UGLYFACE DUAL LFO WIRING ADVICE NEEDED (Duckarse maybe??)

[brokenstarguitar]

I need a little help with an Uglyface I'm building. I used the layout below but also added a second LFO. I put an on-off-on toggle to select between each lfo. Everything works good but I wired something wrong and Im not grasping it. When the Toggle is in the center (off) Both LFOs should be on via their power switches but both are off. How would I wire it to have the on-off-on toggle uglyface lfo - both lfos - aux lfo?

The toggle is wired with the common to lug 3 of the 7555, one end of each of the ldrs to the opposite lugs of the toggle, and the other end of the ldrs to pin 2 of the 7555.

[duck_arse]

urgh! I see only veroboard. have a stab at drawing out what you want to have built, and it may show you where you are, let's say, going wrong. and once you have a circuit, we can point and comment on "things".

rude qwestion - why two lfo's?

[blackieNYC]

Two LFOs - because it is awesome! About to box up a dual LFO Escobedo pwm. Square waves adding and subtracting, making a city skyline waveform, then softened with a series cap and a cap to ground. I used an op amp stage to mix the two LFOs, which would complicate your switch. How about mixing the two thru the - input of an op amp, and using depth controls on each LFO - controls that can take one down to zero? 
Once I heard my two LFOs blended into the pwm, I realized I would never turn them off. Matter of fact, in a knob-reduction exercise, I put the depth and speed controls inside. I don't expect to ever change them frankly. It's wild.
The uglyface is a similar sounding extreme device - crazy, really.  This is not a fuzz& chorus. You may find that adjusting the LFO speed is like...  Deciding which sunglasses the bikini model wears. Gotta have em, but do the subtleties matter?

[robthequiet]

Not too hard to imagine a two-pickup guitar switch logic, so you really would logically need an on-both-on. So how do they mix into the circuit in the middle (both) position according to your connections? A diagram might help here, as duck_ has suggested.

This could resemble a synthesizer CV wiring. The danger here is that if you have two LFOs pumping and their voltage adds up to the max, there would be no modulation, only a dimed CV. The test for this would be to roll LFO levels down to about 20% each and then increase one at a time to see if there is modulation.

Could be cool, like a sample-and-hold effect.

[digi2t]

Could be cool, like a sample-and-hold effect.

Darn!! Thanks for that reminder. I tried that, and it worked really well. I got side tracked with other projects though, and never got around to building it in. Might be something to do this weekend.

This is what I used for the sample/hold;

[duck_arse]

Not too hard to imagine a two-pickup guitar switch logic, so you really would logically need an on-both-on. So how do they mix into the circuit in the middle (both) position according to your connections? A diagram might help here, as duck_ has suggested.

nuh-uh! and yes. if you run two oscillators with a led each pointing at one ldr, THEN you could use on - off - on if you wired so ON one way shorted across one led, ON the other way shorted across the other led, and OFF was shorting no leds. both leds MUST HAVE seperate CLR, obviously.

lack of tikking not garanteed [sp?], either. but, once we get a diagram of intentions, we'll know how to proceed.

[late addition :] to clarify, I'm not asking why two lfo's, I'm asking why two lfo's. I understand the result of mixing of the two sigs, but the OP did not indicate which way he would use the seperate oscillators.

[brokenstarguitar]

What happened was, without thinking, I added the hole for the toggle but I dont need that option being I can control them individually but their Power switches. Any ideas as to what I can do with the "extra" toggle? I was thinking HP/LP filter but if theres an option to make this even crazier I'm definitely open to trying it

[GibsonGM]

Kill switch (mute button)    

[brokenstarguitar]

Only a toggle will fit. I'm trying to get the "weirdest" I can...... hmm?.....

[duck_arse]

well, why not add an enveloped rate-change (I can breadboard this faster than I can name the idea properly) to the lfo?

[edit :] wait a minute - isn't that what the 386 drives the led for? I should probably look at a circuit.

[brokenstarguitar]

I'll try to add pictures today. Sorry but I've been so busy. Both lfos are hooked to pins 2 and 3 of the 7555. Isn't their a way to modulate the volume or something with the auxiliary (2nd) lfo?

[duck_arse]

have you seen the circuit for the machette?

pin 5 is called "control voltage". you can pull it up towards supply, or down towards ground, to shove the frequency about some more. or run an lfo into it, probably via a cap. try hanging an ldr from pin 5 to ground, and bright/dark it, see if you can hear any change. it works more one way than the other because of the chip internals, I can't remember which is which tho.

[brokenstarguitar]

have you seen the circuit for the machette?

pin 5 is called "control voltage". you can pull it up towards supply, or down towards ground, to shove the frequency about some more. or run an lfo into it, probably via a cap. try hanging an ldr from pin 5 to ground, and bright/dark it, see if you can hear any change. it works more one way than the other because of the chip internals, I can't remember which is which tho.

I'm aware of the Machete but never took a good look at the schematic until now but it doesn't show the use of pin 5. Only difference I can see between the Machete and the layout above is the chip used for the lfo but it's wired the same. Between pin 2 and 3. It's late here so I'm going to try to string the ldr from pin 5 as you suggested and see what happens. I'll report back tomorrow and let you know how it goes. Thanks so much!

Btw, heres the link to the Machete build doc and schematic 

http://www.grindcustomsfx.com/product/gcfx-machette/

[brokenstarguitar]

I did what you said and it wasn't a good sound at all. I put one side of a ldr to pin 5 and the other to ground, light darker it but nothing usable. I then did the same with the ldr from the aux lfo, hoping there would be a different result but no. I then tried a bunch of different value caps with both and still no. I did get a weird unusable stutter with a .01uf cap though. Anything else you can recommend?

After digging a little on the net I think my best bet would be to redesign the lfo to have a sine wave/square wave toggle. What do you think?   

[duck_arse]

brokenstar - have you seen the mess in this thread? I can't make head or tail of it anymore, but there might be something there for you:
http://www.diystompboxes.com/smfforum/index.php?topic=108756.0

the reason I stopped fartarsing about with this circuit is the horrible sounds did my ears in. it's too piercing, man, like ooh.