French Cookbook Vibrato.

bobbletrox · January 14, 2005, 05:02:05 AM

http://partouze.chez.tiscali.fr/stomp/2tranvibrato.jpg

I'd like to try this circuit out, but a few points have me weirded out...

1) R7 is in the signal path even when the effect is bypassed, won't this affect the tone?
2) Would the two transistors (AC125's) have to be matched, or can they just be any old hfe?
3) The signal doesn't go through the circuit...and it's creeping me out! Shouldn't there be caps on the in/output at least?

:?

bobbletrox · January 14, 2005, 05:12:23 AM

Wait...is this thing even a true pitch modulating vibrato? :shock:

Paul Perry (Frostwave) · January 14, 2005, 06:38:52 AM

Quote from: bobbletroxWait...is this thing even a true pitch modulating vibrato? :shock:

It certainly isn't.
It's a phase shift oscillator (on the left) driving a transistor acting as a variable resistor, forming a voltage divider, so the signal is decreased more or less as the LFO swings.
It's cheap, I think it will work, but I would call it a tremelo, because.. that is what it is.

puretube · January 14, 2005, 10:14:29 AM

it got volume drop - even switched to bypass -...

Paul Marossy · January 14, 2005, 10:50:06 AM

I had a problem with volume drop with "Laurier's Vibrato" which does seem to have some vibrato characteristics, but nothing I did to increase the output worked... :x

David · January 14, 2005, 11:47:46 AM

Quote from: Paul MarossyI had a problem with volume drop with "Laurier's Vibrato" which does seem to have some vibrato characteristics, but nothing I did to increase the output worked... :x

... You mean until you built the EA Tremolo?

Do any of Laurier's circuits work? I've tried three and failed on all of them!

Paul Marossy · January 14, 2005, 11:49:51 AM

Actually, I think I built the EA Tremolo before I built his vibrato circuit. When I think about it, I've built two of his circuits, and neither worked, at least not like anticipated. :x

StephenGiles · January 14, 2005, 01:13:00 PM

It looks like a reverse engineering of a Coloursound Tremolo.
Stephen

Paul Perry (Frostwave) · January 14, 2005, 05:53:25 PM

From the way it is designed, it HAS to have a volume drop, because when bypassed the signal is straight thru, and when operatign the signal is being voltage divided by a variable amount (so it must average less than unity).

bobbletrox · January 14, 2005, 06:11:38 PM

Quote from: Paul Perry (Frostwave)
It certainly isn't.
It's a phase shift oscillator (on the left) driving a transistor acting as a variable resistor, forming a voltage divider, so the signal is decreased more or less as the LFO swings.
It's cheap, I think it will work, but I would call it a tremelo, because.. that is what it is.

Is it safe to have such a circuit connected to my guitar and amp without caps on the circuit's input and output?

The French Cookbook also has a 3 transistor version that looks better, but I don't think it's a vibrato either. Perhaps I should just go with the Wobbletron from circuit snippets.

That's the 3 transistor "vibrato"
http://partouze.chez.tiscali.fr/stomp/3tranvibrato.jpg

Ge_Whiz · January 14, 2005, 08:32:37 PM

Quote from: bobbletroxIs it safe to have such a circuit connected to my guitar and amp without caps on the circuit's input and output?

Perfectly safe if you wire it up correctly, although capacitors would safeguard your guitar and amp from the battery. It's just acting like a crude variable volume pot.

hair force one · January 16, 2005, 09:05:23 AM

everithing that's called 'vibrato' in this book is in fact tremolo ...

News:

French Cookbook Vibrato.