Tremulus Lune Baby-- Help on LFO speed

[BadIdeas]

I am so excited because I just built my first effect!!!
There is a problem though...
I built the Tremulus Lune using the RTS board from Tonepad, but with one major difference: I housed it in a Crybaby shell. The original calls for a 10k speed pot, but of course I used the 100k stock pot. It is actually connected to a toggle for the stock pot and a 100k linear pot for manual control. I also replaced the Spacing pot with a 270k resistor; I'm not really sure what that was for anyway.
As you may predict, the effect is W...A...Y...  T...OO... S...L...OW...
Looking ahead, I also subbed the 100uF cap in the LFO for a 10uF, but apparently that was not the timing cap, or not the only timing cap. I haven't learned about LFO's yet.

How can I get usable speeds while using a 100k pot? Is there any reason why I should change the 10uF back to 100uF?

Frank admission: I also neglected the current-limiting resistor for my LED and fried it. The only blue one I had...

[Scruffie]

Put a 10k Resistor across lugs 1&3 of the pot and you'll approximate a 10k value (actually 9ish but close enough)

[BadIdeas]

Put a 10k Resistor across lugs 1&3 of the pot and you'll approximate a 10k value (actually 9ish but close enough)

That's an idea. I just did some searching (like I should have done to begin with) and haven't found an answer yet, but I did notice that I put in a .1uF cap where it should have been .01uF. Does this also affect the timing? I will probably change it anyway, but I am curious.
Actually, here is the thread that led to the discovery:
http://www.diystompboxes.com/smfforum/index.php?topic=88346.0

The current commonsound schematic for the Lune lists 100k and 10k pots for the speed (http://commonsound.org/tremulus/pcb2.4.1/schematic.pdf) while tonepad lists 10k and 1k (http://tonepad.com/getFile.asp?id=84).

> commonsound schematic for the Lune lists 100k and 10k pots for the speed ... while tonepad lists 10k and 1k

AND the 10u and 0.001u caps change to 100u and 0.01u.

They work the same.

If I can simply substitute a cap or something, that would be preferable to trying to put a resistor across the wires, I think. My wiring skills are still not so good, and the pedal is crammed with them. I'll think about my options before I decide.

[Le québécois]

I don't know about the possible interaction of the mods you have done (like the spacing pot sub for 270K) but I have this thing on a breadboard and what really have an impact on speed is the 100uF cap. You can easily go to 1uf (the smaller, the faster). I even try 0.33 Uf and althoug very fast, it can be use.

[BadIdeas]

Ok, I just plugged the pedal in again (haven't changed anything yet) and I noticed that
a) The manual speed pot is wired backwards
b) When it is turned almost all the way up, it stops until I turn it down a ways again. It barely starts to get fluttery when it stops, not fast enough for fastest usable speeds
c) The expression pot is wired right (faster w/ toe down) but isn't near fast enough to be worth "expressing" with. I will probably turn it a little and then put the rack back on.
I think I will try 3.3 or 2.2 uF and I may have to rewire the toggle switch (sigh) and put a 100R or so in series with the manual pot.
Thanks for your suggestions, I will report later.

[BadIdeas]

Almost there... but it's time to quit for the day.
After thinking more about it, I went with a 10k pot in series with the manual Speed pot (why did I think 100R?). Somehow, I also managed to somehow reverse the wah pot, but it's back in order now. I tried replaced the .1uF with a .001uF in the feedback loop in the LFO, and I'm still now sure what it is for.
I tried a 2.2uF timing cap and it was a little too fast, 3.3uF worked better.
The main issue now is the weird taper on the wah pot. It transitions from slow to fast too suddenly, with no real room for expression. I think the solution is to put a resistor between the wiper and one of the lugs. I'm not sure what value to use, but probably more that 100k.
Sunday afternoon is probably the earliest I can return to this, but I will report again once I do. In the meantime, it will continue to be in the back of my mind what resistor to use and if I will need to change the timing cap again.

[BadIdeas]

I finally found the time to revisit this again, and I decided that trying to get the wah pot AND the linear pot to both work was a little too complicated, so I used the home for Manual Speed for Spacing instead. It is VERY close to working the way I want. The actual measured value of the pot was about 126k plus a little more. I adjusted the rack/pinion so that maximum resistance (toe up, heel down) is about 120k, and I think the resistance at maximum speed is about 6k, maybe a little less. This seems to be almost the perfect spot, but the taper still makes it transition through the faster speeds too quickly. I think a tapering resistor could help to couteract this if I choose the right value and go with a smaller timing cap. I read the secret life of pots (required reading, really) and I'm a little confused by this paragraph, particularly what he is saying about "b":

We're assuming the total pot resistance R is split into an R1 at the CW side and R2 on the CCW side, with R3 paralleled with R2. We'll let "a" represent the fraction of the total resistance R that the wiper has turned, and "b" be the fraction of R that R3 is. When we get out the algebra books and do the math, we find out that we can show that the ratio of output voltage to input voltage is that odd looking fraction in the picture. When we calculate out the results, we find that the divider ratio of Vout to Vin is shaped something like a true logarithmic tapered pot if we pick the right value for b. If b happens to be 1/4 to 1/5, the resulting voltage division is remarkably close to a true logarithmic pot, probably closer than a two segment approximation that we could buy! Wow! No more waiting for volume control pots!

Here's what we see when we do the math:

Using a graphing calculator to help me find similar max/min speeds (assuming I did my part of the math right) I got seemingly good results using a 2.2uF timing cap and a 2.2k-3.3k resistor. This paragraph leads me to believe I need to use a larger resistor, though, or the coutner-taper may be way to extreme. Am I understanding this right?

[flintstoned]

Another bad idea, you could wire up a toggle switch to have a slow sweep and a fast sweep so you can have more control through the range on the treadle.

[BadIdeas]

I'm satisfied with the range of motion, I just need it to be spread a bit more naturally when I'm expressing. Currently, I get from about .4Hz to 8Hz. I'm looking for similar range with a more even sweep.