On 9/26/2011 12:57 PM, Jacopo Monegato wrote:
>
>
> Any suggestion? I already changed a couple of capacitors in the supply ci=
ruit, but nothing changed. the circuit is:
>
>

what is the source of the 12VDC being supplied to the circuit ? Is it by=20
chance from a switch mode supply  ?  Anytime I hear someone say that=20
changing the power source changes the circuits performance I start with=20
that. Try powering the circuit from a battery vs a power adapter. =20
Sometimes power supplies of switching designs maintain some connection=20
to the wall outlet voltages which would mean you and the local=20
environment are maintaining some connection to the circuit under test.=20
You touch a pin altering the flow of current.  I went through this with=20
a circuit that would perform odd and found that when I put my foot on=20
the floor is when it was behaving odd. Turns out the power supply was=20
very dirty and me placing a foot on the floor was completing the loop.


--=20
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