# How would you slow down the Woodpecker tremolo rate?



## xefned (Aug 29, 2021)

I know this seems like a crazy question since there's a mode switch, and 2 of the positions go plenty slow, but those other positions also seem to change the ramp, or waveform shape. I only like it when SW1 is in the center (NC) position.

But that position doesn't go quite slow enough to match the tempo of a lot of songs. It's close though.

I'm guessing I should start with either R10 or C6. Any suggestions appreciated.

Woodpecker fragment attached.


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## Mcknib (Aug 30, 2021)

Increase the value of those 2 caps

Afaik the charge and discharge time of the capacitors sets the rate, so bigger values would take longer to charge and discharge and decrease speed

There's a calculator here



			https://www.allaboutcircuits.com/tools/capacitor-Charge-and-time-constant-calculator/


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## xefned (Aug 30, 2021)

OK, thanks for that calculator Mcknib.

Since I'm ditching SW1 entirely, I'll try increasing the value of C6 to 1.5µF.

Thanks for your help!


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## xefned (Sep 1, 2021)

Verdict: changing C6 to 2.2µF gave me what I wanted—a wider range of speeds without using the mode switch. I can slow it down for mid-tempo songs in the middle switch setting.

I was wrong about the ramp changing with the mode switch. That was just a psychoacoustic hallucination from rapidly switching from fast to slow mode. Once you start playing along to the newly set tempo, the brain realigns its expectations. (I recorded the stock values with my phone to go back and compare.) The top speed is still hummingbird fast with this cap change. (Just a hair slower, but still unusably fast when fully clockwise.)

Higher resistance for the rate pot = slower repeats.

I also tried a 250k pot for the rate pot (after changing C6 to 2µ2) and it's way slow, to the point that it stops oscillating toward the bottom 3rd of the pot travel. A 250k pot might work great with the stock C6 value. But I don't know; I didn't try it. I also tried some other stupid shit I won't bore you with.

I find this a vast improvement, but I don't necessarily recommend it unless this sounds appealing to you.
Final values:
C6: 2.2µF
C8: 1µF (barely slower than middle position. Might be useful if you're having a hard time dialing in an exact tempo.)
C7: 6.8µF (plenty slow for rock and roll. slightly more usable than 10µF.)


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## fig (Sep 1, 2021)

xefned said:


> That was just a psychoacoustic hallucination from rapidly switching from fast to slow mode



There are simply too many directions I could take that...


Thanks for the writeup! I fiddled with an EA's tempo. I ended up with a 2u2 as well. I was going to check into that "stalling" you mentioned but forgot. Now I have a note to do so.


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## xefned (Sep 1, 2021)

Keep us posted!

This is the tremolo I've always wanted, and now I'm already deciding to re-house it in a larger enclosure so I can add a jack for plugging in an expression pedal.

Also, I'm already thinking about building one for the bass player so we can coordinate for a crazy simultaneous stutter breakdown.


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## xefned (Oct 17, 2021)

I love this pedal so much that I built a second one! Now I have a white one and a green one just for backup I guess.

After much experimentation, here are my recommendations, for whatever they're worth:


For the speed timing caps, *use 2.2µF for C6, 4.7µF for C7, and 1µF for C8* for the greatest flexibility.
*Go with the stock value for the depth pot*. (In another thread, jjjimi84 had good luck using 25k saying “…that seemed to make everything come alive.”) I tried 20k in this build and, for me, it rendered the first 1/3 - 1/2 of travel pointless. That's fine though because I like the depth either *ALL* the way on or *MOST* of the way on, which is easily achieved with half a pot rotation. YMMV of course. There may be an unknown factor that made that work for jjjimi84.
*Expression jack probably isn't worth doing*. It's fun to dick around with, but not necessary.
Most fun pedal I've ever built.


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## xefned (Oct 23, 2021)

Woke up with an epiphany about the expression jack, I wired that last one from the SLEEVE to the TIP, but I found the greatest range of resistance when wiring from RING to TIP. Rewired, and I'm back to liking the expression jack quite a lot. This reinforces my hypothesis that a 50k expression pedal won't cut it. It has to be the 100k Moog pedal.

Epiphany #2? (Duh) I could simply reverse the expression jack lugs so I could use "Standard" mode with the Moog EP-3 expression pedal; no need to use the alternate switch on bottom of Moog pedal as previously mentioned.  I rewired both of my pedals for standard mode. 

Finally: quite by accident, I discovered that shorting the newly-freed expression jack sleeve to ground gave the ability to turn off the effect at the lowest expression setting. Then you increase it over an imaginary hump as it swells back to "ON" position. I don't know why that works, but it does. And it's nothing I've seen in any demos of the Hummingbird. I'll have to make a video, cuz no one will no what I'm talking about otherwise.


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## fig (Oct 23, 2021)

xefned said:


> Finally: quite by accident, I discovered that shorting the newly-freed expression jack sleeve to ground gave the ability to turn off the effect at the lowest expression setting. Then you increase it over an imaginary hump as it swells back to "ON" position. I don't know why that works, but it does. And it's nothing I've seen in any demos of the Hummingbird. I'll have to make a video, cuz no one will no what I'm talking about otherwise.


I think I follow you. The LFO normally has to "catch up" or "recover" when first engaged? The re-wiring may provide a less resistive path to ground needed to stabilize the LFO....I dunno, I've never taken any electrical or electronics classes so it's purely speculative.


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## xefned (Oct 23, 2021)

fig said:


> I think I follow you. The LFO normally has to "catch up" or "recover" when first engaged? The re-wiring may provide a less resistive path to ground needed to stabilize the LFO....I dunno, I've never taken any electrical or electronics classes so it's purely speculative.



I'll be honest, I don't have a clue. But it's not when I engage the pedal. The pedal is on all the time in this scenario.

Then I push my heel down on the expression pedal, and it's just like I've turned the thing off. And as I slowly step on the gas, the volume seems to faintly swell as the effect is engaged. But the effect is actually ON the whole time. It's weird.

I only discovered it because I needed another switched *stereo* jack and this was the only kind I had. The only apparent difference is that the sleeve is automatically grounded to the case.

I think you're right though, I'm basically crashing the LFO and creating a non-working pedal at the highest pot resistance. So, nothing to get too excited about.   Still, it's kind of a cool accident to discover.






EDIT: 1 year later, I added plastic washers to the expression jack to keep it from grounding to the case. (This fixes the LFO crash.)
It was a cool little accident to play with, but I wanted it to be *right.* Future travelers: use the plastic insulated-style jack that doesn't ground the sleeve to the enclosure.


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