'LIGHTWAH'

[haveyouseenhim]

I'm not using a pot. I plan on printing a color gradient onto a transparency to control the light to the ldr.

[deadastronaut]

cool.

[Jdansti]

I'm not using a pot. I plan on printing a color gradient onto a transparency to control the light to the ldr.

It will be interesting to see how the colors work out. The LDR responses more to certain wavelengths, your light source only emits certain wavelengths, and the colors on your transparency only transmit certain wavelengths. You might see a nonlinear response as you sweep the transparency back and forth.

You might consider using a black gradient such one of these if the color doesn't work out for you.

[haveyouseenhim]

@ john

Oh, I didn't mean 'color'... I meant black. I'm probably going to use the ones you just posted.(thanks  ) and if that doesn't work I'll use the v shaped slit method. Having the gradual v shaped slit in an opaque sheet of plastic will slowly allow more light to hit the ldr as its passed between.

[haveyouseenhim]

Wasn't this originally a vero layout?  I cant find it if so!

And I'm a bit confused on this perf layout (i really wanna build this and really hate perf so I'm hoping there's a vero!) So what kind of LDR's work best here?  where did you get yours?  I've had bad luck building effects with homemade optocouplers, I always just like to pay the extra dough for the vactrols or the nsl32's.  But if you know the exact LDR you used that would be awesome!!!

Thanks for this awesome project... agian where can I find the vero layout?

Claytus

I think you may have confused this for my frankenstien pulse wah. i till haven't debugged and verified the vero layout.

[scuzzphut]

Just finished assembly and the circuit is working - but the effect is not very pronounced at all - in wah or LFO mode.

I suspect it's to do with the combination of LDR and LEDs.

The LDRs I have are as follows :

Resistance at 10 lux = 50 -100k Ohms Dark resistance = 20 M Ohms Rise time 20ms Decay time 30ms

I have them heatshrinked in with 5mm ultrabright blues (both).

Any hints as to where I should start adjusting other components to calibrate ?  Or should I swap out the LDRs ??


(Edit - I see that Rob's LDRs are 5k-1M , quite a difference, dang - is there any hope for the LDRs I have??)

[puretube]

LDRs are quite color-sensitive... (the ones I know react the best @ 550-600nm)
LEDs do come in other colors than blue...

[haveyouseenhim]

I'm sitting here working on the lightwah and listening to the Wooden Shjips station on Pandora and this song comes on:

What a coincidence.

[Tony Forestiere]

LDRs are quite color-sensitive... (the ones I know react the best @ 550-600nm)
LEDs do come in other colors than blue...

Good call, PT. Additive color theory suggests approximately:
400 to 500nm = Blue
500 to 600nm = Green
700 to 700nm = Red

Although suggested in reality:
450 to 495nm = Blue
495 to 570nm = Green
620 to 750nm = Red

Try a Green?

http://en.wikipedia.org/wiki/Visible_spectrum

*link added for posterity*

[deadastronaut]

i seem to recall mark hammer posting a chart in which ldrs 'liked'' yellows

when i created this on breadboard yellow was fine for the lfo, and blue was fine for the  foot wah.

[scuzzphut]

Thanks guys - I found an old LDR with a better range that improves the actual footwah detector. Trouble is that it's 13mm in diameter so it's not going to look good on the box !  Will keep experimenting.

[haveyouseenhim]

Well, I'm stumped. I built this from the pdf and I'm getting no lfo. The lfo led is full brightness. Halp!

Need some pin voltages?

[scuzzphut]

I had the same thing when I built mine, HYSH.

Turns out it was a short between pins 2 and 3 of the LFO IC. Well worth checking your voltages and if any seem to be identical, check for shorts.

[haveyouseenhim]

1. 6.94
2. 6.94
3. 6.84
4. 0.2 mv
5. 6.92
6. 6.92
7. 6.92
8. 13.6

ic1
1. 6.74
2. 6.74
3.6.43
4. 0.1 mv
.
.
.
8. 13.56

[midwayfair]

8. 13.6

ic1


8. 13.56

Buh? From a 9v power supply?

[haveyouseenhim]

Its a zoom walwart. It says 9v 300ma   but with no load it reads 15.3v.... do you think that's my problem

edit     nvm   I just tested it with my regulated 9v supply and got the same result

[scuzzphut]

IC2 is the one in question.

Have you checked for shorts between pins 1 and 2. Between pins 5 and 6 ?

[haveyouseenhim]

No shorts anywhere. I went over the whole board with my flux pick and did a visual inspection then tested with my meter. I'm starting to lose hope. I may just do a total rebuild. Etch a new board. New parts, new everything

[Jdansti]

Edited due to erroneous information.     

[haveyouseenhim]

You've probably already done all of this, but:

Check LFO:
Resistor values 
C2, C9, Q2 orientation
Pot for proper operation

What layout are you talking about? the layout I'm using has no c9 and the c2 is a non-polarized film cap.    this is the layout i'm using:
http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=45818