Tremolo

[Arthur Harrison]

The two points marked "Vs" are the supply voltage.  
(It would've been nice if that voltage was specified, 
but let's assume that it is +9v.)  Hopefully, the phase-shift
oscillator will work correctly at this voltage.  

The point  marked "+Vs/2" is one-half of the supply voltage.
Although not shown in the schematic, this may be obtained with
a two-resistor voltage divider, the top of which connects to Vs
(pin 4 of the quad op-amp package) and the bottom of which 
connects to ground (pin 11).  Use 100k resistors, and connect
a 0.1uF ceramic capacitor in parallel with the lower resistor.

This technique may be quite distortion-prone compared with
a resistive cell or Gilbert core. Some guitar pick-ups produce 
more than a volt, although this circuit may present too low a load 
impedance for the pick-ups, anyway! 
 
Be sure to commit the unused op amps.  A LM358, BTW, is 
a dual version of the '324 quad op amp.  The dual would be a 
better choice, for the sake of lower power consumption.

Art
Pages: http://home.att.net/~theremin1
Email:  theremin1 at worldnet.att.net

------------------------
  
>But I don't think I understand it.
>It has three points, two labled eiter "V5" or "Vs", not sure which. And
>another labled "+V5/2" or "+Vs/2"
>
>Can anyone help? I don't mind a little noise.
>
>Mark