Univibe issue - bulb not bright / deep enough flashing.

nznat

nznat

Member
Im having trouble with a vibe build. Here's the thing. When i plug in the power supply, i see the bulb go brighter and deeper in the flashing mode, seems perfect, yet after about 1 second after i plug in the power supply it suddenly goes more dim, the depth of the flashing has gone much dimmer / less, thus the lush univibe tone is mostly gone because of this, doesn't sound correct anymore. Any ideas on power supply issues on the pcb or what part of the univibe circuit controls the power of the bulb itself? Can anyone point to these areas and caps etc that regulate the bulbs depth of flashing on the schematic attached so i can remedy this situation?
much appreciate your help
 
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I used the 5528 with a 330k (which if I remember right out it around 250k) in parallel in my the depths and am very happy with it. The part # for the abyss I believe has 500k which I’m sure would be fine.
 
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Big Monk said:
The light resistance in those LDRs is probably the culprit.

Data sheet says 150-300k when the generally accepted best sounding units have a range of 5-20k
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can you show me the proper range. 5-10k doesnt make any sense. light or dark etc.? what is the part number for the best vibes? and what is the best vibe? Hendrix original vibe was dark as anything, the brightness didnt exist until he cranked the amp. these days people keep trying to create a vibe that sounds like a concert volume bright tone, yet in the bedroom, yet thats "nothing" like the real univibe which was NOT bright sounding at all, it was uniform and organic "big and round". everyone is going for the bright, because they are not going to be playing loud. check this out:
 
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What we are referring to is the Ldr not the sound. So your Ldr when hit with a lot of light has a min resistance say 10-20k. When it’s dark it also has a resistance say 1M. Yours is have to look again when it’s light has like 200k and dark is 10m. That is why it sounds like a tremolo it’s not letting any signal through at 10m. I would try the gl5528 as was suggested it has good stats tayda has one similar stats that is around 500k dark I think. But in my albeit limited experience you want around 500k dark around 10-20k light. I’ve only built the one vibe that has 4 ldrs so the stats could be very different for yours.
 
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Locrian99 said:
What we are referring to is the Ldr not the sound. So your Ldr when hit with a lot of light has a min resistance say 10-20k. When it’s dark it also has a resistance say 1M. Yours is have to look again when it’s light has like 200k and dark is 10m. That is why it sounds like a tremolo it’s not letting any signal through at 10m. I would try the gl5528 as was suggested it has good stats tayda has one similar stats that is around 500k dark I think. But in my albeit limited experience you want around 500k dark around 10-20k light. I’ve only built the one vibe that has 4 ldrs so the stats could be very different for yours.
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great reply, thanks for that input. i have found a GL5528 that is local in my country. ill grab it and try.
 
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Big Monk said:
We are talking about two different circuits. The other poster is referencing the EQD Depths.

We are talking about the Univibe.

Thump the speaker? I don’t follow.
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talking about two different circuits? huh? so this isnt about my circuit anymore, just a general conversion about anything at all? dam
 
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I have pcb together bug get clean sound no vibe effect? Slight lfo hissing in background.
Bulb is flashing and trimmers work, pots appear working. I've tested all 5088 above hfe 600. Tried a different IC. If I install L78L12 oriented as on pcb bulb doesn't flash. Other way around it flashes but not vibe effect.
I suspect maybe wrong photocells?
Any clue where to start? 20221014_071920_1665721247140.jpg
20221013_233249.jpg6101939061326154520_PerfectlyClear_1665721069928.jpg
 
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You’re not testing it exactly as shown in the picture, are you? The ambient light of the room is a no go. You want to text the circuit in complete darkness- either make a light shield to go around the photocells and bulb; turn off all of the lights and rest in a totally dark room, or (least practically, in case you need to take it out agsin) test it after it’s all boxed up with the lid closed back up.
 
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