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I’ve built several pedals now and this is my first tremolo circuit build. Based around a “Tremulus Lune” circuit, this takes mods well. (All I added was a “Symmetry” pot that swings between two opposing 1N4148 diodes to ramp ‘up’, ‘down’ or any where in between in the LFO portion of the circuit.) Now, on to the photos . . . .
The completed, tested pedal . . .
Gutshot . . .
Build process . . . . (I like to use a piece of cardboard on which to place the hardware for getting the best wire lengths and a good approximation of their respective placements.)
I really like Barry’s Best Wire for building. When the pots are all off-boar, the wiring holds the PCB in place.
The “Symmetry” mod is as shown in this edited schematic (mods are underlined in red) . . . .
Thanks for reading. Happy building!
Re: Build process . . . . (I like to use a piece of cardboard on which to place the hardware for getting the best wire lengths and a good approximation of their respective placements.)
That is a very good idea. I had not thought about that before and was wondering how to get the exact wire lengths for a tidy build. It seems like I get wire lengths that are too long or too short. I will have to try that.
Did you use waterslide paper or photopaper for your graphics?
Big O – I use waterslide primarily. And for this one. I found a YouTube video that works for me when I use waterslide decals.
Printing and Applying Waterslide Decals
On larger than BB enclosures, I prefer to go with Barry’s method and use photopaper. I find decals too large who bigger than BB. Here’s a shot of a build I did with Barry’s “Super Drive 70’s” that uses photopaper . . . .
my bud – Thanks! If \ when I build another, I’m going to try the Symmetry mod in series, after the 2K7 Ω resistor (R8), instead of in parallel. In series, may even go with a toggle instead of a pot.
Excellent all the way around Ccow. I love the thorough posts with great care in taking photos as well.
Impressive!! I recently built Aion’s version of the Tremulus Lune, which they call the Luna. That, too, includes a symmetry control, but as a standard part of the circuit. Doesn’t have the speed range or trem/buffer switches, though. In any case, it’s a nice alternative to the ubiquitous EA tremolos that everybody seems to offer.
Bob – Thank you! Whenever I dig into one of Barry’s builds, I like to look up more information on the referenced circuit and see what others are doing with it. More often than not, I will try to incorporate any useful (playful) mods to my builds. I also have an EA Trem in my build queue, but I think I’m gonna like this one better.
Deep Southerly (African) greetings to you all.
WRT the Apollo I’m curious as to whether the symmetry mod combined with the speed switch can achieve a slow ramp as Cybercow suggested, in which case it’s almost obligatory for my purposes (mostly nefarious, I have to admit). This would cause it to behave more like a VCA if I understand the mod correctly.
My observation is that the EA doesn’t provide the choppiness of the Apollo. It’s more like a straightforward sine wave to my hearing; I don’t have a ‘scope to verify this. But it’s a ‘musical’ circuit nonetheless, undoubtedly less versatile than the Apollo but still very usable. My only reservation is that it’s not slow enough for my taste and I was wondering whether a similar mod to the Apollo speed switch might be doable.
I assume (on the basis of no evidence at all) that the timing cap is C5, in which case one of Barry’s DPDT switch mods to add a cap in parallel to the 470uF there might do the trick.
Thanks as always for the interesting thread. Your thoughts and comments in due course will be greatly appreciated.
HI Cybercow: Tried the series mod on a temporary basis, but found it limited the range of the rate pot quite drastically. Could of course be that I miswired it, took the connection from the bottom of R8 to the symmetry pot and then onto the rate pot. However, the mod you listed works nicely. Thanks goodness for croc clips.
I’m interested in the diode SPDT mod, but no rush. When/if you have time …
Best and thanks again.
mybud – thanks for trying that out. Good to know. I won’t even bother after hearing your results. As for the SPDT toggle mod, I’ll skip that too considering it was associated with moving the position of the “Symmetry” mod.
A simpler “Symmetry” mod involving a toggle would be to apply a DPDT 3-way toggle and the two diodes. In the middle position, bypass both diodes, and in the other two positions, just inject one diode in one direction and the other diode facing the other way. So the result would be either an up-sweep only, a down-sweep only or bypass the diodes altogether for a symmetrical LFO.
Looking at the gunshots of Cybercow”s Shiver Quiver, I like the idea of using the 3PDT Wiring Board and 2 LEDs, one for rate and one for on/off. I see there is a resistor added between S4 and S5. Can someone please tell me what I need to be aware of with this mod? Is this just using two different resistors for the two LEDs? I don’t see any resistor that was left off the main board as is usually the case when using a 3PDT Wiring Board. (I tried this question on another thread and didn’t receive any replies so I thought I’d try again on this thread)
Slider – the added resistor between S4 & S5 is merely a CLR for the Rate indicator LED. I prefer it a bit less bright and the added CLR reduces the brightens of it.
I used separate CLRs for the Rate and On-Off LEDs. The on-board CLR on the 3PDT Wiring board is for the On-Off indicator and the added resistor between S4 & S5 is for the Rate LED.
I didn’t use a bi-color LED on the 3PDT Wiring Board – I just wanted an On-Off indicator. I did not work up a scheme for using 2 LEDs on the 3PDT Wiring board (one for On-Off and the other Rte indication. That would require a different bit of attention for such re-wiring.
so i find myself reviewing this cat’s, er uh, cow’s thoughtful project notes because i want to build it to. i noticed this little gem on R7, seems a handy trick to know. sharing for other shade tree folks. thank you, mr. cow!
SofNWhat – good eye-catch. Thanks for the shout out. I initially added that little ‘loop’ in R7’s leg because I thought I might be adding the symmetry diodes modification to the component side of the PCB. But it turned out that the symmetry diodes worked out better when they’re attached directly to the ‘Symmetry” pot. The ‘leg loop’ trick is one I learned decades ago repairing organs, synths and amps.
so cool. would you use the same technique from the bottom of the pcb, leaving a bit of a loop from the component lead there too?
a good friend here in Chicago just got his Oberheim and an old Hammond back from the shop. great old stuff. i love going to listen, even though it’s been a year’s worth of basement rehearsals since the ‘Rona.
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