Bypass with no power?

[cahannon]

I built a neutron and if I hook up the guitar cord output & input without hooking up a power supply, then turn on my amp I can still play guitar, and hear it through the amp.  This shouldn't be possible right!? The circuit should need power to work. Can anyone explain why I'm wrong?

[smoguzbenjamin]

if it's on bypass it should work. The whole point of true bypass is that it's mechanical, not electronic

[cahannon]

Yes but this isn't a true bypass

[petemoore]

The sound [signal] has found 'another' path?

[lightningfingers]

What kind of bypass is it? If it's a FET switcher, then no that should'nt be possible, but if its an SPDT bypass (a tone sucker) then that'll work with no power.

[cahannon]

Its a dpdt

[Hal]

a dpdt and not true bypass?  

is it "millenium" bypass, or one of those circuits?  Those are still true bypass, they just use leakage from the circuit to switch an led...

[smoguzbenjamin]

From what you've told us I think that it's a true bypass It doesn't do the effect without power, right?

[Benny]

This is the Neutron schematic from GEO, right?  This does use a DPDT but it is not a true bypass.  A true bypass would completely disconnect the guitar input from the circuit while in bypass mode and route it directly to the output.  This schematic takes the "bypass" signal from the output of the first op-amp stage.  However, even with no power applied to the circuit, there is still a path from the input to the output through passive components; this is probably what you are hearing.  The signal is passing through the "gain" pot, R1 and C1 in series, and R3 and C3 in parallel.  So it makes sense that you would hear the bypass signal with no power applied, though it probably sounds "different" than with power applied.

Benny

[R.G.]

This is the Neutron schematic from GEO, right? This does use a DPDT but it is not a true bypass.

Benny is correct. For originality reasons, the schematic of the Neutron is *exactly* the same as the schematic of the Mutron filter it's based on. The Mutron is not true bypass, neither is the Neutron.

This shouldn't be possible right!? The circuit should need power to work. Can anyone explain why I'm wrong?

The "other path" theory is correct.