Tonepad Tremulus Lune Build Notes and Review

[cnspedalbuilder]

I finished building the Tremulus Lune tremolo pedal from the Tonepad PCB this weekend. This should have been a very easy build, but the documentation is sparse, and there are a lot of contradictory numbers out there for pot values. I thought I would put my notes in one place to help others who might be in this situation and also provide a review. If anyone has any

Review
What I like: Very easy with few parts, Rate-indicating LED, "Smooth" control to vary between choppy and sine-wave tremolo, versatility (but see below), Compact PCB.
What I didn't like: Poor build doc, too many pots, Rate LED stays on in bypass, so you need to install a second LED on the switch. Also, PCB is single-sided, though this didn't create a problem. Although "Spacing" pot adds versatility, it makes it hard to dial in right speed. Most of all: Even at the "choppy" setting, the tremolo does not do a hard chop like the Vox Repeat Percussion. It sounds too tube-like for my tastes.
Verdict: If I had a do-over, I'd get the GuitarPCB.Com Apollo Tremolo, which has better docs and quality PCB construction. Or, I'd use a Vero Layout from Sabrotone or Tagboard Effects. Or I'd do the Moosapotamus Skippy or Parasit Green Currant instead.

Build Notes
-The tonepad layout instructions don't quite match the layout on my PCB. In particular, the Rate LED is not marked directly on the layout instructions, but it goes on the left side, by the set of 1k resistors. The Rate LED stays on in Bypass, which I find irritating. That means you will need to drill for an extra LED or do without a bypass LED. 
-The instructions show a 10k pot hooked up in series to a 1k pot to solder holes for a (single) speed pot. These correspond to coarse and fine timing pots. Everyone says that the fine timing is not needed so I didn't install (but see below).
-I used the "Photocoupler XVive VTL5C3 Work-alike" from Small Bear Electronics as the Vactrol. You can make one from an LED and an LDR, but this was an easy solution and the $6 investment was fine for me.
-There is a trimpot for gain. I like having this as a trim pot because I don't have much reason to adjust output volume once it is dialed in. Plus, I hate drilling holes for pots. 
-I ended up using 1k for Depth, 500k for Smooth, and 500k for Spacing, all Linear. I am not sure how I ended up with 500k smooth, but I think it had to do with looking at the instructions on the CommonSound PCB.
-The Speed Pot was a trial and error process. Because I removed "Fine" and I added a "symmetry mod" (see below) I experimented with a few different values, ranging from 100k Audio to where I eventually settled: 10k Linear. Most of the range on this pot is not useable. I'd estimate that from 0-50% the rates are way too slow, and from 85-100% it's too fast, so it is difficult to dial in the right speed. Ideally, I think you would probably use 50k Reverse Audio Taper, but I don't have one. Another option that I might try would be to wire 50k Audio Taper speed pot backwards.
-I did the symmetry mod as follows:

...except I used a switch instead of a pot. You can wire it with an SPDT, exactly like you would wire the pot. I did it with a DPDT so that the (1N4001) diodes would connect more elegantly:
               o--|<--o
Speed 2--o          o--Speed 3
               o-->|--o

This is probably a worthwhile mod. One setting gives you a "blip" like sound, other gives you more of a rotovibe sound.

-The settings are interactive. Changing spacing affects the "off" time on the trem, and that will affect the perceived speed. This means Spacing and Rate interact. The Symmetry Switch also changes perceived rate (rate becomes faster).

-If I were to do this again, I would omit the spacing pot. I don't have much use for variable spacing.

-If anyone knows whether there are mods to *increase* the choppiness on the pedal, I'd love to hear from you. I want this to replace my Repeat Percussion clone, which behaves badly depending on room temperature. Right now, this won't do the job.

[Elijah-Baley]

I hope the following video link could be useful, I don't want to mess up further.

https://www.youtube.com/watch?v=UW1r-d7y4Yw
https://www.youtube.com/watch?v=RRS-tsC4cp8
Our friend here is very good.

I built the Tremulus Lune using the third layout here http://tagboardeffects.blogspot.it/2013/03/tremulus-lune.html, but replacing the spacing trimmer with a pot 500k Linear. Five pots.
But to appreciate the Symmetry control the Speed pot is too much little and makes the effect very fast. I tested some pots and now I'm waiting for my definitive pot, a 100k anti log pot as Speed control. It will be very fast yet, but even slow enough with low setting to appreciate the Symmetry effect. I guess even with Spacing control.
To set the Speed you have to act on the its pot, of course, and on the electrolytic cap and the other non-polarized cap close to it. Bigger pot = low speed; Bigger caps = high speed.
The Tremulus Lune is one of my best effect.

I wouldn't say there's poor documentation, not if you looking for other sources.
http://fuzzcentral.ssguitar.com/tremulus.php
Another version: http://diy.musikding.de/wp-content/uploads/2013/06/tremoloschalt.pdf, I think this is my final version, not so different from the original layout from tagboard.

[vigilante397]

I personally love the Tremulus Lune, and I've built a couple on the Tonepad PCB, which I also love.

Question though: what made you choose the Tremulus Lune? Did you research it and listen to demos before deciding it was what you wanted?

If not, I could understand you not liking it and wanting something different. Personally the Tremulus gives the exact tremolo sound I was looking for, and it was a pretty simple and inexpensive build. I also find it to be very flexible, and mine can get pretty darn choppy when I'm looking for that helicopter effect.

[cnspedalbuilder]

Thanks for the replies. My review sounded too negative, but I didn't mean to sound that way. My goal was really to link up info about the circuit that I found on various threads.

I like the pedal, and I've gotten some good sounds out of the Trem Lune. All of my concerns were pretty minor--The build doc needs work (no mention of the indicator LED, schematic does not match layout, PCB layout does not exactly match layout in build doc) but these didn't present problems for me. The PCB was fine, I just like gpcb's boards better. The circuit itself is very nice--few parts, easy build! I can get a choppy sound out of it, but it doesn't quite capture what I can get w/my Hummingbird (modded RP circuit) clone. That's ok, it covers a pretty broad range of waveshapes, especially with spacing and symmetry. If I'm not playing with an amp that has tremolo, I'd probably keep this as a mainstay.

The only real problem is that damn speed pot. I'm using the value that's in the Tonepad doc (10k). I can only dial in useable speeds within a narrow range. I've tried 100k, 25k, and 10k linear and audio taper. I don't think a 500k pot would give better results, because the rate of variation across the range would be much higher. Elijah-Bailey, thanks for the tip about the capacitors. I should take a look at the component differences between the vero and tonepad versions.  Could you let me know your cap values? Also, if you use the 100kC taper pot, pls let us know how it works for you and whether you have to change cap values. 

[nocentelli]

I would recommend a 10uF timing cap, 100kC single speed pot and a 1k8 resistor instead of the 2k2 (sets the maximum speed). The reverse log speed pot makes dialling in the precise speed MUCH easier.

[Elijah-Baley]

The values of the components on my version are exactly those you can see on the veroboard by TagBoard GuitarFX's layout linked above. Same ICs, same caps and resistor. A VTL5C2 works fine. As I said, I replaced the Spacing trimmer with a pot (linear), and I changed just the Speed pot with a 100k, currently a linear, but I'm waiting for a reverse log. My order is late.

The reverse log speed pot makes dialling in the precise speed MUCH easier.

Right. I didn't try it yet, but that is what I expect, and, most important to me, it should be also more balanced with a reverse log. Indeed, with a 100k linear pot setted at 12 o'clock it is still very slow.
I can see how a reverse log works in the video linked by me in the second post.

[nocentelli]

To set the Speed you have to act on the its pot, of course, and on the electrolytic cap and the other non-polarized cap close to it. Bigger pot = low speed; Bigger caps = high speed.

To be clear, a bigger cap gives a slower minimum speed.

[PRR]

> I can only dial in useable speeds within a narrow range. I've tried 100k, 25k, and 10k linear and audio taper.

Use audio taper, but swap the ends, and turn the knob "backward".

If that gives good sweep, but "backward" bothers you, get Reverse Audio.

[merlinb]

Rate LED stays on in bypass, so you need to install a second LED on the switch.

According to this wiring diagram and schem the rate LED is switched off during bypass?
http://commonsound.org/tremulus/pcb2.4.1/schematic.pdf
http://commonsound.org/tremulus/pcb2.4.2/wiring_pcb_2.4.2.pdf

[cnspedalbuilder]

Great advice I'll experiment with the cap values and audio taper with backward wiring!

Merlin, that info is for the 4ms kit/PCB not the Tonepad. BTW, I tried wiring the LED ground to the switch. That worked for indicator status, but it no longer flashed at rate setting and the depth of the trem effect was almost completely gone. Schematic was of little use in figuring that part out. It's possible that I had a poor solder joint on the switch, but I think that the LED ground might actually need to be in the solder pad for the pedal to work properly.

Of course, it' s no big deal to wire a second LED, just means I have to pop another hole in the enclosure.