Optochopto: A wah based tremolo

[DWBH]

Can I use a CD4093 if I tie the 2 inputs together on each trigger?

[oskar]

Yes.

[Entrant_21]

Just an FYI, i built the boost portion of the circuit (on a new cleaner layout, if there is interest i will post it), and though the tone is nice and does add a certain character, it doesn't offer a lot of gain boost. If I could figure out how to goose it a little for more noticeable boost, it would really be a nice booster. any ideas?

Try reducing the 6.2M fb resistor to like 2M or something.. I think that'll work.

yeah, tried that, no dice. I wonder if just cascading it into a mosfet booster would retain the same tonal characteristics jus twith more volume.

try increasing the 10k resistor at the collector that should increase it..again i think. I'm fairly new to transistors, i mainly use op-amps etc.

[DWBH]

I just breadboarded this (used a CD4093). Glamorous video is on its way!
However, I didn't hook up the LED as is on the schematic. That way it wouldn't blink.
I hooked it up between the input and the output of the trigger - SUCCESS. It blinks now. I missed something.
Either way it's so cool. Wha + Tremolo = holy cow!

Here it is: http://www.vimeo.com/2709959

[DWBH]

I can see why it's called Optochopto. The LFO generates a square wave, giving that chopped sound.
Maybe another (more complex, although) LFO could be implemented, like the one on a tremolo (the Tremulus Lune, for example).

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There's another way of hooking the CD4093 up. Instead of tying (?) up the 2 inputs, one goes to +9v, and I've got one trigger just like the one on the 40106. Like this:


Can we get a sinewave, or a less square-y wave out of an oscillator of this kind?

Also, I'd suggest a 100k resistor in paralell with the resistor side of the vactrol (this is if its resistance is 10meg, like in most cases).

[dano12]

I can see why it's called Optochopto. The LFO generates a square wave, giving that chopped sound.
Maybe another (more complex, although) LFO could be implemented, like the one on a tremolo (the Tremulus Lune, for example).

---

There's another way of hooking the CD4093 up. Instead of tying (?) up the 2 inputs, one goes to +9v, and I've got one trigger just like the one on the 40106. Like this:


Can we get a sinewave, or a less square-y wave out of an oscillator of this kind?

first off, thanks very much for the clip--I would have probably never got around to it.

Yes, a triangle/sine LFO would be interesting, and certainly make it more versatile. I would imagine any LFO capable of driving the Vactrol would work.

[DWBH]

What clip? That hideous thing?
Just had a crazy idea: 4 wah's in series, each one controlled by an oscillator, with each wah tuned with different resonance and frequency peak. Yuck, it'd probably sound like crap.

[dano12]

What clip? That hideous thing?
Just had a crazy idea: 4 wah's in series, each one controlled by an oscillator, with each wah tuned with different resonance and frequency peak. Yuck, it'd probably sound like crap.

or add 8 pots and you have a zvex ooh wah

[DWBH]

Not sure if you were kidding or not, but I always thought the Ooh Wah was just a sequencer changing the pot's resistance of one wah.

I tried the oscillator setup like I said above, but as before, I only get oscillation it I connect the LED to the output and input of the oscillator. Strange.

ADDED LATER: If one uses a square wave oscillator, I'd reccomend the use of a blend/mix control, blending/mixing both dry and wet signals.
With a square wave oscillator you're only going to hear the two extremes of the wah sweep, so you loose (so to speak) a lot.

[DWBH]

I've found another 'modulated wah':http://www.members.shaw.ca/roma/wah-two.html (scroll down - running wah).
The wave produced is a sine wave, which produces a smoother sound.
The cool thing would be to have all sine waves, triangle waves and square waves in the same circuit - tremolo LFOs!!

[jacobyjd]

The cool thing would be to have all sine waves, triangle waves and square waves in the same circuit - tremolo LFOs!!

I was wondering about this--I know dano mentioned that you could use just about any LFO that would drive a vactrol...I immediately thought of some of the more versatile trem LFOs.

I think this circuit just made it to my 'build asap' list.

[AM]

Hey Dano,
I have a question regarding the schematic. I looked at a layout I had and there are a few different values from yours
(C1-C7- added Vr=100k). Is yours based on the reissue version?

Link to layout:
http://www.aronnelson.com/gallery/main.php/v/Cab42s-layouts/cil_wah.gif.html

[DWBH]

The cool thing would be to have all sine waves, triangle waves and square waves in the same circuit - tremolo LFOs!!

I think this circuit just made it to my 'build asap' list.

Hell yeah, it made to my build list as well. Next time I order parts I'll make sure I order parts for this one.

[dano12]

Not sure if you were kidding or not, but I always thought the Ooh Wah was just a sequencer changing the pot's resistance of one wah.

Yeah, I was talking about adding 8 pots to control the setting of one wah.

Hey Dano,
I have a question regarding the schematic. I looked at a layout I had and there are a few different values from yours
(C1-C7- added Vr=100k). Is yours based on the reissue version?

Link to layout:
http://www.aronnelson.com/gallery/main.php/v/Cab42s-layouts/cil_wah.gif.html

I swapped a few values to make it sound a bit better.

In other news, I finally got what puretube quoted about the "worm". The EHX Worm pedal does something similar: an LFO that controls four different circuits: phase, wah, etc. The new XO version looks super hot and it has an exp pedal input so you can bypass the lfo in favor of a foot controller. Genius!

Anyway, I think the ultimate rendition of this idea would be:

- a powerful and versatile LFO: sine, triangle, square, + programmable (maybe like the DSWF I did last year?)
- multiple filter circuits: like the EXH Worm--a wah, a vibrator, a phaser, etc.

That would kick some serious ass.

[DWBH]

I was trying to fetch the older version of the EHX Worm on Ebay, but the guy won't ship to Portugal
I'm very interested in the Worm schematic (http://www.diystompboxes.com/smfforum/index.php?topic=55068.msg593841#msg593841), so if anyone has it, please share it!

I wouldn't build a box with various filter circuits. Imagine you wanted different LFO rates/depths/whatever for, say, the vibrato and wah. You'd need different LFOs (crazy!, man!)
I'd rather have them in seperate boxes, but that's just my personal taste.

[oskar]

I tried the oscillator setup like I said above, but as before, I only get oscillation it I connect the LED to the output and input of the oscillator. Strange.

The rate LED? You need a series resistance to go with it or the LED will probably sink too much for the LFO to operate. It won't charge the cap up till switching level.

[DWBH]

I tried the oscillator setup like I said above, but as before, I only get oscillation it I connect the LED to the output and input of the oscillator. Strange.

The rate LED? You need a series resistance to go with it or the LED will probably sink too much for the LFO to operate. It won't charge the cap up till switching level.

Hummm.. ok, I'll try that.

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HOLY SH*T, I just say this article
http://www.beavisaudio.com/Projects/DSWF/


I knew about the Arduino thing, but I never thought such cool things could be done with it.

[kinski]

Hi all, thanks for the great info on this circuit!

Is there a verified layout or pcb of this?

It would be great to have the circuit so there is the standard colorsound wah (for fixed wah sounds), and then a switch to engage the LFO circuit.