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I may redo the buffer anyway. fixing this problem may have brought on another, I think. I need to dismantle it and revert the changes to make sure I'm not imagining things.

wow.... just, wow.

I undid all the changes I brought to the circuit, and it's still "fixed"-sounding. yeah, time to move on to other things I think.

oh, well, bummer. But that's how designing stuff is, I'd imagine.

haha ya well did you ever measure the dc output of the second stage or any of the other things from the previous post? take a break for today but i still feel that will be key to finding the real problem.


bonstjon

yeah, it fluctuated between 4.57 and 4.6v if I remember correctly. it doesnt matter anymore though. the cap fixed it seemingly.

my other problem is unreleated, and maybe always existed with this build. I can't get choppy LFO on it compared to my really old design (I just did a side by side). the faster you turn it, the more it smoothes out and you lose detail. I dont think I noticed this before (or never did a side by side so didnt realize the difference). anyways it means I need to revisit the whole LDR section. maybe find different quicker LDRs, though the ones I'm using are specced fast enough (at least in the datasheet).

ya i guess i would just be interested to see why it happens without that cap. to me all it did was put a LPF on the second stage which fyi will be around 10kHz with the output gain at max. Not that 10kHz probably matters with guitar but on the schem you linked it will dime at a much higher frequency since they use a lower valued pot.

If the values for the PWM/LED setup you poster are what your using then maybe to get choppier tremolo also remove that cap on the pwm. It makes a LPF with all those resistors with a cut off maybe around 1 Hz so for sure the LED is not receiving any rapidly changing signal at all. Just watch the voltage across the LED on a scope. im not sure what the 100k and 220 k are there for but you should be able to out 1 resistor and the led in series to ground from the PWM out. If it is fastish (anything like 1Khz or more) i would not even bother trying to smooth the PWM because no LDR can track that fast, in effect doing the filtering for you. also make teh series resistor a trim pot and you have some built in calibration. (:

i read the last few pages and then my brain exploded. i have no idea how i'm still typing

Well the cap near the LDR isn't really set up for a filter, since there's no series resistor between it and PWM output. Anyways, when I popped the cap out the choppiness didn't change much (a little). Can't remember exaclty why I had it there. The 220k and 100k are there to pull the PWM voltage range to what the LED needs.

Anyways, when I have time, I'll just cut the PWM trace loose and externalize the buffer/ldr circuit on a small breadboard. Like hell am I rebreadboarding the digital stuff. Code changes might also be needed. I do linear interpolation between VCA "samples" and I'm wondering if it doesn't blur details too much at higher speeds.

when is this compound gonna surface/?//

bugzaney wrote:when is this compound gonna surface/?//

the compound needs to be redefined.

Let me elaborate on it.

This other new pedal does half of what the compound already did (and better) plus some other new things (new for me at least), so to me it doesn't make sense to design and fab 2 different pedals that share 50% of the features. I also think this new unamed pedal is the stronger of the two, so I'm gonna focus on making *it* the feature-packed one.

I don't want to do away with the Compound's idea, though, and I'll redesign it into a smaller 2 or 3 knob version that's more focused and can do what the new one can't.

cloudscapes wrote:Well the cap near the LDR isn't really set up for a filter, since there's no series resistor between it and PWM output. Anyways, when I popped the cap out the choppiness didn't change much (a little). Can't remember exaclty why I had it there. The 220k and 100k are there to pull the PWM voltage range to what the LED needs.

sorry to dig this up again.

if you did not solve it i think this might, for reasons i will leave out this time unless it works ha. you are right about the filter thing i was looking at it backwardz but teh LED doesnt need a voltage really, it needs a current. I think the 100k in series with it is too high and probably why you did not see any dynamic range when you shunted the LDR with the 1meg and also why you do not have it soo choppy. The voltage across an LED is ~ constant as long as its conducting.

good luck.

[youtube]http://www.youtube.com/watch?v=JdqwXGB0944[/youtube]

Duuuuuuuuuuuuuude. And just when I was experiencing like 5 minutes without GAS. So so good.

yeah. that's fucking AWESOME.

please please please please please please please please please please please please please please please please please please
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PLEASE TAKE SOME PREORDERS.

or at least stack people. i would LOVE to get one of those.

PLEAAAAAAAAAAAAAASE.