is there any auto wah without LDR/LED thing?

[col]

The DOD one with the LM13600 (I used a 13700) works very well as does the nurse quacky. There are simpler ones around that don't respond to your playing but vary the tone wrt an oscillator rather like a tremelo would vary the volume. One of Penfold's early books has one that uses a 555 and the one I built worked. I also built one that had a minimal parts count but can't remember where I got the schematic from, I think it used an op-amp oscillator. Both used a FET to vary the tone.

[vendettav]

hmm how would you go with wiring a FET as a tone varier?

also can you get me the schematic for that 555 one?? interesting as how it looks

[Paul Marossy]

In my DOD FX17 I figured out that swapping the output from the LM13600 changed from bandpass to lowpass, and if I remember right, taking from the bandpass output, and removing the feedback resistor in that section resulted in the high-pass mode. I just hardwired it in lowpass (removed the resistor and soldered it to the trace side of the board). So you can basically get all 3 from that circuit with a bit of switching trickery.

That's clever. Getting more switches on that thing must be something of a challenge. Those pedals are a PITA to work on as it is... 

[twabelljr]

http://hammer.ampage.org/?cmd=lt&xid=&fid=&ex=&pg=7

Here is a Penfold Autowah.

[deadastronaut]

i'd stay away from lfo's that use a 555/cmos 555...

i built an auto wah using a 555 for the lfo, all was fine on breadboard, but when i finally got it on pcb it ticked...tick....tick.....tick.....

i'd use an opamp for lfo...i'm working on it now...another thing i find with led/ldr lfo's is the led is on a bit longer than off...with lots of lfo's ive tried..

so they all need a bit of tweaking imo...

[vendettav]

nice. i actually was thinking. how do you hook the LFO to a circuit??? with it controlling the brightness of the LED and a LDR instead of a pot? that's the only thing missing for me to actually try and dive into LFOs

[deadastronaut]

instead of the wah pot...just swap it for an ldr...

have your lfo/led facing the ldr.....heres mine.... whooo..embedding at last..

its basically a morley wah...with an lfo..

heres the current thread on it...

http://www.diystompboxes.com/smfforum/index.php?topic=88582.0

edit: ive been trying to get one half of an opamp to do the lfo, and the other half for the wah....

[vendettav]

that's a lovely design Rob. especially with the hand on the board for the effect.. reminds me of Zvex probe idea
http://4.bp.blogspot.com/_y4AYtND8Hz8/R-D1JQQcF9I/AAAAAAAAAKI/upWnOEC87_g/s1600/vsex_probe.jpg
whats the IC in there btw?

and this is the wah part http://1.bp.blogspot.com/_y4AYtND8Hz8/R-D1JgQcF-I/AAAAAAAAAKQ/cQHq4BwyzCI/s1600-h/colorsound_wah_vsex_mods.jpg so i give if i get a ldr and hok it up there I can hook it up with any LFO i come up with? tho i'd actually go with morley as well i guess

but hey! is there a schematic available for the pulsewah? 

[deadastronaut]

cheers ,. yeah i had the ldr working backwards, it opened the wah when dark...

i use lm358n for the lfo now...and a butchered 'phOser' wah... one half of it anyway....(the top vid is the morley wah though...

bit better wah than the colorsound...imo.

there is a scheme for it on the thread link....

or the pcb i made for a version here...verified. it has the pulse..and a fixed wah option (toggle switch)too...

http://www.aronnelson.com/gallery/main.php/v/chickpea/render.gif.html

[vendettav]

lookin good Rob, I'll make sure i bookmark this thread for the future