Category: Modulation

Tinkering with vibrato

So, while waiting for money for amp parts to materialize, and amp parts to arrive in the mail, for some indiscernible reason I wanted to find out more about what makes a vibrato circuit tick (ha-ha).

I started looking at and playing with the Wobbletron by Tim Escobedo and some of the vibrato circuits in the “Stompboxology” papers. The Wobbletron is fun, but supposedly also quite hard to make, so I wanted to put something similar together for myself while learning something new in the process.


Trying to convert the phase shift circuit to opamp I noticed how similar this was to the first stage of both the Phase 90 and the Micro Fazer. I ended up ripping off the first stage of the Phase 90.

As for the LFO I went through 7-8 different ones from various circuits (Tremulus Lune, Trembulator, Zombie Chorus, Ultra Flanger, Phase 90, Micro Fazer, Wobbletron etc.), but ended up with something very similar to the Zombie Chorus and Ultra Flanger that I liked the most.

I also tried different optocouplers in place of the FET, but they didn’t come close, so it’s the 2N5952 from the Phase 90 (which I had a bunch of). There’s a bonus in that since there’s only one stage you don’t have to match several of them. Other’s might work equally well, but I haven’t tried.

Finally, the depth pot. No idea where that came from. Seems to work well, but value subject to some experimentation.


I did breadboard this circuit and had zero noise issues, but haven’t tried the vero layout yet. I’m fairly confident it’ll be good, but you never know 😉

Let me know what you think! Next, tap-tempo LFO would be cool…

Update (08.11.2013): Now verified as working, thanks to Michael. Also, now that I’ve got the tap-tempo micro controller working I’ve modified this circuit to go with it. Stay tuned 🙂

Updated: 8 November, 2013 — 23:21


This one is a bit unusual in as much as I’ve already built it and verified it as working. Here’s a vero layout for Tim Escobedo’s Wobbletron, I believe it’s a vibrato-thingy similar to what can be found in some old amps.


The original schematic (search for “tim escobedo wobbletron schematic”, I’m sure you’ll find it) called for a J201, which I have plenty of. Problem was not a single one worked.

So I tried a few 2N5457s and found two that gave a slight wobble. What really worked (almost too well) was a J112 (all of the ones I had gave lots of wobble). Experimenting for a while I came to the conclusion I wanted to stick with the J112, but greatly lower the 220K resistor between “Depth 1” and ground. Since the 2N5457 required a larger resistance here I figured I’d make it a trimpot.

Insert J112 (or 2N5457, or some other JFET maybe), set frequency fully clockwise (faster) and depth fully counter clockwise. Now adjust trimpot to where you want your depth minimum setting to be (probably at no, or very slight wobble). Now you can try playing with the range of the depth pot; I had good results with a B250k, but maybe something smaller/larger will work better with your JFET.

Anyway, good luck 🙂

Updated: 22 April, 2013 — 01:11

Request: Catalinbread Pareidolia

There have been a few requests for this one. Let me know if you build it and it works. This should fit in a 1590B enclosure.

Update (11.10.2012): Revision 1; changed Q3 and Q6 to 2N5457s.

Update (22.01.2012): Revision 2; I had mistakenly labeled this as requiring 44 cuts while it only needs 43. Thanks to Nocentelli for spotting this.

Update (01.02.2012): Built this one tonight. Had to reorient the depth and rate pots (layout has been updated), but otherwise it worked like a charm.

Update (18.12.2012): Voltage readings from my build as requested:

Power supply: 8.88V

All pots fully CW.

1 +3.75V 0V +8.88V
2 +3.75V +3.75V 0V
3 +3.75V +3.70V +7.46V
4 0V +7.46V
5 +3.72V +3.72V
6 +3.72V +3.72V
7 +3.70V +2.80V
8 +8.88V +3.64V
9 +1.53V
10 +2.82V
11 ~+15mV
12 0V
13 +1.73V
14 +1.73V
15 +0.93V
16 +0.93
Q1 Q2 Q3 Q4 Q5 Q6
D +8.88V +5.71V +1.21V +8.88V +6.02V +1.21V
S +5.71V +0.90V +1.21V +6.02V +0.96V +1.21V
G +4.13V +2.7mV ~+4.3mV +4.21V +2.6mV ~+3.8mV

Update (30.04.2013): Just adding the schematic that I drew based on the trace made by KindaFuzzy over at FSB.


Updated: 30 April, 2013 — 22:46

Request: Tremulus Lune

I don’t know much about this effect other than it’s a tremolo of some sort, and I’m sure it sounds nice. Let me know if you verify the layout.

Update (13.12.2011): Thanks to Mark for verifying the layout as working.

Update (10.02.2012): I finished my build tonight. The internals look a bit messy ’cause I didn’t really feel like being too neat this time; just wanted to get this thing up and running. It’s great fun and a cool project.

Update (15.02.2013): As requested her are working voltages from my own build for debugging purposes:

Battery at 8.97v, all pots fully CW, and speed indicator LED on and flashing quite fast.

U0 U1 U2
1 +7.53V +3.76V ~+4.5-5V
2 0V +3.76V ~+4.8V
3 +8.97V +3.74V ~+4.9V
4 0V 0V
5 +3.74V ~+4.8V
6 +3.76V ~+4.8V
7 +3.69V ~+4.8V
8 +7.54V +7.54V
Updated: 12 April, 2013 — 14:59

Echo Base digital delay

I was looking for another delay based on the PT2399 and stumbled over the Echo Base. It seems like a neat delay with lots of options, but I have yet to hear what it sounds like. I’ll take my chances.

Anyway, here’s a still to be verified vero layout I just did. I plan on trying this one out pretty soon, but I thought I’d share it as I’m pretty sure the layout is correct (in so far as the schematic I based it on is correct, of course).

Update (04.09.2011): Built this one tonight and with a few minor fixes this is now verified. The “Time” and “Mod speed” pots were re-oriented and the feedback switch was fixed.

Update (06.08.2012): I’ve had this one in a box for quite a while, but haven’t gotten around to take those pictures. Here’s what my build looks like, and it is a bit untidy (also knobs still needed). Kid got to choose graphics 🙂

Updated: 21 December, 2012 — 21:08

ADA Flanger

I always wanted to make this flanger! This vero layout is based on a schematic by moosapotamus. Given the size of this thing I’d be surprised if it doesn’t contain a few mistakes.

Update (14.07.2011): I’ve worked on populating this board over the last couple days and I found two mistakes on the vero layout (so far), two resistors both labeled R63 and C21 should be 1uF and not 1nF. I’ll update the layout, but I would like to verify that the layout is correct first. So far I’ve got sound but no flanging and next step is giving the whole board a look over to make sure I’ve got all the components in the right places. Wish me luck…

Update (29.07.2011): Just finished populating, debugging and correcting my first take on the MN3007 ADA Flanger vero circuit, and now it works!

There were two mistakes on the initial vero layout, a mislabeling of R62 and C21 should have been 1uF and not 1nF. The vero layout has been updated and is now verified.

Note: You’ll notice Q1 looks a little strange. I used a 2N3819 with a different pinout so I had to bend the legs around a bit. Also, don’t count on the trimmer settings you see in this picture, I was playing around with the adjustments.

Update (20.10.2011): Fixed dead picture link.

Update (14.11.2012): Finally got around to calibrating and boxing this one up. What a great flanger (and what a complicated build)!

You can kind of make out my trimmer settings here too, which may or may not be of any help.

Update (16.11.2012): It’s worth mentioning that I used the latching relay vero and a soft-touch stomp switch in place of a 3PDT (seen in the lower left part of the gut shot). Also, in the upper left corner, you’ll notice a small voltage doubler circuit that converts +9v to +18v. I didn’t have any luck getting enough voltage to the circuit in the end, trying both ICL7660S, MAX1044 and LT1054. The voltage doubler circuit itself was able to put out about +17v, but this was for some reason that I should probably know loaded down to about +15v when connecting it to the main circuit. In short the circuit is getting a bit less voltage than it should, but I was able to get it working fine regardless.

Updated: 21 December, 2012 — 21:05

Mid-Fi Clari(not)

Here’s a vero layout of the Mid-Fi Clari(not). It sounds like a really fun little circuit.

Update (13.10.2011): Mod suggestion from Milkit: “Cut the trace joining pins 1 & 8 of the LM386, join them back together with an spst switch & you have yourself a fuzz cut switch. It doesn’t cut out the fuzz totally, but it’s not so prominent, kinda becomes more of an overdriven sound.”

Update (06.08.2012): Finished this effect the other night and it’s really fun, but maybe not so useful. Those knobs needs to come off again, but other than that I’m fairly happy with it.

Updated: 21 December, 2012 — 21:02

Request: Double delay- and modulation add-ons for the Aqua Puss

Here’s a vero layout for the double delay add-on to the Aqua Puss.

Update (20.02.2011): Fixed a connection between pin 7 on the two ICs.

Update (20.02.2011): Here’s a vero layout for abfackeln’s modulation add-on as well.

Update (22.02.2011): The double delay vero layout is verified by Mat as working.

Update (22.11.2011): I guess this just passed me by. The modulation layout is also verified as working.

Updated: 21 December, 2012 — 21:02

MXR Phase 90

Did a vero layout for the MXR Phase 90 effect yesterday. Looked over it once after I was done, but can’t yet guarantee that it works. Will have to make it one day soon.

MXR Phase 90 vero layout

Update (12.09.2010): Went over the layout a second time and corrected a small error; I had the output on the wrong side of the output cap, and consequently had to add another column to make room for the correct output. I’m now confident enough about the layout that I’ll start working on a vero board and source the necessary parts.

Update (14.07.2011): Finished this one the other day and as with the Omnidrive I’m not really that happy about the outcome visually, but unlike the Omnidrive I think this one sounds great!

This was a tight fit in a 1590B enclosure and putting it together was great fun. It was only after having soldered the last wire I realized I forgot to take a picture of the board itself, and I didn’t want to take it apart again, so no board shot of this one, sorry.

Update (20.10.2011): Fixed dead picture links.

Updated: 21 December, 2012 — 20:44
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