Univox - Univibe (Uni-vibe)

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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Redhouse
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Post by Redhouse »

coi2001 wrote:
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?
thanks
Costantino

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.
Your build looks great, you do good work.

The vibe doesn't need much current to run (depending on your bulb) I always suggest a 22-24VDC/200mA going into your box, and stepping it down with a 15 volt reg, like this:

Image

or for a really quite unit, something like this:

Image

The Forum-Vibe power sections can be run whichever way you want, you can do like the original and use the raw V+ power on the LFO and a simple resistor-cap (470-Ohm/220uF->470-Ohm/220uF) supply, or you can run the LFO off the raw power input and use a LM7815 on the audio section, or you can run both sections with their own regulated supply, it's all there for your choice

The v1 PDF showed a hookup "suggestion" but that was removed from the new rev-2 PDF because it's really supposed to be up to you what you wan't to do. The Forum-Vibe is not a newb build so one is kind of expected to know their way around simple power supply circuits. Many folks already have a PS on their pedal board and just use that.

If you choose to run a single supply, for convienience on the v2 PCB two pads have been added for bridging the two power sections together highlited here for clairity:

Image

It can run off lower voltages but vibes seem to sound best in the 15-24v range.

Again, very nice work.

-Brad

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Redhouse
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Post by Redhouse »

BTW, are those the NSL7532's from Small Bear you're using?

And are we going to hear a sound clip? :thumbsup

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Post by coi2001 »

yes indeed, combining the power supply is a great option, nice planning. I really liked the flexibility afforded by the FV board.

I used the 7532s from SB. SB also has the rev. audio dual pot. As for sound clips, I need to get working on it!
thanks
Costantino

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Post by Redhouse »

I took the info from my post above and added an additional page to the end of the Forumvibe2.pdf to include this info. Anyone can re-download the PDF if they choose to here: http://classicamplification.net/forumvi ... e_File.htm

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Post by DrNomis »

This has inspired me to do some restoration work on my Univibe build.... :)
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Post by DrNomis »

I just found my Univibe under my bed,it needs a couple of new 1/4 inch sockets plus a couple of 3PDT footswitches,since I'm going to have to rewire it,I thought I would do a complete job of it and replace the original PCB with the ForumVibe PCB,the original has some tracks missing around the lamp section,which I had to kludge a bit to get it working again,some of the tracks were etched too thin anyway,and the ForumVibe has some really interesting mods that I would like to implement,I always had trouble with setting the trimpot for the lamp with the lamps I was using(12V/60mA types),so there's enough excuses to revamp it... :)

Will post some pics after the work's finished,so stay tuned.... :)
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Post by coi2001 »

This is a power supply for the Forum Vibe. I started from the schematic in the Forum Vibe pdf (thank you Brad!). I used an unregulated wall wart providing 19V DC. Played with the size and placement of the filter capacitors to eliminate the AC hum. The phase stage seems to need the cleanest power and placing a 1000uF cap between the output of the regulator and ground does the trick. This seems to be more effective than placing the same capacitor across the input the regulator or across the output of the wall wart. With this power supply setup the vibe is as quiet as when supplied with batteries. I thought I would share in case someone is interested.
Costantino
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Post by R.G. »

Just for completeness, the stock univibe circuit can usually be run from a 9Vdc adapter feeding an LT1054 upverter/doubler. I would not have bet that would work but it's been done.

The Neovibe board available from GGG has the rectifiers and filter to make DC from AC on the PCB like the original Univibe had, and also includes a spot for a 7815 regulator which feeds the phase section only, for lowest noise.

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Post by coi2001 »

Thank you RG, running it from 9V is an attractive possibility. Why is the inverter-doubler needed? Could you run it from a 1044? Theoretically one chip (100mA) feeding two regulator would suffice. Correct?
Costantino

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Post by R.G. »

coi2001 wrote:Thank you RG, running it from 9V is an attractive possibility. Why is the inverter-doubler needed? Could you run it from a 1044? Theoretically one chip (100mA) feeding two regulator would suffice. Correct?
Costantino
The inverter-doubler is used just in doubling mode to get to 17V - diode losses keep this under a perfect 2X. The original circuit can be modified to work from 9V only, but it requires some significant tweaking.

You could run it from a 1044. I don't recommend it because the 1044 has an absolute maximum DC input voltage of 10.000000V. I've had a few die on me. The LT1054 does much the same job, but has a higher input voltage specification, and will not die on AC power adapters which go close to 10V.

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Post by coi2001 »

Good to know, it's always a pain to have different power adaptors for each effect.

On a different note, I was impressed to read in the analogman effect book the very complimentary remarks of Fumio Mieda, the inventor of the univibe, concerning your technology of the Univibe article. I was not aware of it and would like to congratulate you!
Keep up the good work! We all appreciate your insights.
Costantino

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Post by R.G. »

coi2001 wrote:On a different note, I was impressed to read in the analogman effect book the very complimentary remarks of Fumio Mieda, the inventor of the univibe, concerning your technology of the Univibe article. I was not aware of it and would like to congratulate you!
Keep up the good work! We all appreciate your insights.
Costantino
?????

Wow I had no idea. Is that on line somewhere?

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Post by coi2001 »

R.G. wrote:
coi2001 wrote:On a different note, I was impressed to read in the analogman effect book the very complimentary remarks of Fumio Mieda, the inventor of the univibe, concerning your technology of the Univibe article. I was not aware of it and would like to congratulate you!
Keep up the good work! We all appreciate your insights.
Costantino
?????

Wow I had no idea. Is that on line somewhere?

RG I am amazed you did not know and nobody picked that up before!
Tom Hughes: Analog Man's Guide to Vintage Effects, 2004, page 175
He is very complimentary and referring to your Univibe tech article he says "I was very impressed by his analysis". This is big, definitely worth putting in your CV!
Congratulations again
Costantino

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Post by Redhouse »

coi2001 wrote:Thank you RG, running it from 9V is an attractive possibility. Why is the inverter-doubler needed? Could you run it from a 1044? Theoretically one chip (100mA) feeding two regulator would suffice. Correct?
Costantino
In my experience the vibe's sound best at 15V or greater, dunno why, but they do.

I've been bumping mine up to 18V recently and may take them up to 22V before I'm done. JC runs his at the full 24V.

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Post by Hotrats »

the original Vibes ran at around 25vdc, anything lower starts sounding wimpy
same goes for other class-A circuits

some other comments about this:

http://www.madbeanpedals.com/forum/inde ... pic=407.30

some tracks recorded with a viva Analog custom Vibe :

http://www.myspace.com/timbutlerwinnipeg

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Post by marshmellow »

Hotrats wrote:the original Vibes ran at around 25vdc, anything lower starts sounding wimpy
same goes for other class-A circuits
Funny. You mean like virtually all other discrete effects pedals? (Leave out ICs here, because depending on type there are class A/B/AB/C output stages) They sure all sound really wimpy at 9V or even lower supply voltages. :roll:

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Post by R.G. »

Hotrats wrote:the original Vibes ran at around 25vdc
Interesting.

The ones I measured were about 18-19Vdc unregulated, and the R-C sections dropped that down to about 16Vdc on the audio phase line. But there were at least two releases of the PCB, perhaps they had different versions of the power transformer too. The 16Vdc is why I picked a 7815 regulator for the first Neovibes, back in the 90s. I've had lots of testimony from builders over the last decade or so that those duplicate the original Univibe sound if built correctly, even with (only) 15V in the signal line.

No matter. The Neovibe uses a three terminal regulator to get its quiet analog line voltage. It's easy enough to put in a 7818 7820, or 7824 if you have enough raw voltage to run the regulator. They all fit the same hole pattern. You need at least 2V of headroom for a three-terminal to regulate.

Getting the raw DC to regulate from then becomes the trick. An easy possibility is a wall wart putting out 18Vac to 22Vac. Another is to use a charge pump as a tripler, not doubler, to get 26V or more out of a 9V battery or DC power supply.

Be aware that the power dissipation on the lamp driver goes up as you run up the power voltage for it. The lamp driver was a weak spot in the original design. I've repaired a number of original univibes with dead lamp drivers. They get hot in operation. So if you ramp up the raw lamp voltage, you need to worry a bit about what the lamp driver does. Using a TO-126 or TO-220 lamp driver can make it take the heat, or you can foist some of the heat off on a zener in series with the lamp to eat up some of the voltage that's not used for the lamp. Or you can dink around with finding a high voltage lamp. People do report changes in sound with different lamps, perhaps as a result of the different time constants of the filament heating and cooling to make the light pulses.

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Post by DrNomis »

Hi RG,

I downloaded a copy of the Forum Vibe PDF,etched a board from the included artwork,implemented all the mods,replaced the 47k input resistor with a 2M2, guess what?....it worked first time...,I'm very happy with it.... :)


My build uses a 22V DC/450mA plugpack, I'm getting 26V DC going to the LFO and lamp driver circuit,the rest of the circuit gets 15V DC, it sounds great.... :)
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.

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Post by DrNomis »

I replaced the LFO and lamp driver thransistors with MPSA 14 Darlington Pair Transistors, they work great.... :)
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.

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Post by coi2001 »

This is my completed forum vibe powered by a 9V DC supply. The output of the charge pump (daughter board to the left) feeds into the regulators (right) and from there to the board.
Forum vibe guts.jpg
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These are the vero and the corresponding build of the charge pump
Power_for_univibe_1054 copy.pptx
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Charge pump.jpg
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These are the vero and the build of the regulators, I left the capacitors in from a previous version fed form a 24 V AC supply.
Power_supply_FVibe.pptx
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