Univibe LFo at 9 volts

[Atodovax]

Hello everyone. I want to change the lfo of my EQD THE DEPTHS board and i will do it on the same board with the components floating around. Do you know if the original UNIVIBE LFO will work at 9 volts or if i have to change any value? Of course im going to use a small 9volt lamp. Thanks

[idy]

Every time I see a univibe it is going on more than 9v. That LFO is the doggiest part (next to the right bulb.) Very idiosyncratic (sometimes locks up at slow speed) and needs volts.

Anyone seen a straight up Univibe without a charge pump or 18v supply?

[antonis]

Of course im going to use a small 9volt lamp.

Grrrrrrr...!!!

[Atodovax]

Of course im going to use a small 9volt lamp.

Grrrrrrr...!!!

Heheh good to see you again Antonis. Come on, i have to save this board hehe... i can totally change the lfo to the original Univibe with just few components floating. But before doing it, i just need to know it it will work at 9 volts

[antonis]

i can totally change the lfo to the original Univibe with just few components floating. But before doing it, i just need to know it it will work at 9 volts

I'm not sure if you have understood that lamp/bulb driving isn't LFO's matter... 

Implement any LFO you like and wire itss output on a stage capable to drive the lamp..
(BOTH from voltage AND current viewpoint..)

[Atodovax]

i can totally change the lfo to the original Univibe with just few components floating. But before doing it, i just need to know it it will work at 9 volts

I'm not sure if you have understood that lamp/bulb driving isn't LFO's matter... 

Implement any LFO you like and wire itss output on a stage capable to drive the lamp..
(BOTH from voltage AND current viewpoint..)

Well but as far as i understand it, the Lamp driver in the Univibe and THE DEPTHS its pretty much the same, right?. Can i just replace the driver transistor with a darlington? From what i understand, the LFO's output goes to the depth control and feeds the base of a darlignton via a coupling cap. I though the LFO had to be changed also .

[antonis]

Can i just replace the driver transistor with a darlington?

Plz, do it..!!

[Atodovax]

Can i just replace the driver transistor with a darlington?

Plz, do it..!!

Will try that and report back
I have the feeling that you are mad at me somehow

[antonis]

I have the feeling that you are mad at me somehow

(definately not..!!)

[Atodovax]

I have the feeling that you are mad at me somehow

(definately not..!!)

Ok well... heheh... i managed to make it "work" . Changed the deiver transistor for a MPSA13 and the light bulb now lights up very dim but lights up. The problem is that the LFO will latch when the depth knob is maxed or the rate pot is maxed... I tried it at 18 volts and the lamp glows super well and the LFO works much better without latching at any position. Any ideas about the latching problem? I want to use it with 9 volts ideally. Also, im using fast LDR with low resistance, so i dont need a lot of light. I just want to know why its not working when maxed

[pacealot]

on a stage capable to drive the lamp..
(BOTH from voltage AND current viewpoint..)

Every time I see a univibe it is going on more than 9v. That LFO is the doggiest part (next to the right bulb.) Very idiosyncratic (sometimes locks up at slow speed) and needs volts.

I think this might be what Antonis and idy are getting at. I don't think the traditional Univibe lamp/LFO circuit can work correctly at 9V. I assume (thereby making an ass out of u and me  ) that, when underpowered, the lamp driver acts as a load on the LFO, which breaks the oscillation at one extreme or other (someone please correct me if I have this wrong).

I've had problems getting one to run consistently even at 18V (admittedly I'd tweaked the LFO for a slightly wider osc range, which also pushed it past its limits) and found that it required at least 20v up to 24V, and a nice massive TO-220 Darlington driver transistor as recommended by RG, to reliably blink and not break across the whole range of the speed pot (and also not fry the aforementioned driver tranny).

[Atodovax]

on a stage capable to drive the lamp..
(BOTH from voltage AND current viewpoint..)

Every time I see a univibe it is going on more than 9v. That LFO is the doggiest part (next to the right bulb.) Very idiosyncratic (sometimes locks up at slow speed) and needs volts.

Thanks for replying .
What i really dont get is that the lfo works perfect at 9volts qith an LED. No problem at max or min Rate / depth. The problem is qhen i hook a lamp instead of an LED . Any ideas?
I think this might be what Antonis and idy are getting at. I don't think the traditional Univibe lamp/LFO circuit can work correctly at 9V. I assume (thereby making an ass out of u and me  ) that, when underpowered, the lamp driver acts as a load on the LFO, which breaks the oscillation at one extreme or other (someone please correct me if I have this wrong).

I've had problems getting one to run consistently even at 18V (admittedly I'd tweaked the LFO for a slightly wider osc range, which also pushed it past its limits) and found that it required at least 20v up to 24V, and a nice massive TO-220 Darlington driver transistor as recommended by RG, to reliably blink and not break across the whole range of the speed pot (and also not fry the aforementioned driver tranny).

[Rob Strand]

Hello everyone. I want to change the lfo of my EQD THE DEPTHS board and i will do it on the same board with the components floating around. Do you know if the original UNIVIBE LFO will work at 9 volts or if i have to change any value? Of course im going to use a small 9volt lamp. Thanks

Why change the LFO?   What do you expect to improve?

Perhaps all you need is to add a buffer and/or LED/LAMP driver *after* the existing LFO.

[antonis]

What i really dont get is that the lfo works perfect at 9volts qith an LED. No problem at max or min Rate / depth. The problem is qhen i hook a lamp instead of an LED . Any ideas?

Maybe 'cause lamps and LEDs are different devices ..??
(e.g. LEDs work with DC where Lamps work both with DC and AC or LEDs don't exhibit "cold" resistance ..)

P.S.
I presume you have to study in depth R.G.s analysis http://www.geofex.com/article_folders/univibe/uvfrindx.htm, especially for LFO and Lamp driver..

[Rob Strand]

The basic structure of the EQD THE DEPTHS
https://imgur.com/8R4keTO

looks very similar to the Univibe.   The oscillator itself is different but really it's the driver part that needs work.

JC Maillet makes a few good points about driving the lamp and biasing,
http://www.lynx.net/~jc/pedalsUnivibe.html

[Atodovax]

Hello everyone. I want to change the lfo of my EQD THE DEPTHS board and i will do it on the same board with the components floating around. Do you know if the original UNIVIBE LFO will work at 9 volts or if i have to change any value? Of course im going to use a small 9volt lamp. Thanks

Why change the LFO?   What do you expect to improve?

Perhaps all you need is to add a buffer and/or LED/LAMP driver *after* the existing LFO.

Hi Rob! I dont intend to improve it, its just that it was not working at 9volts with a lamp. I though maybe i could do an easy modification for that. I swapped the driver transistor gor a Darlington and while that made the lamp glow, the LFO now stalls at max speed or max depth

[Atodovax]

What i really dont get is that the lfo works perfect at 9volts qith an LED. No problem at max or min Rate / depth. The problem is qhen i hook a lamp instead of an LED . Any ideas?

Maybe 'cause lamps and LEDs are different devices ..??
(e.g. LEDs work with DC where Lamps work both with DC and AC or LEDs don't exhibit "cold" resistance ..)

P.S.
I presume you have to study in depth R.G.s analysis http://www.geofex.com/article_folders/univibe/uvfrindx.htm, especially for LFO and Lamp driver..

Thanks Antonis! Will do that

[Atodovax]

The basic structure of the EQD THE DEPTHS
https://imgur.com/8R4keTO

looks very similar to the Univibe.   The oscillator itself is different but really it's the driver part that needs work.

JC Maillet makes a few good points about driving the lamp and biasing,
http://www.lynx.net/~jc/pedalsUnivibe.html

What kind of "work" do you tjink might be suitable for a bulb lamp to run at 9volts? Hehe

[antonis]

What kind of "work" do you tjink might be suitable for a bulb lamp to run at 9volts? Hehe

Hehe..

Perhaps all you need is to add a buffer and/or LED/LAMP driver *after* the existing LFO.

[Atodovax]

Perhaps all you need is to add a buffer and/or LED/LAMP driver *after* the existing LFO.

[/quote]
Well isnt there an existing LAmp driver already there? You mean to add a second driver?