Tremolo

[Arthur Harrison]

Hi Mark and everyone. Glad to help.
re: http://209.75.211.230/cc/index.htm tremolo circuit.

Re: the photoresistive cell:

There are several ways to use a photoresistive cell as an
attenuator, but the exact application depends on the source
and load impedances.  For your application, I'd have to 
know some specifics about the signal source, including if it 
is directly from the pick-ups or from the guitar's tone and 
volume controls.  

A good starting point would be use an impedance buffer 
following the guitar's stock controls. The buffer's output would 
then feed a tee attenuator with the photoresistor in the stem.  
Then, you may be able to go directly from the tee attenuator's 
output to the relatively high input impedance of a board or amp.

Initially, you can certainly try just putting the cell in series with the 
guitar and amp, since that could work if the impedance factors 
are conducive.  The flashing LED might work, although the 
amplitude modulation might be a little abrupt.  (The photoresistor 
cells do exhibit a highly damped response, usually in the 100s of 
milliseconds, and that will smooth things out a little.)  
  
It is really not hard to modulate the LED linearly; not much more 
complexity than a 555 multivibrator is involved.

I seem to recall Anderton doing a tremolo scheme like this.

The upward arrow does mean "to battery positive."

You wrote: "Is that cap and resister
needed for a 9v battery?"

I am not sure of the cap and resistor you are referring to.

-Art


-----Original Message-----
From: Mark Grocholski <mozepy at earthlink.net>
To: synth-diy at mailhost.bpa.nl <synth-diy at mailhost.bpa.nl>
Date: Friday, October 30, 1998 3:32 AM
Subject: Re: Tremolo


>WOW Thanx everyone!
>
>first: Arthur, thanx for explaining the Vs for me. 
>Now I understand how to use a Pot as an attenuator but how would I do
>this with a photoresistive cell. Just put it in series with the signal?
>Could I just use a flashing LED?
>
>second: tg, those schematics seem pretty easy for me to follow. I assume
>those arrows pointing up all go to +V(9v). Is that cap and resister
>needed for a 9v battery?
>
>In case anyone hasn't noticed I'm still kinda new to this stuff. :-)
>
>Thanks a lot!
>
>Mark
>-- 
>Mark & Carlyn Grocholski
>MOZEPY Productions ><>
>http://home.earthlink.net/~mozepy
>