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Crying time non madbean ( fixed sort of)

Started by Matt, June 02, 2013, 12:38:56 AM

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Matt

#30
Quote from: RobA on June 15, 2013, 05:09:41 PM
It couldn't hurt to check with a different power supply. But, I'd think that Boss has plenty of current available.

I went through your photos to see if I could see anything obvious that we have different. I couldn't see anything. But, some spots are hard to trace in the photo. Do you have a link to the schematic you worked from?
This should be it.  2 differences, I didn't use the ramp mod but I did use the stuck wah mod.  If I remember correctly its just a diode in parallel with the external rate led.
Matt

RobA

That looks to be what I have on my breadboard. I haven't got the stuck wah mod though. I'll have to look at that.
Affiliations: Music Unfolding (musicunfolding.com), software based effects and Rock•it Frog (rock.it-frog.com), DIY effects (coming soon).

RobA

Well, I did finally have to pull this off my breadboard with no success in causing it to tick. Before I did though I was able to put my new little oscilloscope to use and look at the LFO with various op amps in it. Based on that, I have one suggestion you might want to try. I think that you said you thought it was ticking at the top of brightness curve. If that's the case, this might help.

I noticed the top of the LFO trace is most distorted with the LM358 in it. The LM358 is good though because its input includes the negative rail. Lot's of other op amps latch up and flip to the positive rail while the input is too low. So, you need an op amp the can handle the negative rail and does better at the top of the curve. I've been looking at lots of LFO's lately and found that the TLC272 does the best job of hitting both those requirements of the op amps that I see commonly used in pedals.

I'm not sure that it'll help at all, but if you have a TLC272 or can put one in your next order, it's worth a try.
Affiliations: Music Unfolding (musicunfolding.com), software based effects and Rock•it Frog (rock.it-frog.com), DIY effects (coming soon).

Matt

Quote from: RobA on June 28, 2013, 12:29:58 PM
Well, I did finally have to pull this off my breadboard with no success in causing it to tick. Before I did though I was able to put my new little oscilloscope to use and look at the LFO with various op amps in it. Based on that, I have one suggestion you might want to try. I think that you said you thought it was ticking at the top of brightness curve. If that's the case, this might help.

I noticed the top of the LFO trace is most distorted with the LM358 in it. The LM358 is good though because its input includes the negative rail. Lot's of other op amps latch up and flip to the positive rail while the input is too low. So, you need an op amp the can handle the negative rail and does better at the top of the curve. I've been looking at lots of LFO's lately and found that the TLC272 does the best job of hitting both those requirements of the op amps that I see commonly used in pedals.

I'm not sure that it'll help at all, but if you have a TLC272 or can put one in your next order, it's worth a try.

I don't have one of those but I'll give it a try.

I tried a few things the other day.  I hooked up a 9v battery, still ticked.  I tried a voodoo lab 4x4, still ticked.  I tried a different 100uf cap for the power supply filter, no luck.  Then I breadboarded a buffer using a 2n5088 with a separate power supply.  The ticking went away but when I switched the pedal to bypass, I got a loud pop.  I switched it off and on a couple of times but the pop didn't go away. 

Matt

midwayfair

Quote from: Dc10 on July 03, 2013, 04:54:34 PMbut when I switched the pedal to bypass, I got a loud pop.  I switched it off and on a couple of times but the pop didn't go away. 

Did you use a pull-down resistor before the buffer? It's just like anything else with true bypass; it'll pop if you don't protect it.

Matt

Quote from: midwayfair on July 03, 2013, 04:56:35 PM
Quote from: Dc10 on July 03, 2013, 04:54:34 PMbut when I switched the pedal to bypass, I got a loud pop.  I switched it off and on a couple of times but the pop didn't go away. 

Did you use a pull-down resistor before the buffer? It's just like anything else with true bypass; it'll pop if you don't protect it.
. At first no because I wired the buffer without a footswitch.  I just breadboarded it and put an in and an out jack both of which had ground wires attached to them.  Then I wondered about needing a pull-down so I put a 1M at the input... No difference, still popped.

Also, I ended up putting the buffer in the pedal and running it with the existing supply and filtering.  It ticked as if the buffer wasn't even there.  But the popping disappeared.
Matt