Univibe issue - bulb not bright / deep enough flashing.

[nznat]

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

 

[Locrian99]

I socketed my Ldr and led and tried several combinations before I settled which is what I would suggest.

 

[Nic]

whos the OP?

OP = Original Poster, or similar... so it's you

 

[nznat]

My only concern with using this anecdote for the Univibe is that the bulb has different on/off and intensity characteristics as the LED in the Abyss.

The best LDR I’ve used is the 9203.

5-20k Light Resistance.

20M Dark Resistance.

20MEG!!!! wouldnt that be so low that it would thumb the speaker? someone just stated to use 500K dark. man some different info coming in

 

[Big Monk]

20MEG!!!! wouldnt that be so low that it would thumb the speaker? someone just stated to use 500K dark. man some different info coming in thats not helping here as they specs are WAYYYYYY different to each other.

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.

 

[nznat]

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.

talking about two different circuits? huh? so this isnt about my circuit anymore, just a general conversion about anything at all? dam

 

[Big Monk]

talking about two different circuits? huh? so this isnt about my circuit anymore, just a general conversion about anything at all? dam

Try new LDRs.

Preferably one close to the specs I quoted above.

The issue now is your light resistance.

 

[nznat]

Try new LDRs.

Preferably one close to the specs I quoted above.

The issue now is your light resistance.

sorry which specs? so many people tuning in with massively random comments and part specs? dark and light specs?

 

[fig]

Apologies for any confusion. Best of luck.

 

[nznat]

Apologies for any confusion. Best of luck.

what do you suggest,

 

[Big Monk]

sorry which specs? so many people tuning in with massively random comments and part specs? dark and light specs?

 

[Haz]

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?

 

[Bricksnbeatles]

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.

 

[Haz]

Ok I will try this