Original effects with schematics, layouts and instructions, freely contributed by members or found in publications. Cannot be used for commercial purposes without the consent of the owners of the copyright.
vintagecharlie wrote:Dave, that video on youtube by fuzzfaceexp is a replica uni-vibe. You can see that the onclosure has screws and some other small details that give it away. I had already found this guys blog in japan where he had additional pictures of the build. He didn't say what bulbs or ldrs were used and he hasn't answered my message that i wrote to him a long time ago about that. So i guess he will keep it to himself. But yeah, that thing sounds really like what i would expect from an original.
Do you have his e-mail or other contact?
I wish try to contact him.
I have to inform that I've got very good results this photoresistor Clairex CL7P5HL.
I think that "the secret of the CDS type" is in the parameter (Colour Temp °K) What we need is that the response of the LDR stays constant throughout any wavelength. There are many curves that shows that at Clairex or Silonex datasheets...
Coincidence or not, this type of LDR is the one with the fastest response (rise and fall time).-
I use last week the type 5H and souds excelent! The modulation in low freciencies was WOW / Awsome!!! Is warm, fast and agresive.
In middle frec. Is is very good. I think it can be better, but for now I'm happy how it sounds.
I'm still looking for the best replacement of CDS LDR, and when I find it I'll post the p/n.
I hope for the weekend to publish an audio file of my UVs.
PS: ...and YES! I'm out of mind in spending a lot of time and money in studying the best replacement of LDR for our UVs... I've spent around 200 u$d in LDR
Hi guys PLEASE spare a word or two on power supply..
I am based in Europe, 220/230v acdc.
I bought a small blue 220/230v to 25v power mains transformer, will it do the trick?
please HELP ME
Dave, thank yopu big time for this tip on the LDR's - it is the thing that many pro and amateur builders want to keep a secret when it's about the univibe, as the ldr and bulb combo is the heart of it.
Will look into the LDR's you mentioned. Can you elaborate on what bulb you were using with them - as the combo of ldr+bulb is the key, from what i understand.
I hope to have the parts together for my own build soon and can't wait to start the build.
Dave, any sound clips would be highly appreciated!
Whilst waiting for help, i am soldering a diode bridge and a 1000uf 63v cap in series to bring 24v ac to 24v dc from the transformer's 230v ac in to 24v out.. am i doing the right thing?
!
I do not have the Original Manual, just the Replica Files/images.
Is it the same if i power it with ac or dc?
I dont think so... But in the case direct current is needed, does the chain 220vac transformer to 24vac out>diode bridge+cap>24vdc out>replica board would be ok?
It is the first time i deal with mains current, i wouldnt particularly want to die.
vintagecharlie wrote:How come nobody thanks Dave for this input?
Dave, thank yopu big time for this tip on the LDR's - it is the thing that many pro and amateur builders want to keep a secret when it's about the univibe, as the ldr and bulb combo is the heart of it.
Will look into the LDR's you mentioned. Can you elaborate on what bulb you were using with them - as the combo of ldr+bulb is the key, from what i understand.
I hope to have the parts together for my own build soon and can't wait to start the build.
Dave, any sound clips would be highly appreciated!
ough!
Man... is so difficult to say what is the real p/n of the bulb... I'm not keeping it in secret.
The way how I obtain it was looking and stirring in segregated old parts here at my job... in the workshop. The people who had this parts don't have idea for what it's used.
So I request it's for personal use and I took it.
I think is a common 328 or 327 lamp (I don't remember which one) 28v 40mA but without the bottom thread. So it's the same with two large terminals.
And for the LDR I'm using now CL7P5HL
!
I do not have the Original Manual, just the Replica Files/images.
Is it the same if i power it with ac or dc?
I dont think so... But in the case direct current is needed, does the chain 220vac transformer to 24vac out>diode bridge+cap>24vdc out>replica board would be ok?
It is the first time i deal with mains current, i wouldnt particularly want to die.
Easy man!
You can energized your circuit board with 24Vac (mine is with 18Vac) and when you converted to pulsating Vdc with the only poor diode you've got around 22Vdc on 1000uF Cap.-
If you chek the PWR supply empty, you will measure like 28Vdc (with your 24Vac transformer) but when you connect it that tension falls to 25Vdc aprox...
Hi dave.. Thanks a million.
Ok so my transformer is 200/230v ac to 24v.
Upon reading the geofex technology of the univibe it became clear that the circuit needs 24v DC.
I posted the question on the forum this morning, and then i went to my local supplier who told me how to convert from 24v ac to 24v dc. I just wanted to know how the replica circuit will operate under 24v dc. And generally if i am doing things right..
thanks Dave for your input on LDRs
i'm building a univibe clone as well, but with many popular mods, so it's not an exact replica of the vintage unit
anyway, i've had issues with the LFO section, in particular i noticed that at slower rates the bulb was pulsating weakly; at higher speed instead, the bulb-swings got more brilliant, and the resulting effect was much deeper (and nicer!)
i wanted to have this deep effect at slow rates as well, so i breadboarded the LFO circuit, and try to find a way for leveling the bulb brightness between slow and fast rates.
well, i discovered that the use of an MPSA13 for the bulb driver helps a LOT: Now i get bright pulses at slow rates too.
i know that using a darlington transistor here is not a new, but what is new is that it affect the pulses' brightness at slow rates.
another thing that i've experimented is about the 2 diodes:
if you use low V-drop ones (i.e. germanium diodes), the LFO would eventually stall;
and if you pull them off the circuit the oscillating becomes more symmetrical, closer to a perfect sinusoidal (if you have the BIAS trim and the OFFSET trim fitted, you can adjust the oscillation very well)
i'm still experimenting at the moment with these diodes, because i suspect that the "liveness" of the sound of the original pedal is also due to a non-perfectly symmetrical LFO: these 2 diodes seem to extend a little the middle part of each swing - but as i said i'm still working on it.
Masuto wrote:Hi dave.. Thanks a million.
Ok so my transformer is 200/230v ac to 24v.
Upon reading the geofex technology of the univibe it became clear that the circuit needs 24v DC.
I posted the question on the forum this morning, and then i went to my local supplier who told me how to convert from 24v ac to 24v dc. I just wanted to know how the replica circuit will operate under 24v dc. And generally if i am doing things right..
You don't need to convert nothing...
Just conect your transformer 24VAC into the board....
The circuit board contains the rectifier to convert de Vac to Vdc...
Intripped wrote:thanks Dave for your input on LDRs
i'm building a univibe clone as well, but with many popular mods, so it's not an exact replica of the vintage unit
anyway, i've had issues with the LFO section, in particular i noticed that at slower rates the bulb was pulsating weakly; at higher speed instead, the bulb-swings got more brilliant, and the resulting effect was much deeper (and nicer!)
i wanted to have this deep effect at slow rates as well, so i breadboarded the LFO circuit, and try to find a way for leveling the bulb brightness between slow and fast rates.
well, i discovered that the use of an MPSA13 for the bulb driver helps a LOT: Now i get bright pulses at slow rates too.
i know that using a darlington transistor here is not a new, but what is new is that it affect the pulses' brightness at slow rates.
another thing that i've experimented is about the 2 diodes:
if you use low V-drop ones (i.e. germanium diodes), the LFO would eventually stall;
and if you pull them off the circuit the oscillating becomes more symmetrical, closer to a perfect sinusoidal (if you have the BIAS trim and the OFFSET trim fitted, you can adjust the oscillation very well)
i'm still experimenting at the moment with these diodes, because i suspect that the "liveness" of the sound of the original pedal is also due to a non-perfectly symmetrical LFO: these 2 diodes seem to extend a little the middle part of each swing - but as i said i'm still working on it.
Excellent work...
So you recomend to me use some 1N914 or 1N4148 instead of the two cheap 4001 in LFO?
Or maybe better 1N270 (Ge)
The original is (Si) diode... not (Ge), but here it doesn't matter what kinda diode but how it sounds
DaveAir79 wrote:
So you recomend to me use some 1N914 or 1N4148 instead of the two cheap 4001 in LFO?
Or maybe better 1N270 (Ge)
The original is (Si) diode... not (Ge), but here it doesn't matter what kinda diode but how it sounds
no, don't use Ge diodes or the LFO would stall
Ge diodes are an extreme, and pulling off the diodes is the other: (maybe) the optimum is in the middle
i could be wrong, and i haven't any oscilloscope to confirm this, but i think that the forward V-drop characteristic of these 2 diodes affects the shape of the oscillation
so maybe we can find a couple of diodes that best suits our taste, choosing between different V-drops
it would be great if someone with an oscilloscope would confirm my impressions.
p.s. and there are ways t thank someone that are more sophisticated than pressing some hidden button somewhere - like actually saying or typing it, which i am sure i did
I've spent around 200 u$d in LDR 
