Question about R.G.'s Polarity Reverser

[ianmgull]

Hello,

Sorry if this has been covered before but I can't find an answer.


Does anyone know what the resistor value's are supposed to be for this:

http://geofex.com/Article_Folders/polarity_reverser/polarity_reverser.htm

I'm building a parallel distortion box:

http://www.diystompboxes.com/smfforum/index.php?topic=67435.0

And I plan on putting the buffer on the same board as the Polarity Reverser.

Thanks!

Ian

[Pushtone]

I think you PM'd me about this. Sorry I didn't get a chance to answer

I want to know the same thing.
I have the circuit on the bread board right now with a buffer in front of it.

I'm getting a slight drop in level when the switch is closed.
I've tried a lot of values but I can not get unity in both states of the switch.

I lost some interest in getting my parallel effects mixer project done.
This is a good time for a thread. May get me back into it.

Need sleep now. tomorrow I will go over the values I'm using on the bread board.

[kvb]

The ROG spliter-blend has an extra buffer and uses 220K for the other resistors.
R.G. told someone - in a post, who knows where - that 10K can be used for the other resistors.

I breadboarded the circuit and used both values - without an extra buffer - and things seemed to work just fine.
I double check for the polarity change by mixing two signals together and listening for a cancelation.

[kvb]

Also, if you are just trying to maintain polarity between different circuits - that are permanently configured - you do not need the polarity reversal circuit. Any single transistor stage can be either an inverter or a non inverting buffer. You just need to keep track of how many inversions there are in each circuit. An inverter at the end of a certain circuit - depending on the values used - might not change its sound much and may give you other options like additional tone shaping without volume loss.

[dschwartz]

totally agree..you don´t need the polarity reverser..just an inverting gain or buffer stage..

[ianmgull]

Thanks for the info guys.

I know personally I am blending five signals: 2 Tube Screamers, a Big Muff, an Uglyface, and the clean signal. You don't think I'd need to worry about phase cancellation?


thanks again.

ian

[dschwartz]

check in each one of those circuits if the output is out of phase.....if one of them is inverted, then use a phase inverter (I.E. fet or transistor gain stage with gain= 1)

[Pushtone]

I think Daniel means that it is not unnecessary when the circuits you are parallel mixing are permanently configured.
Just build them with a non-inversion output.

You absolutely do need the polarity reverse if the idea is like JD Sleeps PARALIZER where any circuit can be connected to a loop.

Dave

[ianmgull]

dschwartz: Thanks, I'm still in the middle of a 450 page electronics theory book but I've not gotten far enough yet to be able to tell if the circuit is out of phase yet.

Pushtone: Conceptually my box will be like JD's Parallelizer, except it will all be in one box, with the 5 channels I listed above. I'm sorry but I think I misunderstood you, it is "not unnecessary". So you would recommend I do put the inversion circuit in there?

Thanks for the help.

Ian

[dschwartz]

ian:
is not that hard..look:
- if the output of a transistor or fet stage comes from the drain (or the collector), the stage is inverting (typically gain stages)
- if the signal in an opamp goes into the - input, the stage is inverting.. (some gain stages)

- if the output of a transistor or fet stage comes from the source (or the emmiter), the stage is non-inverting (typically buffers)
- if the signal in an opamp goes into the + input, the stage is non-inverting.. (some gain stages, and buffers)

now, follow the signal through each stage of the pedals, checking the polarity of each output..

do it like this:
for each stage asign number 1 if non inverting and -1 if inverting, for example , a signal chain:

inverting--> non-inverting-->inverting----> inverting
is:
-1 ---> 1 ----> -1 ---> -1

then multiply the numbers:

= -1*1*-1*-1= -1...then the entire chain is inverting

as a rule, if the chain has an odd number of inverting stages, the output will be inverted..

then..you have to invert the signal again on those pedals having inverted outputs..

[ianmgull]

Wow, thanks for the help Daniel. That's exactly what I needed to know. So it looks like I wont need to worry about inverting the signal in my box. Thanks!!!!!!!!!

ian