SMT Fuzz Face

[beans_amps]

Hey all,

A couple years back I made up a Fuzz Face (maybe actually a Sili Face) in SMT.  This started because I accidentally ordered some MMBT2N5088's by mistake.  I also wanted to make a pot mounted effect.  Alas, It did not sound good to me; too fizzy.  But I thought I would post it and see if anyone was interested.  The whole thing is 1" (25.4mm) square and is held by the solder logs of the volume pot.  The tone pot can either be mounted on flying leads or replaced by fixed resistors.  There is a provision for a trimpot on the input a la Mike Fuller.  You can jumper the pot connections if you do not want to try this option.  I did not incorporate the 1K pot before the output and chose to use a 10K in place of the 8.2K.

I recently ran across this and thought I might give it another go with some lower gain transistors.  I found some Germanium SOT-23 transistors bu they are all intended for RF work and may not sound good.  I have not yet tried any to find out. 

I might could jam this onto a 0.5 inch board but I am too lazy.

p.s.  Anyone have any one knob builds that could be "pot mounted" they might want to see done the same way?

http://www.angelfire.com/mech/beansamps/layouts/micro_face.pdf

Sean

[beans_amps]

I just realized that I did not explain that the smaller image is actual size while the larger one is 2x magnified.  Also I forgot to turn off the components before plotting the image.

Sean

[Nasse]

Anybody tried "piggyback" technology in smt ff? I am getting old, I need to buy magnifying glass

[Sir H C]

Are those RF transistors SiGe?  Silicon Germanium?  If so, they are not very suited for a fuzz face.  Very high thresholds (~1.2 volts) and very fast so prone to oscillation.

[beans_amps]

I went back and checked the maufacturers data sheet and they are indeed as you thought.  I was afraid to use try them anyway because the GBW on these is 12GHz.

Could be prone to oscillation. 

I am going to look into the piggy backing thing.  I have neverinvestigated or tried it.

Sean

[sfx1999]

You can use a 50-200 pF resistor to eliminate RF. Just put it from the base to the emitter of your transistors.