How can I make my Phase 90 go a little slower?

[msb69]

I have one of the MXR Custom Shop Script Logo Phase 90 pedals -- not the '74 hand wired one.  I would love to make the minimum speed on the pedal a little slower.  Will a higher value pot do the trick?

[GtrmanMoe]

Ease off the throttle a little?

JK.....I couldn't resist

[Rodgre]

This is a great question.

I find that I often wish that I could get phasors and other LFO-modulated circuits to go slower.

Roger

[frequencycentral]

Just add another 0.01uf cap in parallel with the 0.01 that's already there. Make it switchable, for slow/fast. Should work.

http://www.geofex.com/FX_images/p180.gif

http://www.tonepad.com/getFile.asp?id=42

[Mark Hammer]

And what of the cap to ground labelled 10uf in some drawings and 15uf in others?  Does that simply provide appropriate smoothing of the waveform produced by the LFO?

[frequencycentral]

And what of the cap to ground labelled 10uf in some drawings and 15uf in others?  Does that simply provide appropriate smoothing of the waveform produced by the LFO?

Oh! Is that the timing cap? I assumed the 0.01 was. Sorry!

[Ssmit]

And what of the cap to ground labelled 10uf in some drawings and 15uf in others?  Does that simply provide appropriate smoothing of the waveform produced by the LFO?

Oh! Is that the timing cap? I assumed the 0.01 was. Sorry!

So are you saying to put a cap of the same value in parallel with the existing cap?

[Mark Hammer]

And what of the cap to ground labelled 10uf in some drawings and 15uf in others?  Does that simply provide appropriate smoothing of the waveform produced by the LFO?

Oh! Is that the timing cap? I assumed the 0.01 was. Sorry!

No.  I'm not telling your you're wrong.  I just never understood the LFO in the P90 very well, and wasn't sure of the role of that particular cap.  It certainly looks conspicuous.  I just don't know what it does.

[petemoore]

  So jump across it with another capacitor, see how the LFO responds, that or parallel/insert one for reduced value...whatever is most easily fascilitated...to see which way will index the speed control to a lower speed range.
  Not that I understand it either, fiddling with those two values will reveal a speed change [?].

[frequencycentral]

So are you saying to put a cap of the same value in parallel with the existing cap?

And what of the cap to ground labelled 10uf in some drawings and 15uf in others?  Does that simply provide appropriate smoothing of the waveform produced by the LFO?

Oh! Is that the timing cap? I assumed the 0.01 was. Sorry!

No.  I'm not telling your you're wrong.  I just never understood the LFO in the P90 very well, and wasn't sure of the role of that particular cap.  It certainly looks conspicuous.  I just don't know what it does.

  So jump across it with another capacitor, see how the LFO responds, that or parallel/insert one for reduced value...whatever is most easily fascilitated...to see which way will index the speed control to a lower speed range.
  Not that I understand it either, fiddling with those two values will reveal a speed change [?].

Yes, we are saying put a cap of the same value in parallel with the 0.01 - and see what happens.

If that doesn't reduce the range of the speed, remove it.

Then put a cap of the same value in parallel with the 10uf and see what that does.

If that doesn't work either, try paralleling both the 0.01 and the 10uf with caps of the same value and see what that does.

It would be best if you used crocodile clips to do all this, as that way it's easily reversible.

Please post your results on the thread, as Mark, Pete and I are real curious as to which cap (or combination of caps) will do the trick!

[DougH]

I believe the 15uf sets the speed of the LFO.

[frequencycentral]

I believe the 15uf sets the speed of the LFO.

Doug H is probably right - he just spent ages breadboarding an MXR phaser and ended up with a simply gorgeous looking pedal.

[Dai H.]

should be an old post by gus s. saying that that 15uF does it. I tried and it did. Mine's a 3 opamp one, and I also converted to the older style circuit. The original state had a different appeal but I like it more modded. Just need to figure out how to reduce the (clock?).

[Ice-9]

Doug H is probably right - he just spent ages breadboarding an MXR phaser and ended up with a simply gorgeous looking pedal.

Do you have a link to the Doug H mxr phaser so i can check it out.

Yes I do believe the 10uf cap is the timing cap as well.

[frequencycentral]

Doug H is probably right - he just spent ages breadboarding an MXR phaser and ended up with a simply gorgeous looking pedal.

Do you have a link to the Doug H mxr phaser so i can check it out.

Yes I do believe the 10uf cap is the timing cap as well.

"Pictures!" thread, page 329, it's gorgeous: http://www.diystompboxes.com/smfforum/index.php?topic=36392.6560

[mdaudet]

What if you replace the speed pot with a higher value? like 1M Reverse log (500K - 250K stock). The slower speed is achieved by the maximum value of the pot, ergo, the fastest rate is the pot at no resistance.

Maybe that should work.

I guess the 10uF integrator cap is the for the shape of the wave instead of a speed purpose. (Just thinkin' out loud)

cheers.