Magnavibe vibrato/tremolo blend mod for rotary speaker effect

[duck_arse]

have someone throw it to you.

[Kipper4]

Hey I got 18nf caps?
weird or what.........

[duck_arse]

bee zar. yello?

[Kipper4]

Yessum Yello.....

[Ben Lyman]

Been a long time in the making. it's my first 4knob pedal and board mounted pots to boot. At least I have a working layout now in case I ever want to make another pedal with 4 knobs. It's not exactly what I set out to make or what I expected but I'm very happy with the results. It is a sonic mangler with its own personality. My so called "tremolo" knob is something else, I think Jon may have tried to explain what was going on but I'm not sure. Either way, it's pretty cool and makes some very useable sounds. Big thanks to kipper for sparking the idea for the trem mod and another big thanks to duck for the great POS mods 

[Kipper4]

Great stuff Ben.
Thanks to this quest you now have the honour of having a cap named after you too.

[duck_arse]

sounds pretty good there, "three vibes" Ben. are ya gunna show yr layout?

[Ben Lyman]

I haven't yet measured the box out to save my 4 knob drilling layout.
Did you mean the component  board layout that I made in DIYLC?
It's probably not nearly as good as something you could come up with, it's like a long rectangle with all the pots mounted in a row.

[duck_arse]

here is the finished something, not exactly a magnavibe (and a project not exactly finished).

circuit here, in colour:
http://i.imgur.com/wjw7Ats.png
and B/W here:
http://i.imgur.com/KR9aFCa.png
this version replaces the now deleted circuit from post #117.

here is the perfboard layout, on black back (it is quite large):
http://i.imgur.com/9S3a8W1.png

for those wanting a light background, ask, and I'll send the diylc.diy file, and you can mess the colours to your hearts content.

the boss told me no corner holes, 24x17 holes, and the name, so take it up with him. I think the circuit dia matches the board, if you spot an error, let me know, it has not been verified yet. it is intended for "5 minute vactrols" style vactrols. there is an alternate placement for the feedback cap if a squeel stop R is needed, also shown.

ask kipper nicely, I think he has posted a sound clip matching this version (you REALLY don't want to hear mine). we next doing vibe with envelope-controlled rate. stay tuned.

[Ben Lyman]

That's great, I got some catching up to do. What if all I want is a simple phaser without all the extra stuff? You know like a Phase 90 or Small Stone... but easier and less parts?!?

[Kipper4]

I think this was the one in question

https://www.youtube.com/watch?v=cPEF2HK4TB8

You got a lot of catching up to do Mr L.

Simple phaser you say. Less parts, thats not easy.
I'd be inclined to go for more parts ,more phase stages, probably around 8 stages to get a good depth of phaser.
Since theres not so much trouble getting the 2n5952 in the US id try the phase 100.

If you want to I could further develop, with your input, an op amp phaser i've had on the back burner. As soon as I'm done with Ducks devonian and the Enveloped tremolo I got going on.

[duck_arse]

what "extra stuff"?

easier than a P90 would be a P45. you could even hack in your special psssso oscillator.

I'd be inclined to go for more parts ,more phase stages, probably around 8 stages ....

now yer talkin'.

[Ben Lyman]

I think I have all the parts for a P90 except the D1 zener. is that important?

[duck_arse]

you can use 4V7 or 5V1 or 5V6 or 6V2, if that's what you have. otherwise, use two red leds in series, K to ground. the voltage you need depends on the fets you have.

[Ben Lyman]

Thanks Duck, I don't have any zeners at all. I am having a hard time understanding the data sheets, trying to learn what a zener is/does differently than others.
I have 1n5817, 1n400X, 1n34A, 1n270, 1n4148 and 1n914.
Should I stockpile some zeners as well?
What's a good common type, if so?

[duck_arse]

err - three red leds (1V7 * 3) or two other colour with higher Vf.

if you are buying in stock, you want 400mW in 4V7 and 5V6, which will cover nearly all 9V, biased-fet circuits. you might only be able to get 1W these days, but they're fine.

[Ben Lyman]

Thanks Duck, I'm guessing I should get a few 1n4732 and 1n4734.
I see they also have 1n4733 5v1 zener, maybe a few of those too

[Mark Hammer]

Just finished firing mine up.  I must have gotten lucky with my parts.  Grabbed a superbright red LED and one of the LDRs in the drawer, and it worked like a charm.  Nothing needed changing or tailoring.  Works great.

Instead of a vibrato-to-tremolo pot, I simply stuck in a 9k1 resistor and a toggle to short/unshort it. Nothing special about 9k1 other than I had plenty and didn't want to run out of 10k.

This is a nice little circuit.  The vibrato is certainly not the sort of seasick effect you might get out of a phaser or chorus with the dry signal lifted, but it's a nice coloration; the kind of thing you don't mind leaving on for a while if you're playing rhythm.

The option to transform it into tremolo is a real plus in my books.  Note that the entire LFO and depth range will be useful for tremolo, while only a portion of each of those ranges will really be useful for vibrato.  I would imagine that, were one to use two cascaded stages to produce a wider pitch shift, you'd still be able to hear the effect at slightly slower speeds and lesser depth.  But with one stage, the LFO needs to be relatively fast and furious for the effect to be clearly heard.

All in all, though, big return for a few parts, a small hunk of perf, and a few hours of tinkering.  Mine is going into a little 12V "lunchbox" battery-powered amp.

[Kipper4]

Excellant. A mini magnatone amp.
RESULT........

[Ben Lyman]

Mark, can you share the schematic that you used? There's been so many experimental posts lately

Excellant. A mini magnatone amp.
RESULT........

"The Midgetone"