[sdiy] Kraakdoos output revisited

[The Peasant]

Well, I had another go at it today. The problem with the box that was not loud 
enough was that I had reversed the power and ground connections on the 
transistor amp section. I am quite surprised that it functioned at all this 
way, and that the transistors did not immediately fail. As soon as I corrected 
the wiring, it functioned just fine, nice and loud even with the 12 ohm 
speaker. I paralleled a 8ohm-10K transformer across the speaker for a line out, 
and it did not appear to affect the sound significantly at all. What comes out 
of the other end of the transformer may be a different case, however.

Then I attacked the non-working unit, and found the problem to be excess solder 
flux on the contact pad connections absorbing moisture from my fingers and 
shorting out. When I tried to measure for leakage, with my fingers removed of 
course, the moisture evaporated and no leakage was found. However, if I exhaled 
some moisture laden breath onto the contacts, the sound would change 
dramatically. A bit of flux remover and scrubbing appears to have solved that 
problem.

So both of my weird problems were, as usual, caused by myself. Nothing new 
here, move along, move along....

Take care,
Doug
______________________
The Electronic Peasant

www.electronicpeasant.com