PCB design dilemmas

[ElectricDruid]

Really? Those look pretty well separated to me, and they've got ground pour between them too.

Isn't there something else that could be causing the oscillations?

Whenever I think "It must be that causing the problem, because I can't think of anything else it could be" to find a fault, I'm wrong. It's always some other thing that you didn't think of.

HTH,
Tom

[temol]

ElectricDruid -you are probably right.. I've just cut the those tracks next to the potentiometer leg and transistor leg, then connected blind tracks to the ground. And.. stiiiiiiiiiiillll the same probem . So.. who's to blame.. me of course, because it's my pcb design, not very successful as it turns out

T.

[ElectricDruid]

Ok, so what makes you so sure it's the PCB and not a error in the schematic?

Do you have a version on the breadboard that doesn't oscillate that you're sure is the same?

It's very easy to let some difference between the tested version on the breadboard and the recorded version on the schematic creep in. And then when you design a PCB based on the schematic (rather than on what you had on the breadboard) it comes back to bite you and you get problems. Ask me how I know....

Tom

[temol]

Do you have a version on the breadboard that doesn't oscillate that you're sure is the same?

I have already dissasembled the breadbord version but it worked perfectly. Of course there is always some possibility of the mistake, I cannot rule it out. But I have checked the printed schematic against Eagle schematic  couple of times.

Tomek.