Powering a small amp and a pedal with the same power source

[tca]

Hi,
I've just build a small 1W amp called PUNCH and it is great, I've tested it with several pedals in front of it and everything work out well, no problem what so ever. Then I though it would be nice to build my favorite OD circuit, the Tube Sound Overdrive (TSO) by Arsenio Novo, and added this circuit to the amp circuit. I have this pedal in a box and it is powered by a battery and it works with the amp but if I use the same 9V power source to feed both circuits the amp squeezes like a pig!  I've also tested the TSO with the same 9v power source with another amp and the circuit is working as expected. Both circuits work fine independently.

Obviously some oscillation is passing trough the power source and makes all circuit resonate because both circuits interact. The point is that I can not understand why does this happens, it eludes me completely. Can anyone provide me with a plausible answer explaining where/why these oscillations occur?

Thanks.

[Mark Hammer]

1) Is there enough current to go around?  I imagine there is, but the question needs to be asked just to get it out of the way.

2) Are the supply paths for the two things sufficiently isolated from each other?

[tca]

1) Is there enough current to go around?  I imagine there is, but the question needs to be asked just to get it out of the way.

The power source can deliver about 1.5A and it is regulated.

2) Are the supply paths for the two things sufficiently isolated from each other?

That is a good question... both share the same +9 and GND pin.

P.S.
Probably powering the TSO with a resistor (820 R) and a capacitor (10u) to ground will decouple the two circuits...

[tca]

Hi,
just solved the problem. I've used a 300R and a 100u capacitor to ground to power the TSO:

+9V ---////////----------> to TSO
                       |
                     -----
                     -----
                       |
                    -----
                    GND

Mark, your question make me think about it.

Thanks.

[artsinbloodshed]

haha tca, you beat me to it!
kudos for debugging the prob.I'll do it for my combo preamp/lm386 !
thanks man!