Blue Box problems

[col]

I have been struggling for a while with this which I built from the schematic on Tonepad.com on my own stripboard layout. It is a case of nearly but not quite and I have used the Help function to try and trace the prblems I'm having. I am happy that most of the voltages are consistent with what other people have put up here apart from on two of the transistors , Q2 and Q3 which are as follows;

Q2: C 0.03, B 0.16, E 0,  Q3: C 0.03, B 0.26, E 0

What is happening here as other people have noted the collectors as the lovest reading, but not as low as mine! The resistor values are all correct and I have checked with the multimeter as well as the colours on them.

When I have the blend pot at one end it sounds almost right, at the other end it doesn't matter where I hit any string the note produced is exactly the same. I have checked all nodes, resistor values, cap values etc. and used 2N3904s as suggested. I have used a lin pot instead of a log pot but I don't think that'd make much difference. Any suggestions would be greatly appreciated.

Col

[George Giblet]

With that circuit you only make judgements that something is wrong if the voltages were radically different.  I suspect your voltages are OK. 

You really need to drive a sine-wave into the unit and look at the signals with an oscilloscope.   For example if you put in a 500Hz sinewave you check that the frequency was getting divided down.  You can work out what was going on by ear (make sure your amp is tuned down and the sine level is relatively low).   You could vary the frequency to confirm the outputs are tracking.

If you got the diodes or caps around the wrong way it might do something weird.

[col]

Traced it. One of the caps was the wrong way round. Once reversed it works OK but I think I will try some of the other caps it says to leave off as it sometimes goes unstable on high notes. Tracking is perfect. If you hit a note and let it decay it gives some very wierd synth like sounds and is totally unpredictable. Fantastic! I might swap the lin pot for a log as soon as I can get hold of one.