'LIGHTWAH'

deadastronaut · February 14, 2013, 07:00:15 PM

whats the spec of the ldr?..should be 1M DARK..............beep..............................beep.........................................................

check the resistor value to the leds?.........shouldn't be dim with a standard yellow led.................beep...................................beep.....................................................

try other bright............were break....ing up...................beep..............led.....over..

andyhooper · February 15, 2013, 08:01:04 AM

Mr. deadastronaut, you have created yourself one weird and great circuit here. I got the footwah section working perfectly. Now...the LFO section works as well. I put a Red LED instead of the superbright yellow, which doesn't light up at all, yet with that red led the external LFO LED (I used a 3mm superbright white) flashes like a madman, so I sandwiched that white LED between the (non functional yet it serves it purpose in this case haha) red led and the LDR and the LFO section works just fine but is noisy. So here goes the question, if I don't get superbright yellows, what other superbright LEDs could I use and what resistor value should I use for that LED? Looking at the schem and the pcb I understand that the 100ohm resistor is for the yellow LED, am I right so far? The other thing is that I'm quite a noob with multimeters and voltages. Am I right also in saying that the resistor for the superbright blue (which I did get) is 4.7k? The LDRs I'm using are the ones that are about the size of the 5mm LEDs. They're not the little ones and not the really big ones. thanks in advance for any help you could give.

threepwood · March 24, 2013, 12:03:44 PM

Hey all,

I built the Lightwah circuit yesterday and fired it up this morning but I'm having a funny issue with it.

The LFO 'auto' section works perfectly but when I switch to the LDR 'manual' mode I have a problem. I get a nice loud signal but moving my hand towards the LDR has no effect. Rotating the sense knob affects the tone and LEDs but the external LDR just doesn't do anything. Considering that this is the main selling point (well to me anyway) I'm pretty miffed. I'm sure it's just a silly error on my part but I just can't work out out. I've checked my soldering and connections but everything looks fine.

I thought I may have a dodgy LDR so swapped it out for a fresh one but it didn't make any difference. Does anyone have any ideas? I'll post some photos as soon as I am able.

Thanks in advance!

deadastronaut · March 25, 2013, 06:27:49 AM

hmmm...

are your ldrs measuring 1M when dark...

and a few 'k' when lit..

threepwood · March 25, 2013, 11:07:56 AM

Hey Rob

I'll reply on here from now on rather than PM'ing you so that anyone else having this issue will benefit from any answers.

Yep LDR's are all the right value, which I guess is proven by the fact the auto wah side of the pedal works.

As mentioned in your PM to me I checked to see if I'd accidentally bridged the external LDR's solder pads but they look fine to me. Here are some photos that might shed some light (no pun intended) on the issue.

Thanks again.

and from the other side

deadastronaut · March 25, 2013, 11:16:19 AM

hi,

going by my eyes, that looks like a 470r resistor, not a 4.7k

on the bottom left just above Q2...

swap it out for a 4.7k and then try it..

Govmnt_Lacky · March 25, 2013, 11:23:14 AM

Looks like a 4-band resistor. Yellow-Purple-Red-Brown = 4.7K (1%)

Funny... didn't know thay made 1% resistors in 4 band

deadastronaut · March 25, 2013, 11:28:03 AM

hmmmm must be my bad eyesight then..

threepwood · March 25, 2013, 12:04:12 PM

Govmnt_Lacky is right, it's a 4.7K.

Darn, I got excited then!

shay1510 · April 23, 2013, 01:46:14 PM

Hey guys,
Built this pedal and it's great. However, small problem occurs:
The effect controlled by the rate/speed knob is too fast, even when the pot is fully rotated. (the led blinks every 0.5-0.7 sec at slowest speed).

checked the pot value and the resistors values.

Any thought?

midwayfair · April 23, 2013, 01:53:29 PM

Quote from: shay1510 on April 23, 2013, 01:46:14 PM
Hey guys,
Built this pedal and it's great. However, small problem occurs:
The effect controlled by the rate/speed knob is too fast, even when the pot is fully rotated. (the led blinks every 0.5-0.7 sec at slowest speed).

checked the pot value and the resistors values.

Any thought?

You want it to oscillate slower?

C8, that 10uF cap at pin 5 of the LFO, is the timer cap. 22uF will make the sweep a couple seconds. Apparently if you go to 47uF, it'll be a 15 second sweep (http://www.madbeanpedals.com/forum/index.php?topic=6055.msg77086#msg77086). How slow do you want?

Be sure to use a reverse log for the speed pot if you do this.

shay1510 · April 23, 2013, 05:40:12 PM

apparently I've used a 1uF cap.
Midwayfair, thanks for the answer, I'll try some different values till I get it right.

mma_rub · July 21, 2013, 02:08:01 PM

Hi. Excuse for my English, I write through the translator. Tell, whether it is possible to connect LightWah and Optochopto as it was represented by me? I increased the entrance condenser that it was possible to use a bass guitar. I thought to make switch to change entrance capacity

stallik · November 09, 2013, 02:35:02 PM

Thanks Rob for another wicked circuit.
Just put together my first lightwah and everything appears to be functioning but I'd like a little clarification on a couple of operational points just to be sure.
Is it intended that the foot LDR works off ambient light, Is there meant to be a small footwah effect when in LFO mode and is it normal for there to be a slight distortion of the lower frequencies in both modes?
My build is not currently boxed
Thanks

deadastronaut · November 09, 2013, 02:53:17 PM

Quote from: stallik on November 09, 2013, 02:35:02 PM
Thanks Rob for another wicked circuit.
Just put together my first lightwah and everything appears to be functioning but I'd like a little clarification on a couple of operational points just to be sure.
Is it intended that the foot LDR works off ambient light, Is there meant to be a small footwah effect when in LFO mode and is it normal for there to be a slight distortion of the lower frequencies in both modes?
My build is not currently boxed
Thanks

in lfo mode it should be just lfo.. ( are your led/ldr's in shrink tube?...isolated )

the foot ldr works off the ambient light yes, adjust the sense to it....more light the better though...(i toyed with the idea of having another dc socket with a plug in led on a bendy wire to hang over it..)

never noticed distortion...hmmmm..

stallik · November 09, 2013, 03:59:07 PM

Thanks Rob, yes they're shrink tubed but I used blue LEDs as the yellows I got in were flashers! Must have a short or something leaking something into the LFO section. Mind you, it's a neat effect - changing the overall tone as the LFO works. Probably what's giving me the distortion too.
Let you know

stallik · November 09, 2013, 06:12:47 PM

Ho hum. Just taken a good look over my board looking for shorts etc. Only thing I found was a little wisp of fibre. Maybe cotton or something like that. Brushed it off and found nothing else. Yet the distortion is gone and there's no bleed over to the LFO anymore. Probably means I've got a weak connection somewhere but for now, I'm just enjoying another great pedal.
Thanks again

stallik · November 14, 2013, 10:25:28 AM

Boxed up. Used a DDT switch for foot wah/LFO to switch one of the panel LEDs off

And the guts. Will try to tidy it up when I've settled on the led switching

deadastronaut · November 14, 2013, 11:14:54 AM

^ looks great kevin, ...

love the spacey themes you do..

stallik · November 14, 2013, 11:50:53 AM

Thanks Rob, got a GU10 spotlight shining down on my board. Casts a sharp shadow of my foot, more blurred from hand level. Great fun strumming in the beam of light and getting an auto wah thing going. Drumming my fingers in the air gives a really rapid wah and I can get all kinds of effects going using fingers, hands and feet.

I must look bl**dy stupid!

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