google search. I'm sure there are many others.