Univibed Phase 90 from Torchy? Or suggest cap values?

[moogatroid2000]

I am wanting to 'univibe' a phase 90 but after searching high and low here I can only find some mention that a layout was around and may be gone now. I don;t really need the layout so much as the cap values used.
Does anyone have his layout or can suggest the values used to get the univibe mod happening?
I have the trem mod and a couple of other cool mods figured out but the math on this one I just don't follow at all...  :oops:

[blacksnake]

Hi,

Could you give the trem mod and the other mods please ?

Tks

[bwanasonic]

I think you may find the Phase 45 is actually more *univibey* than the P90 with the so-called Uni-vibe cap values. I modded a DOD 201 which is near identical twin to the P45. Don't quote me on the exact values, as I don't have them handy, but I do remember they are pairs a factor of ten apart ( i.e. 10n and 100n).

Ahh, here's the link! :

http://www.diystompboxes.com/sboxforum/viewtopic.php?t=1526

Kerry M

[spudulike]

This is the bit from torchys layout (from the layouts zip file) ... i think this is the part you wanted ...

[puretube]

sorry, but that R27 is wired incorrectly...

[spudulike]

sorry, but that R27 is wired incorrectly...

There are actually two ways to do popless capacitor switching, and I only add this one for completeness. If you have two capacitors in parallel and open/close one of them, you get popping because the open cap leaks down a bit when it's open. The solution in this case is our old friend, the pulldown resistor. Only, used this way, it's more of a pull sideways resistor.

The way you do this is to call one of the caps the primary cap; this one is always in the circuit. In parallel with the primary cap is the secondary cap in series with a 1M or so resistor. The switch "shorts out" the 1M resistor, and when it does, the total capacitance becomes the parallel capacitance of the primary and secondary caps.

Actually, you can put 1Ms in series with *both* caps and alternately short one or the other 1M resistor; this is the same as a selector switch to select one or the other cap, but without the popping. Generally, one cap is left as a "primary" cap, because this saves one throw on the switch. This also works with rotary switches. But then the series string of caps does too if you just hook a rotary up to each node of a string of caps and get fancy about setting up the cap values in series.

http://www.diystompboxes.com/sboxforum/viewtopic.php?t=32370&highlight=capacitor+popping+phase

[puretube]

sorry, but in this case, the switch is wired incorrectly...

[spudulike]

Gotcha - thats straight off the layout I had saved. I thought you meant the resistor shold go to gnd. Ive edited it to show the switching properly. The physical pole diagram is ok though ? And the values calculate ok to me.

[puretube]

the drawing in the middle, 5 posts back, is wrong (and does not do what R.G. described...)

[spudulike]

OK, tell us how it should be wired, and then you can mail/pm trorchy and tell him.

Ive built this according to the layout and it works, no popping. Im sure other people have built it as well.

[puretube]

like R.G. wrote, quote:

In parallel with the primary cap is the secondary cap in series with a 1M or so resistor. The switch "shorts out" the 1M resistor, and when it does, the total capacitance becomes the parallel capacitance of the primary and secondary caps.

the important part in italics...

NOT: "the switch parallells the series-combo of C8/R27 to C9"

[edit]: sorry - no chance of running my scanner/paint pic/upload right now....

[spudulike]

:?:

[puretube]

that`s it!  

[spudulike]

 ta :wink: