madbeanpedals::forum

Projects => Tech Help - Projects Page => Topic started by: musovern on March 05, 2012, 12:06:17 AM

Title: EgoDrive LED Clip mod
Post by: musovern on March 05, 2012, 12:06:17 AM
My LED Clipping mod doesn't seem to work for me, Have tryed a few different types of  led's . Had the gain and tone on full can not here any change in the sound and still no luck.

Any thoughts on a led type and spec. mine current one is a 5mm RED CLR 12,000mcd 2.3v  which doesn't work either.

Any suggestions very welcome.

Great sounding pedal other than the clip mod.
Title: Re: EgoDrive LED Clip mod
Post by: pryde on March 05, 2012, 01:57:23 AM
It seems like everything is wired up correctly in the picture. Did you try to re-flow the ground to R3 just to be sure? It is a tight area so maybe a solder bridge or something?

Do the LEDs light up at all when playing?

BTW: I used 5mm water clear high-brightness in mine and there is a difference at higher gain vs normal clipping. Good luck
Title: Re: EgoDrive LED Clip mod
Post by: mgwhit on March 05, 2012, 03:12:51 AM
Which pad do you have D4 soldered to?  I can barely see the pads on your photo as they're obscured by the LED and the wire, but I feel like I see solder in the square pad and the round pad appears (through the LED!) empty.  Apologies if I'm seeing it wrong.
Title: Re: EgoDrive LED Clip mod
Post by: musovern on March 05, 2012, 04:46:30 AM
I did a Re solder  didn't make any difference. Led's do not light up even with all knobs on full.  :( Would of be nice to here the difference in the clipping.

Led 1 (+) to square of D3 and LED 2 (-) to the round of D4

cheers
Title: Re: EgoDrive LED Clip mod
Post by: madbean on March 05, 2012, 12:42:56 PM
It must be LED type. I just had a look and I believe mine were from Tayda. They list their water clear high brightness forward voltage at 3.2v or so and the MCD at 16 - 20k (for the white). Do you have any others you can try? I might have some more of those particular LEDs left, so I could always drop a couple in the mail to you.
Title: Re: EgoDrive LED Clip mod
Post by: oldhousescott on March 05, 2012, 01:59:52 PM
Gain at max through the first stage is about 500. Even if your LED had a forward drop of 3.5v, it would only take a 7mV input signal before the LED started to clip. As noted, the forward drop for most LEDs is in the 2-3v range. Note, too, that the opamp will start to clip at just slightly above that, maybe around 4 to 4.2v on a standard 9v supply. It's possible the LED clipping is getting lost in the opamp clipping for certain high-threshold LEDs. This is an instance where an 18v supply would be beneficial.
Title: Re: EgoDrive LED Clip mod
Post by: pryde on March 05, 2012, 09:49:11 PM
Quote from: madbean on March 05, 2012, 12:42:56 PM
It must be LED type. I just had a look and I believe mine were from Tayda. They list their water clear high brightness forward voltage at 3.2v or so and the MCD at 16 - 20k (for the white). Do you have any others you can try? I might have some more of those particular LEDs left, so I could always drop a couple in the mail to you.

I picked mine up at a local Radio Shack and they work fine in my pedal. Here they are:
http://www.radioshack.com/product/index.jsp?productId=3060980&filterName=Brand&filterValue=RadioShack

Title: Re: EgoDrive LED Clip mod
Post by: musovern on March 05, 2012, 10:22:55 PM
Thanks for the help guys,
I have tryed again. This time not with a battery but a 9v power supply. And now the LED's light up, Not very much change in sound so it is a Led problem.

do you think this led would be ok.?
5mm 20,000mcd WHITE LED 3.4V

My current one is a 5mm RED CLR 12,000mcd 2.3v.

Kind regards

Vernon
Title: Re: EgoDrive LED Clip mod
Post by: pryde on March 06, 2012, 02:04:14 AM
Best thing to do is try them out. The 3.4 voltage is similar to the radio-shack ones I use so they may work for you.

I will say that the difference in clipping sound in my build is by no means "dramatic" so I don't know how much should be expected between stock and LEDs? To me I actually prefer the stock clipping anyway.
Title: Re: EgoDrive LED Clip mod
Post by: mgwhit on March 06, 2012, 02:26:26 AM
Quote from: musovern on March 05, 2012, 10:22:55 PM
do you think this led would be ok.?
5mm 20,000mcd WHITE LED 3.4V

My current one is a 5mm RED CLR 12,000mcd 2.3v.

If you're having trouble getting a 2.3v LED to clip, I would think that the 3.4v would just be even less likely to work.  (Edit: I just read Bean's post saying he used 3.2v LEDs -- go figure....)  Still, socket and test!  I gotta admit that since these LED's are connected to VB instead of ground there may be things going on that I don't understand.