Fuzz Knob and the elimination thereof

[Somicide]

How would i go about eliminating the Fuzz knob?  I want to put in a switch that way, its either at 50% or Full, and im not sure how.  I'm thinking with a dpdt, yes?  and i'd need a 1k resistor and a 470 ohm resistor, yes?  Or would it be a jumper and a 470?  Sheez... help?

[Peter Snowberg]

I'm assuming you're talking about a fuzz face type circuit here so with that in mind....

Assuming that the fuzz pot is a 1K and you want to hit 50% as an option, you'll need to select two resistors that are each roughly 1/2 of the original pot value. A couple of 470s or 510s or even 560s will be just fine.

* Connect the two resistors in series in place of the element in the pot.

* Connect the cap connection that was going to the wiper to the center terminal of your switch (SPDT).

* Connect one of the switch throw connections to the junction of the two resistors.

* And finally connect the other throw terminal to the other end of the resistor that connects with the transistor.

With the switch in position one the cap is in parallel with one resistor, and with the switch in the other position the cap is in parallel with both resistors. Either way the resistance to ground from the emitter is the same.

If you use a center-off style of switch, the center position will be like turning the fuzz control all the way down.

If you want to ajdust the 50% mark, just select two resitors that added together still give you 1K. For example, if you use a 330 and a 680, you'll get 33% or 67% depending on which resistor is ocnnected to ground.

Happy fuzzing!
-Peter

[brett]

Hi. the idea of replacing the pot on a fuzzface opens up some possibilities for you.  Assuming that you've got a trimpot on the collector of Q2, you can adjust the value of the two emitter resistors down for lower gain or up for higher gain.

For example, 2 220ohm resistors would give much less gain than 2 470 ohm resistors which give less than 2 1k resistors.  (The "Jimi Hendrix" version of the fuzzface had a 2k pot for exactly this reason).

The only hitch is that the trimmer on the collector needs to be able to go to higher resistances in proportion with the emitter resistance.  (for less than 1k total resistance a 10k trimmer, for 2k a 25k trimmer, for 5k a 50k trimmer, etc)

cheers

[bwanasonic]

I've never found any useful sounds with the fuzz knob at anything other than full with my fuzz face. I find the guitar volume knob to be a much better clean/dirty control. If you insist on a switch, I think an SPDT would do? For me, it's easier to twiddle my guitar's volume knob. To me the beauty of the Fuzz Face is the ability to control the effect from my guitar.

Kerry M