Univox - Univibe (Uni-vibe)  [schematic]

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Univox - Univibe (Uni-vibe)  [schematic]

Postby analogguru » 24 Oct 2007, 10:46

Here are some hires-guts:

http://cgi.ebay.com/Univox-Uni-Vibe-ori ... dZViewItem

and another one:

http://cgi.ebay.com/VINTAGE-UNI-VIBE-UN ... dZViewItem

Interesting the 470pF ceramic cap for the phase stage in the lower middle of the pcb.

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Re: Univox - Univibe (Uni-vibe)

Postby lolbou » 22 Aug 2009, 21:42

BUMP!

Bumping the thread for the upload of Univibe track side/component side pics... Cheers!

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Re: Univox - Univibe (Uni-vibe)

Postby pf_fan » 22 Aug 2009, 21:59

There you go!
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Re: Univox - Univibe (Uni-vibe)

Postby lolbou » 22 Aug 2009, 22:05

Awesome, really, cheers! :applause: :applause: :applause: :hug:
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Re: Univox - Univibe (Uni-vibe)

Postby pf_fan » 22 Aug 2009, 22:10

No problem, I found this somewhere, but really don't know where ;)
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Re: Univox - Univibe (Uni-vibe)

Postby lolbou » 24 Aug 2009, 19:48

On the original schematic, the speed pot is a 250k rev. log. But on RG's and others I found, it's a dual 100k...

:scratch:

What's wrong with it? This must change the lowest frequency? What's the value found in the stock pedal?
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Re: Univox - Univibe (Uni-vibe)

Postby pf_fan » 24 Aug 2009, 22:00

lolbou wrote:On the original schematic, the speed pot is a 250k rev. log. But on RG's and others I found, it's a dual 100k...

The original had a dual pot inside the pedal. At least that's what I've seen. I attached one of the pics from my personal archive :)
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Re: Univox - Univibe (Uni-vibe)

Postby lolbou » 24 Aug 2009, 22:13

Yeah, a dual one, I know (I have an other pic too... :wink: ). But the value remains unknown... :hmmm:
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Re: Univox - Univibe (Uni-vibe)

Postby R.G. » 25 Aug 2009, 03:10

There's really very little mystery left in the Univibe. I've measured both 250K and 100K pots in original univibes given to me to repair. Both work.

The originals are actually dual log pots, turned into reverse log by the direction the shaft is turned mechanically, I believe. I haven't seen a real univibe footpedal in a long time, but that's what I remember. You want reverse log for this, just like any phase shift oscillator to make the change in frequency per pot rotation seem even, not bunched on one end or the other.

The originals have both series and parallel resistors to the pot to limit what the pot does electronically. So the pot value is not hyper-critical. Small bear stocks a dual 100K reverse log pot that will go into a crybaby enclosure and do the trick. My PCB layout for a vibe clone predates the world wide web, and is from a time when the only communications medium was usenet posting. It's been updated several times for better fit, easier soldering, etc. The current Neovibe board can be mounted inside a crybaby pedal. Several people have done that. I have a new layout I haven't released yet that is designed to fit the mounting bosses for a crybaby deliberately. This version includes a tremolo (like the 'vibe's precursor, the RT-18... that's Resly-Tone...) and a single pot driving a dual Led/LDR for the speed control to get rid of that pesky dual reverse log pot.

The most common problem with vintage vibes is burnout of the lamp driver.

I got a raft of equine solid waste material when I released what was to become the Neovibe. The entire Neovibe is a part-for-part repro of the Univibe, but I ditched the R-C filtering for a three terminal regulator. There were some Very Offended People who held the opinion that the repro could not sound anything like the original because it now had clean DC to the audio path. Silly, I know, but the internet was even less civil back then.

The Neovibe has satisfied hundreds? Thousands? of people over the more-than-a-decade that it's been available. The ones who haven't been satisfied have mucked up the build. All of those I found out about I got running.

It ain't magic. It's a collection of parts.
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Re: Univox - Univibe (Uni-vibe)

Postby lolbou » 25 Aug 2009, 08:08

Thanks RG, your articles on this unit are my very Bible at the moment (and your optocoupler mod helped me a lot on a modern Vibe repair...)!

R.G. wrote:I've measured both 250K and 100K pots in original univibes given to me to repair. Both work.


So that's why I've found both online...


R.G. wrote:The originals have both series and parallel resistors to the pot to limit what the pot does electronically. So the pot value is not hyper-critical.


Well, it's because I computed the equivalent resistance of the 4k7+100k//220k and 4k7+250k//220k and I almost found a 50k difference in the values, so I thought it would affect the LFO frequency... Still I don't really catch how the resistors can limit both ends of the pot course (especially the lower)... :scratch:

R.G. wrote:The Neovibe has satisfied hundreds? Thousands? of people over the more-than-a-decade that it's been available. The ones who haven't been satisfied have mucked up the build. All of those I found out about I got running.


I'll give it a closer look!!

Thanks a lot for your answer RG...
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Re: Univox - Univibe (Uni-vibe)

Postby lolbou » 25 Aug 2009, 11:09

The LFO went on breadboard this morning (with BC548s)

When pot is shorted: f= 5Hz.

When pot is 100k: f= 0.76Hz
When pot is 240k: f= 0.35Hz (I used fixed resistors)

So the value of the pot does affect the frequency (in this I'm right), but the sweeping cycle is 1.5s longer with 240k, which is not probably critical at extreme values like RG said...

By going for a 100k, you might get happy with it though...

Just my two cents (as regards to RG's billions :wink: ) here...
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Re: Univox - Univibe (Uni-vibe)

Postby UZILSD » 25 Aug 2009, 20:29

R.G. wrote:
The Neovibe has satisfied hundreds? Thousands? of people over the more-than-a-decade that it's been available.


I've built 2 of 'em, one for me and one for a friend of mine and we are more than satisfied, we are happy!!! :D

Your "The technology of..." articles are milestones for DIYers.

With your optocoupler LFO mod now I'm building a potless pedal control for the vibe with an hall proximity sensor. I'll post results of my experiments when the thing will been tested properly.
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Re: Univox - Univibe (Uni-vibe)

Postby yeeshkul » 01 Sep 2009, 07:00

so am i, no doubt that thing works great! :)
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Re: Univox - Univibe (Uni-vibe)

Postby Kregg » 14 Jan 2010, 16:13

I'm am assembling a Neovobe build and I need some guidance on how to do the following (from GGG project file https://www.generalguitargadgets.com/pd ... update.pdf ):"If you want the best performance out of your Neovibe, leave these two resistors out and use a 200K pot to adjust the mix for deepest phasing. Then measure the resistance on each side of the wiper and put the nearest 1% resistor values in for R35 and 36."

Could someone please offer a clearer explanation to someone in their rookie year?
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Re: Univox - Univibe (Uni-vibe)

Postby rackham » 14 Jan 2010, 18:50

The two resistors form a divider.

This is the same principle as the volume control pot used on pretty much all pedals.

So, to replace those two resistors with a pot, you'd attach the middle pin of the pot at the point where R35 and 36 meet, with pin 1 joining C18 and pin 3 connecting to R37. Or vice versa, the important one is having pin 2 at the junction of R25 and R36.

Then turn the pot until you get the sound that you like the best. Un-solder the connections (taking care that you don't nudge the pot shaft in the process) and measure resistance between pin1 and pin2. Then measure the resistance between pin2 and pin3. These 2 readings give you the values for your ideal R35 and R36.

Hope that helps/makes sense?
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Re: Univox - Univibe (Uni-vibe)

Postby Kregg » 15 Jan 2010, 00:38

Excellent explanation, thank you very much!
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Re: Univox - Univibe (Uni-vibe)

Postby goonierat » 19 Aug 2010, 15:40

On this topic of the 200k pot refinement method - can I ask: why not just leave the pot there if it allows tweaking?

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Re: Univox - Univibe (Uni-vibe)

Postby coi2001 » 07 Nov 2010, 16:09

I built the forum vibe using Brad's board form Classic Amplification. Got the reverse dual audio pot, LDRs, and lamp from Small Bear and used a cough syrup dosing plastic glass lined with aluminum foil as light shield. Works great. I appreciate the usefulness of the trimpots which protect the lamp from blowing (although I managed to fry one) and allow you to dial in what sounds best to your ears. I have not made a power supply for it, and I am running it on 2 x 9V batteries (used, providing 15-16 V).

i was wondering what people do for power supplies for univibe-type projects. Has anyone tried running it on 9V power supply and using a voltage doubler and a 15 V regulator?
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Re: Univox - Univibe (Uni-vibe)

Postby mictester » 07 Nov 2010, 16:56

coi2001 wrote:I was wondering what people do for power supplies for univibe-type projects. Has anyone tried running it on 9V power supply and using a voltage doubler and a 15 V regulator?


That's a really nice build!

Power for it - I always mains power them, using a 15 VA 15V AC secondary transformer, a little 5A bridge rectifier, 2200µF 35V smoothing capacitor, 7815 regulator with 100nF bypass capacitors at the pins (on both input and output) and a 1000µF 25V supply filter capacitor.

You could use a voltage multiplier, but the little 7660S and so on would not really be powerful enough to drive this current-hungry pedal. You'd have to use something more sophisticated.
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Re: Univox - Univibe (Uni-vibe)

Postby coi2001 » 07 Nov 2010, 18:42

mictester wrote:
coi2001 wrote:I was wondering what people do for power supplies for univibe-type projects. Has anyone tried running it on 9V power supply and using a voltage doubler and a 15 V regulator?


That's a really nice build!

Power for it - I always mains power them, using a 15 VA 15V AC secondary transformer, a little 5A bridge rectifier, 2200µF 35V smoothing capacitor, 7815 regulator with 100nF bypass capacitors at the pins (on both input and output) and a 1000µF 25V supply filter capacitor.

You could use a voltage multiplier, but the little 7660S and so on would not really be powerful enough to drive this current-hungry pedal. You'd have to use something more sophisticated.



Thank you, the power consumption of my build if 24-31 mA, depending on the speed-intensity setting, but I see you point of not messing with the voltage doubler and going for a little power supply. It's just that it's another box/adapter to carry.
Do you usually use a wall wart type of transformer and the rectification/power conditioning in the vibe box?
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PS: Attached below are photos of the light shield before I painted it black. It's held on the board by three pin connectors that wedge into the inside of the plastic cup lip and keep it firmly in place.
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