UVICS - Univibe In a Crybaby Shell

[R.G.]

Voltage readings are the next thing to do, OK.

[aryk]

I noticed in the build docs not to touch the (-) power supply to the shell. I'm using ac and I think I may have done just that. Will this be an issue?

[R.G.]

It's probably OK if you just *touched* it to the shell. Wiring it to the shell or using a metal-body power jack for getting AC will definitely cause problems.

The problem lurking here is one that I encountered in my own first Univibe clone, and one that persists because of the design. The original Univibe used a power transformer inside the enclosure and took a 120V power line outside the box to a wall socket. This is very dangerous and unnecessary for cloners, so I made the first of my vibe clones work with a wall wart putting out AC. I left the rectifier/filter on the PCB, but brought out the wires to feed low voltage AC into the power supply on the PCB.

For shielding reasons, the metal box must be tied to signal ground. So if either of the incoming AC wires touch the box, this shorts AC to signal ground. Worse, on the PCB, the AC wires are alternately connected to signal ground by a forward biased diode in the full wave rectifier, so you have the full voltage of the AC power 'shorted' by a diode. It causes problems. If you use a DC adapter, you can't use a metal frame power jack because then the DC incoming 'minus' wire will be one diode drop below signal ground, again because of the original design's rectifier.  The simplest solution to both of these problems is to use a wall wart for only the vibe clone and make the power jack have a plastic body so neither of the shorting problems happens.

Whether this kills components if you get it wrong is uncertain. Maybe, maybe not. Could kill the rectifier diodes, possibly other parts.

Best is to make it be correctly wired, then do the DC voltage thing for checking out whether the circuit is working right.

[aryk]

I'm using a one spot on a dc jack. Could this be an issue? How would I be able to check any damage caused?

[R.G.]

Exactly how did you populate and wire the power inlet? Did you use a bridge rectifier or not? Or just the DC wiring diagrams?

[aryk]

I just used the dc wiring diagram and omitted the rectifier. One thing I find strange is that I get bypass in both on/off? I triple checked the wiring and nothing was wrong with that that I could see. Here's some pics if you can make anything out. I added a clear shaft pot with led in it for the depth pot.


I used an audio probe and everything is good up until R4 and Q4. I get signal on the east/right lead of R4 (looking at the populated side with trimmers on the right) and only get signal to the middle leg of Q1. Replaced Q1 and nothing changed. I'll be posting reading's here in a couple.

[aryk]

Voltage readings:
Socket:
C: 0
D: 18.25vdc
J: 9.02
K: 9.02
E: 9.02
F: 8.77
G: 8.81
H: 8.81
X:
I:
1D: 11.39
1C: 9.02
M: 8.70
L: 8.83
N: 9.02
1B: 9.02
1A: 9.01
B: 9.02
A: 8.96

IC1: IN:9.02 G:0 OUT:9.01
U1: 1- 1.70, 2-5.05, 3-0.0, 4-0.0, 5-9.45, 6-1.41, 7-2.54, 8-0.0
U2: 1- 9.02, 2- 8.6, 3- 9.02, 4- 9.02, 5- 9.02
(used 2N5088's for Q1-12,14)
Q1: C- 8.54, B- 8.07, E- 9.02
Q2: C- 8.97, B- 8.55, E- 9.01
Q3: C- 9.01, B- 8.55, E- 9.01
Q4: C- 9.01, B- 8.90, E- 8.61
Q5: C- 9.01, B- 8.61, E- 9.02
Q6: C- 9.01, B- 8.90, E- 8.61
Q7: C- 9.01, B- 8.61, E- 9.02
Q8: C- 9.01, B- 8.90, E- 8.61
Q9: C- 9.01, B- 8.61, E- 9.02
Q10:C- 9.01, B- 8.61, E- 9.0
Q11:C- 9.02, B- 7.42, E- 8.80
Q12:C- 9.02, B- 8.81, E- 9.02
Q14:C- 9.01, B- 8.90, E- 8.80
Q13:C- 8.44, B- 8.89, E- 9.02
Q15:C- 9.01, B- 9.01, E- 8.60

[R.G.]

It'll take some time to digest, but I think you have power problems.

Let me chew on it a bit. There are some obvious problems, but I think they may have a common cause.

[aryk]

Thank you I noticed something strange also. My ground from board to output jack had 9.02v? I was connecting the (-) lead from the LED to it also, don't know if that was where the voltage was coming from but thought I'd throw that out there. I checked the lead directly and got 0v then the ring of the out jack and got 9.02v and then the pad where the ground wire was coming from on the board and got 9.02v so I assume that's where its coming from.

[R.G.]

Yeah, that was one of the obvious problems.

I'm taking that you built this with the voltage doubler to make 17V out of 9V from an adapter, right?

I think that either your wiring (or mine, if I hosed that up!    ) has a problem, or there is a biggish issue with the voltage converter setup.

I've been out all day, just got back to this.

[aryk]

Yeah I used the doubler. What if I replaced the voltage converter IC? I rechecked those wires 3 times now and didn't come across any errors. But I know that I can stare at the same thing and not notice the problem till someone points it out. I'm sure plenty of people have built this according to your schematics and been fine with it. Seems I've been cursed lately with builds this is my second one where I can't figure out the issue lol.

[aryk]

Another thing to add is that C28 and C29 have a 15V rating. I didn't notice this until now...

[R.G.]

OK, first thing is to get the power supply running correctly. I believe you used the version with the power converter on a separate little PCB, yes?

So first, disconnect that small board from the main PCB by temporarily unsoldering the wires, and put a 1K resistor across its output. Yep, the two caps on that board need to be rated the next step up in voltage, probably 25V. If you're ordering parts, get a fresh voltage converter. While the parts are coming, try out the converter board with just the 1K resistor load.

Mmmmm. Just went through the voltages on the converter chip. Is the voltage on pin 5 really 9.45 and pin 8 0.0V??  The PCB traces connect pin 5 to ground and pin 8 to the incoming voltage. Is there a chance of a measurement error on those?

While this is going on, or when you reach a stopping point, you can power the rest of the circuit from two 9V batteries in series instead of the disconnected power converter board and see what the signal board does on the right amount of DC. Two 9V's in series will run it for a while, long enough to check out the signal function. Be sure to get the polarity correct if you do this.

[aryk]

So I wired the two 9v in series and got nothing. Also changed out the caps. I do have another voltage converter ic on hand as I usually order two if I need one. But wouldn't there first be an issue with the ratings? I didn't get you false readings lol sorry I had 5,6,7, and 8 switched around. Anything else to change?

[R.G.]

So I wired the two 9v in series and got nothing.

When you say "got nothing", did you wire the two batteries directly to the PCB, substituting these for the converter PCB? What do the transistor voltages change to with 18V on the PCB? If the PCB pulls down two batteries to 9V, there are other problems on the PCB.

Also changed out the caps. I do have another voltage converter ic on hand as I usually order two if I need one. But wouldn't there first be an issue with the ratings?

Maybe. Did you try the test of just the converter PCB with a 1K load resistor? What voltage does it put out? Try that before changing out the converter IC.

I didn't get you false readings lol sorry I had 5,6,7, and 8 switched around. Anything else to change?

No problem. I always have to double check my own pin numbering. I checked the PCB traces manually, and they look like they go to the right places if I didn't miss something.

Try the two-batteries test on the PCB and report back the transistor (and voltage regulator) pin voltages, and also try the converter board with a 1K as a load.

[aryk]

I did wire them directly to the 18v in and ground. (when I say I got nothing I meant nothing changed on the board). I'll try and get the tranny values asap.

Maybe. Did you try the test of just the converter PCB with a 1K load resistor? What voltage does it put out? Try that before changing out the converter IC.

I put a 1k on the lugs where the 18v leads were at if that is what you meant? I didn't happen to check the ratings I'll do that when I get the tranny values tonight. I'll get back to you with results.

Thanks for all the help

[R.G.]

No problem. This version you're building is the result of a hardy soul who built the first version and got his working, providing me with some valuable info about how it might be easier for others to build. So this has worked before. We'll get there.

[endorphin]

Hello  ! Its been a while.

I finally got back into this. From your instructions R.G. I omitted the bridge rectifier and went with a straight 18v DC supply to pads K and J using the correct polarity, jumpers, and the plastic jack.

For the first time the UVICS powered up correctly and the bulb came on. Well so far I get a signal when turned on but no Univibe effect just a clean boosted signal  . Now I've checked my wiring and traces plenty of times and all seems to be correct.

The one thing concerning me is when I first built the effect I did not use any sockets for the trannies and my soldering iron gets pretty hot. I have sockets now and backup parts if needed. So could you let me know what you think?

I guess meanwhile I can get some voltage readings together but also to add I am not using the baby board!

[R.G.]

First questions I'd have are
1. is the lamp pulsing on and off, controlled by speed pot setting?
2. do you have a proper light shield over the LDRs and lamp?

[endorphin]

Yes the lamp is pulsating on and off but only at a fairly low luminosity compared to how bright it can get. As I brighten the bulb with the trimpot it does not pulsate, don't know if that is normal
And yes the speed pot effects the lamp as it should except I have to swap the direction of its sweep.

It is a dual ganged pot both 100k ohm "A" taper. Seems that I'll have to do some tweaking though, as only a small portion of its travel is usable but I'll worry about that later.

The light shield seem perfect in my opinion. A black rubber end cap with a shiny metallic wrapper material lined in the sides and top. Perfect size, height, and flesh to the board. Whenever I tested I had the cap on.

My god man you must be helping a dozen other univibe builds!