Earthquaker White Light Overdrive

[jwroper]

This one looks cool - be good to see how this actually differs from the DIST+ - http://www.joespedals.com/acatalog/copy_of_Earthquaker_White_Light_Overdrive.html

[IvIark]

Yes this is in the queue

[bmossma]

Any update on the White Light?  If someone can find a schematic I'll try and draw up a vero for it!  

[johnk]

I drew one up and built it so it's verified:





here's the vero:

[bmossma]

Awesome John!  Do you have a schematic availiable?  Thanks!

[johnk]

[atomicwombat]

has anyone else built and verified this one? I built it, and I get a volume drop with horrible squeal and oscillation at the top of the drive pots sweep. too bad, because it sounds great right up to that point. any info or ideas here would be appreciated. thanks

[johnk]

atomicwombat wrote

has anyone else built and verified this one? I built it, and I get a volume drop with horrible squeal and oscillation at the top of the drive pots sweep. too bad, because it sounds great right up to that point. any info or ideas here would be appreciated. thanks

IMO, you must have an error in your build since mine works perfectly.
as a rule of thumb, if verified one works, then they all will work.

[atomicwombat]

thanks for the quick reply john. this one has me stumped. I was thinking the same thing, that I must've made an error somewhere. I looked it over the best I could and didn't see anything, so I figured that I would just build another. this time I checked every components value with my meter. every cap, every resistor, and I ended up with the same result. it sounds great, right up to the end, and at the top of the drive pots sweep it goes into oscillation. I'm totally sure that my build matches the layout 100%, so I don't know what to think. I remember reading the fsb thread on this, and I think someone was having this same problem, but I thought it was fixed. maybe I've got a bad batch of lm833's? I tried a few in the circuit, and they all had the same result. I noticed in the picture you posted of your build that you have a resistor socketed, was there a reason for that? thanks

[atomicwombat]

john- I was looking at your pic of the board. is there an electrolytic cap missing from the layout? it looks like you have 4 on your board, but there's only 3 on the layout. you have one towards the top, right under the toggle switch. could that be the culprit?

[johnk]

that's just a 1u electro in place of the 1u ceramic on the layout.

[atomicwombat]

okay. it looks like its sitting right next to a ceramic to me. I've looked at it a dozen times, and I keep seeing 9 caps on the schematic/layout, but 10 on your board. am I crazy, or just missing something?

[Heath]

I see the same thing, Wombat.

[johnk]

I think that it's just an extra 100n to ground on the 9V rail.

[Sven]

Hello,

i built it and i have the same problems. I have tried different ICs, but still had the vd and oscillation.

best regards
Sven

[rocket88]

there does look to be an extra cap to the right of the 1uF electrolytic top middle of the board. but, if johnk built it then that's the layout he used, so it should work. not sure why it's not working

[atomicwombat]

I've built this one twice now, tried various ic's, socketed the cap and resistor on the drive pot and tried a few different values, pretty much tried everything I could think of to get it working right, but no luck. no matter what I've tried, it gets wonky as the pots are maxed. volume drop, oscillation, and high pitched whine. on the lower settings it works fine, but I've seen videos where all the controls are maxed out, so it should sound good turned up all the way. I'm sure my board matches the layout 100%, so I don't know what to think. its odd that johns works but Sven and I both had issues. I'm curious to see what result others have with this one.

[Jopn]

Looking at the schematic, the 100p should be connecting pins 1 and 2 of the opamp.  In the layout it's connected to pin 2, but then runs off to drive 2 instead of opamp pin 1.  Looking at John K's photo, it looks like he has it correctly going from pin 1 to 2.

Try making that adjustment and report back.

[johnk]

Jopn wrote

Looking at the schematic, the 100p should be connecting pins 1 and 2 of the opamp.  In the layout it's connected to pin 2, but then runs off to drive 2 instead of opamp pin 1.  Looking at John K's photo, it looks like he has it correctly going from pin 1 to 2.

Try making that adjustment and report back.

thanks for catching that. vero is updated.

[Sven]

thanks jopn,
that was the mistake. No issues anymore with this one.