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Autowah, plus fixed wah, same enclosure, footswitchable

Started by rmfroyd, May 18, 2016, 12:51:22 PM

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rmfroyd

I have been searching with the google machine most of the morning and have come up empty.

Here is what I would like to do:

Autowah and Fixed(cocked)wah in same enclosure.

1 footswitch to turn Autowah on or off, wLED
1 footswitch that turns off autowah, turns on Fixed wah, for ripping cocked wah like solo.  also w LED

I found plenty of diagrams on how to wire up to circuits with the ability to blend together, but I haven't been able to find any where you can turn one off and one on with one footswitch yet.

Thanks in advance for your help.

matmosphere

So you want one switch top be a matter on/off and one that switches between the effects? Or does the auto wah have to be the one that turns on and off every time you hit the first switch?

rmfroyd

Yes, exactly that.  One master and one to switch between the FX.  Thanks, I knew there was an easier way of wording it.

matmosphere

Do you want a matter led with the led for the selected effect always on, or do you want the led for the selected effect to turn on when the main switch is hit?

I'll try to draw you a diagram a little later this morning.

m-Kresol

this should do the trick. I used it on my No-mojo fuzz to switch on an off and the second switch to toggle between the two fuzzes.

I build pedals to hide my lousy playing.

My projects are labeled Quantum Effects. My shared OSH park projects: https://oshpark.com/profiles/m-Kresol
My build docs and tutorials


matmosphere


diablochris6

Just throwing this out there...

You might be able to combine the autowah and cocked wah idea into one circuit board. I'm thinking about the vactrol-based autowahs. If you were able to disconnect the LED from the envelope follower section and connected it to a voltage source (maybe with a pot in series to control LED brightness/filter frequency), you would only need one PCB and maybe a smaller box.
Build guides of my original designs and modifications here

midwayfair

No need for extra circuitry depending on the effect.

Kraken's an easy project to do this with. (The MIII would be complicated.)

http://www.madbeanpedals.com/projects/Kraken/Kraken.pdf

Remove the base of Q2 from the circuit board. Run a wire from it to the center of a footswitch. An outside lug of that pole goes back to the base's hole in the PCB. In one position, we have the envelope input as normal.

Let's examine our envelope. The diodes are oriented so that only negative swings of the waveform pass through D1. Q2's base is held up to Vb via the decay pot. When the negative voltage swing passes D1, it drives the base of Q2 down to ground. This then changes the voltage on the collector and alters the bias of the chip.

So if we're going to manually control this, we need a way to manually alter that bias.

Fortunately, there's an extremely convenient way to do this: R17. Remove it and replace it with lugs 1 and 3 of a 100K pot. This will keep the constant 100K resistance when the pot's not in use. The wiper then goes to the other side of your bypass switch to be connected to the base of Q2 in the other switch position.

When you turn the pot, it'll alter the bias and change the sound of the stuck wah. When the wiper is all the way at ground, it's bright, when it's at Vb it's dark.

Break down your favorite auto-wah to locate the same types of reference points and you can do this with any envelope filter.

rmfroyd

Damn,  I think I actually followed that.

So I can use a SPDT latching footswitch for the stuck wah switch correct?

I might try to draw something up and post it here tomorrow to make sure I am following along correctly.  Thanks for the info.

midwayfair

Quote from: rmfroyd on May 18, 2016, 07:37:40 PM
So I can use a SPDT latching footswitch for the stuck wah switch correct?

Sure, unless you need an LED.

rmfroyd

Finally got it wired up and tested.   Works great, thanks a ton for the suggestions! All I have to do is make the enclosure and wire up the leds.



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Orbis_Ignis


rmfroyd

Well, I thought I had it working.  When the filter switch is set to the low position everything works perfect when the manual wah side is on.  When I switch it to the high position on the switch the manual side develops a high pitched dead spot at about the 90% mark on the sweep, then it goes away on full sweep. 

Anyone have any ideas?

rmfroyd