Mk103 doesn´t like power from a wallwart?

Kits Mini Kits Range
1

Hello,

I made some minor modifications to the circuit.

I use a 6,3 mm Jack instead of the microfon and I leave R1 out. (I think this was powering the mic). So I can use the kit with an electric guitar or a mixer. It works well with different levels. I also changed one of the LED´s to the LED-Part of an optocoupler. Powered by battery everything works as it should.
But if I use a wallwart it´s behaving strange. The Led´s are full on with no signal when level pot is halfway. With battery they never lid without signal. I tried different wallwarts, switching types and conventionell. I tried some filters I made from inductors and capacitors. The batteries have been from 8V to 9.9V, the wallwarts from 9.6V to 12V.
Does anybody know what´s going on, or even know how I get this up and running with a wallwart.

Thanks

Stefan

2

Ripple and noise from an AC adaptor trigger this very sensitive circuit.
You might want to try a regulated adaptor, it might help.
Do not use a switch-mode adaptor.

3

Hi,

thank you. I tried with a regulated supply. I tried some lowpass-filtering, that helps a lot with audio circuits, but not with this one. I will try some more filtering. Any other ideas?

Stefan

4

Yeah, stick to batteries. Consumption is very low.