Figuring out if a circuit is reverse polarity?

[ISuckAtPedals]

Yesterday i put my fuzz pedal and my mxr distortion in one pedal box using the same power source and a blend knob between the two. They run together fine, fuzz runs fine alone but sounds "out of phase?" But if i turn the fuzz off and leave the Distortion on i get a loud squeal which changes in tone as i move the distortion volume or the blend knob between the pedals.

Did i wire a reverse polarity pedal with a normal polarity pedal? heres the two boards.

[GGBB]

I believe the outputs of the two pedals are out of phase with each other - if that's what you are asking. That alone shouldn't cause the squeal problem however - that's probably a build issue - you haven't shown how you've wired the whole thing - switches, jacks etc.

[amz-fx]

You know...  that layout for the Dist+ doesn't seem to have a Ground connection.

It is the third horizontal row from the top, and should be connected to the power supply ground (negative).

regards, Jack

[R.G.]

Somewhat related info:

Way back when fuzz was new and dinosaurs roamed the eartn, pedals would sometimes be intentionally designed to subtract the original signal to emphasize the distortion. I have a recollection of a build-it article that stated exactly that.

To determine inverting or not, you count the number of inverting stages. If it's even, the overall combination is non-inverting. If it's odd, the overall combination is inverting.

For bipolar transistors, the most usual two stages are the common emitter (CE) and common collector, or emitter follower. The CE stage is inverting. The follower - well, it follows so it's non-inverting. Things get funny if signal is taken from both collector (as in CE) and emitter of a transistor, and you have to hunt and peck through what follows the transistor to figure out which one is predominant. If there is a full-bypass to ground cap on the emitter and signal is out of the collector, it's inverting.

For FETs, it's much like the above. The drain output is inverting, the source is non-inverting compared to signal at the base.

Both bipolar and FET stages, you CAN insert signal at the emitter or source, and the drain signal is then non-inverting.

For opamp circuits, you can look at whether signal is applied to the (+) input or the (-) input. If it goes into the (-) input through a resistor, it's inverting. If it goes into the (+) input, it's non-inverting.

This in general only applies to the mid-band frequencies, the frequencies where you're not close to some high end or low end roll off of volume. Every series capacitor in the signal chain causes a limitation of low frequencies by the rule of F = 1/(2*pi*R*C) where F is the frequency of half of the ultimate phase shift (where the cap causes 45 degrees of shift; it's 90 degrees maximum ) C is the capacitance and R is the impedance of the stage after the cap plus the source impedance of the stage driving the cap. So each series cap can rack up as much as 90 degrees of phase shift. And the rolloff points may be in the middle of the audio range, so it's tough to figure out if a string of stages is inverting or not without examining them all to see if they have inter-stage caps and at what frequency these cause phase shift.

I threw in that last, confusing paragraph just to say, you MIGHT get the inverting/non-inverting right by counting inverting stages, and most often you will, but sometimes there's a filtering phase shift hiding in there. Deliberate tone filtering can really change phase a lot.