"Joe Davissons PET" problem&schem ?

[MartyMart]

I just made a vero-board layout for this following his schem to the letter
Here it is :
http://www.guitarraonline.com.ar/lapedalera/modulacion/Pet.gif

Its "almost" working but the 1M depth pot "jumps" half way though its travel and is not working correctly, I also have a serious volume loss ?
Anyone built this, or "Joe" was my schem an early/bad "version" or have you an update ??
Thanks for any assistance and sorry for the "vague" info !! :oops:

Marty.

[Joe Davisson]

Try adjusting the collector resistor to make sure the collector is at 4.5v. Also, I dug up the old schem and it shows a 10k audio rate control, and a 1M reverse-log depth control (so, use a 1M audio, it'll just work backwards).

This thing never really did pan out, the EA is probably a better tremolo choice


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[MartyMart]

Thanks Joe, I'll try that  with a trimmer pot on-board.
Would a 1M reverse log taper pot help out, or can I "doctor" my 1M audio pot ... ?
I might try one with a little reduced volume LPB-1 included for some volume recovery
I'd like to get it "right" as the basic sound of it is nice !

Thanks a lot for the design/help

Marty.

[Joe Davisson]

I tried fooling with this a bit, and I don't have any real great ideas for it. There's a constant clicking going on. I ended up trashing the 1M control, the output is already too low.

[Claus H]

I don't think you will get real good results with this circuit.. But I would lose the 1M ohm blend potentiometer put a 100nF cap over the 10k ohm collector resistor and take the output from the emitter resistor, up the value of the 0.022 input cap to 1µF and never use it without a buffer in front of it..  

The volume loss will be arround 6dB

I don't mean any disrespect to you Joe D

Claus H

[MartyMart]

I don't think you will get real good results with this circuit.. But I would lose the 1M ohm blend potentiometer put a 100nF cap over the 10k ohm collector resistor and take the output from the emitter resistor, up the value of the 0.022 input cap to 1µF and never use it without a buffer in front of it..  

I don't mean any disrespect to you Joe D

Claus H

Thank you Claus, very much indeed !!
I'll give that a try  

Marty.