Help with a simple build

[fldrvr]

I'm having trouble with this simple optotheremin:

http://www.geocities.com/SoHo/Lofts/871 ... remin.html

Colin, other esteemed wizards of this site- I'm looking at you guys.


I'm fairly certain I've got all the connections right- as far as my understanding goes. I used a cap with the # 224 on it, so I'm assuming its .22 uf (then again, I'm retarded at math). Is this too high a capacitance value?

Also, I think that my opto resistor may be too high a value. It came from Radio Shack and there were no values printed on the package, but it is of a fairly large physical size (3 or 4 mm across). Think that's the problem?

Also- I have a number of transistors whose datasheets list them as "General Purpose" and "Switching". Am I correct to assume that those types can be used for this appilication?

I'm finishing up an APC right now. Hopefully I can post some shots of the finished build

Thanks

[caress]

that cap value shouldn't be a problem.  different cap sizes will just give you a different frequency range of the phototheremin.  you should try out some other photoresistors if you have them as you'll get a different sensitivity response.  the problem probably lies in your transistors.  it calls for a 2n3904 (NPN) & 2n3906 (PNP) so you should just go with those for now.  i'm pretty sure you could sub in a different gen purp NPN or PNP but not positive.  just make sure you have the NPN in Q1 and the PNP in Q2.  that's important.  good luck!

[fldrvr]

I did wind up using the transistor specified by the schematic. I also follwed the pinout as shown on the schem, maybe mine have a different pinout, I guess I'll have to check that.

[caress]

download the datasheets for the 3904 & 3906, although i'm pretty sure they have the same pinout.  double check and make sure you have no solder bridges, cold solders and that your grounds and 9v+ are both tied to all the correct points.  also, the photoresistor might be too big or too small, although you should be getting SOME sound even if it's off...