Voodoo Labs - Tremolo  [schematic]

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drewl
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Post by drewl »

Anyone have a schema or general layout for one of these?
A friend wants me to make him one, thanks.

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heyveno
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Post by heyveno »

Hi,

A friend want i make for him a transparent tremolo, he love the Strymon Flint, but i don't find a schematic or layout of this, and he doesn't care about reverb.

He got a Carl martin V2 surf trem, but he said it's alterate too much the guitar sound.

I don't know trem, so have you got any idea of a trem model i can do?

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Post by soulsonic »

you could do a tremolo where it's just a buffer with a series resistor and LDR to ground after it to make a basic voltage divider. Rig up something to flash an LED at the LDR and that's about it. My guess is it would be pretty "transparent", since the buffer would would prevent the voltage divider from loading down the guitar's signal. Tone should be unchanged by this.
There was a popular circuit like this using a fan that was making the rounds a few years ago. Don't remember the name.
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Post by ppluis0 »

Hi Folks,

Below is the schematic of a three knob Voodoo Labs Tremolo that I trace several years ago thath employs a combination of LED and LDR as Soulsonic suggest.
The lowest op amp is the buffer that manage the audio signal and the three remaining ones makes the oscillator and led driver.
Take into account that the two leftmost op amps are connected as quadrature oscillator requiring the use of a dual 100K potentiometer, and the produced output is almost a perfect sine wave.
The 1M pot change the shape of modulating wave from sine to trapezoidal to square as the gain increases. The remaining 50K (B) pot tied to the output jack is the intensity control.
The only adjustment required is by means of the 5K trimpot to achieve 4.2 mA peak to peak with the 1M pot set to minimun gain.
Cheers,
Jose

Image

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Post by heyveno »

thx a lot, will try

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Post by jimmyjazz »

ppluis0 wrote: 18 Mar 2019, 02:53 Hi Folks,

Below is the schematic of a three knob Voodoo Labs Tremolo that I trace several years ago thath employs a combination of LED and LDR as Soulsonic suggest.
The lowest op amp is the buffer that manage the audio signal and the three remaining ones makes the oscillator and led driver.
Take into account that the two leftmost op amps are connected as quadrature oscillator requiring the use of a dual 100K potentiometer, and the produced output is almost a perfect sine wave.
The 1M pot change the shape of modulating wave from sine to trapezoidal to square as the gain increases. The remaining 50K (B) pot tied to the output jack is the intensity control.
The only adjustment required is by means of the 5K trimpot to achieve 4.2 mA peak to peak with the 1M pot set to minimun gain.
Cheers,
Jose

Image
Hi, not been on here for a few years! You mentioned it being a 3 knob trem, isn’t there a 2 and a 4 knob version only? Sorry if I’ve misunderstood. Both versions I’ve seen inside use a quad op-amp as opposed to 2 dual op-amps as shown in your (excellent by the way!) schematic. Matt

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Post by ppluis0 »

Hi jimmy,

Thank you very much for your compliments !!!

The pedal I investigated had only three pots.

That was more than 25 years ago and I can't find information about this exact model on the web as only images of the two and three knobs boxes appear.
In any case, it seems that the four potentiometer model would have more gain than unity in the audio stage and they have added a master volume control.

If you had access to a current model (2 or 4 knobs) it would be nice to be able to compare what is inside each of them.

Cheers,
Jose

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Post by ppluis0 »

Found this gutshot on the web belonging the two knobs model:

Image

At first glance the oscillator appears to be similar to the one in the diagram above and the slope control is replaced by a two position jumper... :roll:

Cheers,
Jose

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Post by jimmyjazz »

Thanks for the reply! My 4 knob version is very noisy, need to get it sorted as I love it. I’ll probably end up tracing it and posting the results but currently have no time whatsoever!

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Post by jimmyjazz »

P.s I’ve never heard of/seen a 3 knob version!☹️

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Post by ppluis0 »

There is an internal image (also found searching the web) of the 4 knob model:

Image

Cheers,
Jose
Last edited by ppluis0 on 09 Nov 2022, 02:55, edited 1 time in total.

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Post by jimmyjazz »

Cheers. When I get chance I’ll trace mine and post the schematic, the 4 knob schematic doesn’t seem to exist on web!

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Post by FuzzMonkey »

I wonder if the volume control of the four-control version is just a the pot wired as a variable in the feedback loop of the op amp in the audio path?

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Post by Bernardduur »

I got one in for some TLC.
It needed a new switch

Here's the schematic. For soms pics check my blog or insta
Voodoolabs - Tremolo 4 knob.JPG
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Post by Ichabod_Crane »

Thanks for the schematic.
Let see if I got everything. That H11F3 is about the bypass switching? Can we ignore it in case of true bypass version?
Then I see, in the old version picture, two knobs I guess, that has a PULSE / SWELL... switch or something?

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Post by Bernardduur »

Ichabod_Crane wrote: 21 Jan 2024, 09:13 Thanks for the schematic.
Let see if I got everything. That H11F3 is about the bypass switching? Can we ignore it in case of true bypass version?
Then I see, in the old version picture, two knobs I guess, that has a PULSE / SWELL... switch or something?
You can omit the hf section for a normal true bypass

I don't know anything on the pulse / swell switch. Maybe its an old version of the slope knob
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Post by Ben N »

Ichabod_Crane wrote: 21 Jan 2024, 09:13 Thanks for the schematic.
Let see if I got everything. That H11F3 is about the bypass switching? Can we ignore it in case of true bypass version?
Then I see, in the old version picture, two knobs I guess, that has a PULSE / SWELL... switch or something?
It IS true bypass, as far as I can see, albeit in an unusual configuration. In bypass mode, the input passes straight through to the output. I wonder what advantage there is to doing it this way over simply attaching the pole of the switch to the coupling cap and the throws to the input jack and ground, in the conventional fashion. Does the use of the vactrol minimize popping?

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Post by Lani »

I believe the main advantage is the use of a DPDT instead of a 3PDT. It may be quieter too, like you mentioned....

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