'LIGHTWAH'

[mattthegamer463]

cool.

Deadastronaut,

I still haven't gotten my LFO-less circuit working, what are the light/dark resistances of the LDRs you are using?  I think that could be part of my issue.

Also, are you 100% confident that this latest schematic is perfect?  If it is I am moving forward on the board order.  Once I get them and show they are working I'm sure people will want to buy the remaining boards from the batch.  I have to order in batches of 10.

[deadastronaut]

 they are 1M - ?..cant remember off hand...but definately 1M.....

your best bet is to check the schematic alongside the layout i did...as that works perfectly for sure!...just to be safe!. laborious i know, but it has to be right!...


is the wah working ok..is the light sensor part getting brighter as you cover the ldr?...

turn the sensor pot so the led is just off....then when you cover the ldr it should gradualy be on...

heres the sections of it if it helps ya ok...

[mattthegamer463]

Thanks, I'll inspect further when I get home.  I seem to recall the LEDs getting dimmer when I expose it to less light, maybe my LDRs operate backwards?  I don't know if those exist or not.

[mattthegamer463]

Well this thing still isn't working.  I've gone over it a couple times, still can't find the issue.  I have to crank my amp to max just to hear anything out of the circuit, and when I do it just sounds clean.  The voltage on both sides of the LDR is 0V.  The +, - and output of  the op amp is 4.5V as it should be.  Doesn't appear to be anything wrong with that. No signal is apparent on either input of the op-amp.  Something is going wrong with the caps and resistors.

[JOHNO]

cool.

Deadastronaut,

I still haven't gotten my LFO-less circuit working, what are the light/dark resistances of the LDRs you are using?  I think that could be part of my issue.

Also, are you 100% confident that this latest schematic is perfect?  If it is I am moving forward on the board order.  Once I get them and show they are working I'm sure people will want to buy the remaining boards from the batch.  I have to order in batches of 10.

I'm confident that the new schem is 100% correct.

[mattthegamer463]

cool.

Deadastronaut,

I still haven't gotten my LFO-less circuit working, what are the light/dark resistances of the LDRs you are using?  I think that could be part of my issue.

Also, are you 100% confident that this latest schematic is perfect?  If it is I am moving forward on the board order.  Once I get them and show they are working I'm sure people will want to buy the remaining boards from the batch.  I have to order in batches of 10.

I'm confident that the new schem is 100% correct.

Thanks.  Sounds like we're all set for the board order then.  Still can't figure out why my breadboard version won't work though...

EDIT

I switched out my op amp for a new one just to try, now the circuit sounds clean, but then when I put light to the wah LDR, there is no audible change until suddenly, with enough light, the output cuts off alltogether.  Very strange.

[vendettav]

you sure about your tranny pinout?

[JOHNO]

There is still a mistake in the schem. Q1 the ground connection should be between the emmiter and the ldr,not the ldr and base as the schem shows. I've got it on the bb minus the lfo and it is working fine once the ground is correct. I used standard leds and it is lacking some range but the high brightness leds should fix that. Also if you make it with out the lfo the external led is not really needed, just wave your hand over the foot ldr and set the sensitivity pot till your happy. Killer @#$%ing circuit Mr Rob. No more worn out pots.

[deadastronaut]

hi johno: gotcha..ammended.. ok.

like this?....above!..^  cheers..

http://www.diystompboxes.com/smfforum/index.php?topic=88582.msg794874#msg794874

[JOHNO]

Yep, that it should be good to go now.

[mattthegamer463]

I've amended the issues as well. 

One thing I've noticed;  on the Morley wah, the 3.3k is after a 10k volume pot, but here it goes straight to ground.  Seems like that would be killing a lot of signal amplitude doesn't it?

[Gurner]

I've amended the issues as well.  

One thing I've noticed;  on the Morley wah, the 3.3k is after a 10k volume pot, but here it goes straight to ground.  Seems like that would be killing a lot of signal amplitude doesn't it?

Have you a link to the morley schem you are referring to?

I touched upon this particular area a couple of pages ago...

"I'd be inclined to dispense with R6 & just put your output pot in its place (use something like a 5k pot)...or you could just keep your 100k , in place of R6 but change the cap value to something like 50nf. Not exactly sure what purpose R7 is serving on the original Morley Wah cct (http://www.morleypedals.com/clwes.pdf to my eyes it  looks like some form of output short cct protection).....it's presently acting as a potential divider in your implementation (which isn't R7 in Morley's cct's intended purpose for sure), so if moving the pot to R6's location just attach R7 between the pot wiper & the output jack. (even if you're not gonna move the pot to R6, R7 would be better on the output lug of your pot)

One component saved (R6) ...& possibly R7 if you're confident you won't short the output to ground at some stage ....let loose the pigeons!"

In the present lightwah schem, R7 is acting as a potential divider in conjunction with the output pot (losing about 7% of the overall output signal)...I believe R7s purpose is more to protect the opamp against shorts on the output...therefore I reckon R7 would be better served between the wiper of the pot and the output jack

[mattthegamer463]

I've amended the issues as well.  

One thing I've noticed;  on the Morley wah, the 3.3k is after a 10k volume pot, but here it goes straight to ground.  Seems like that would be killing a lot of signal amplitude doesn't it?

Have you a link to the morley schem you are referring to?

I touched upon this particular area a couple of pages ago...

"I'd be inclined to dispense with R6 & just put your output pot in its place (use something like a 5k pot)...or you could just keep your 100k , in place of R6 but change the cap value to something like 50nf. Not exactly sure what purpose R7 is serving on the original Morley Wah cct (http://www.morleypedals.com/clwes.pdf to my eyes it  looks like some form of output short cct protection).....it's presently acting as a potential divider in your implementation (which isn't R7 in Morley's cct's intended purpose for sure), so if moving the pot to R6's location just attach R7 between the pot wiper & the output jack. (even if you're not gonna move the pot to R6, R7 would be better on the output lug of your pot)

One component saved (R6) ...& possibly R7 if you're confident you won't short the output to ground at some stage ....let loose the pigeons!"

In the present lightwah schem, R7 is acting as a potential divider in conjunction with the output pot (losing about 7% of the overall output signal)...I believe R7s purpose is more to protect the opamp against shorts on the output...therefore I reckon R7 would be better served between the wiper of the pot and the output jack

This was the one I was looking at.  Theres a lot of them out there.

http://www.morleypedals.com/pwa.pdf

It just seemed a little odd to me.  Protecting the op-amp makes sense though.  I just still really can't figure out why my breadboard build is failing so badly...  I simulated the schematic earlier today in the form I have it in and it works fine, you can clearly see hump of the filter moving back and forth.  I think my LDRs are not adequate for whatever reason.  In simulation I tried 1M and 100k LDRs, from min light producing 100k and max light producing 500 ohms, and it worked fine at all values and in reasonable frequency ranges.  I also tried 1M simulated LDRs and the hump extended a bit lower in the frequency spectrum but still should work 100% of the time.  I'm going to try with a pot today, no question that that should work.

[Gurner]

This was the one I was looking at.  Theres a lot of them out there.

http://www.morleypedals.com/pwa.pdf

That one makes much more sense (& has R7 where I reckon it should go...not sure why they have a 10k pot *and* 3.3k resistor on the output though...that was one of my other observations, just lose the 3.3k altogether & put the pot there), I'd not seen your linked version & had previously reckoned this was the one folks were referencing...

http://www.morleypedals.com/clwes.pdf

[deadastronaut]

@gurner, yep thats the one (classic wah)....theres plenty of volume on it though...way over unity.

i changed the cap on the bottom of the 't' on the right...just sounded better IMO...

[ogroto]

This is amazing... great work deadast

Any chance of guts pic?
Thanks 

[BoxOfSnoo]

hi johno: gotcha..ammended.. ok.

like this?....above!..^  cheers..

http://www.diystompboxes.com/smfforum/index.php?topic=88582.msg794874#msg794874

Now you put the short back in between R11 and C7  Time for some file naming conventions? 

[deadastronaut]

^oh @#$% yeah....ok...

sorted!....

[nocentelli]

^oh @#$% yeah....ok...

sorted!....

I'm guessing the 470k pot should be labelled "speed", not sensitivity?

[deadastronaut]

yep!...