"Miss piggy" schematic link anyone?

Started by John Lyons, February 06, 2007, 10:48:57 AM

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John Lyons

Can someone point me to the "Miss Piggy" schematic. I can't find a working link in a search...
Curious how this piggybacking transistor thing works.

Thanks

John
Basic Audio Pedals
www.basicaudio.net/

markm

I've been looking for this myself......

mattpocket

I wanted to find out about this too, can someone explain it, I'm not as clever as these guys above...

What does it do again? haha my minds gone blank!
Built: LofoMofo, Dist+, Active AB Box, GGG 4 Channel Mixer, ROG Omega
On the Bench:Random Number Generator, ROG Multi-face, Speak & Spell
--------------------------------------------
My Pop-Punk Band - www.myspace.com/stashpocket

puretube

the "piggybacking"-search is your 3 page friend  :icon_wink: :icon_wink:

petemoore

  We look at Q1, FF.
 a second Q is paralleled, E/E, B/B, C/C.
 This reduces gain of the 'transistor' [actually two transistors, the circuit 'sees' only one because theyr'e piggybacked.
 Then a resistor or pot is used between the Emitters, to reduce the gain reduction effect, or to reduce gain, but to a lesser degree, something like 10k...I would exp with Qs and second' emitter resistance.

             C    /    C
 Input    B    /    B
            E           E
             Resistor
 And nicely packs an 8 pin IC socket, the bottom two R/L pins used as a resistor socket or use a pot there to adjust the R which adjusts the gain of the 'transistore'.
 The same can be done for Q2, but it's easier to find a not so low gainer Q2 transistor for FF.
 Brett is the Piggyback schematic guy IIRC.  
Convention creates following, following creates convention.

John Lyons

Ok, thanks for the explanation Pete!
I searched for it but I'll have to search under "piggybacking"

John
Basic Audio Pedals
www.basicaudio.net/

petemoore

  IIRC it was Brett did a bunch of work on that...?
Convention creates following, following creates convention.

slacker

I've got the schematics, I'm going to ask for brett's permission to post them. If anyone wants them in the meantime PM me.

slacker

Got the OK off brett, so here's the Miss Piggy schematics, I downloaded them a while ago so I don't know if they're the latest verions.




marlin

Does anyone have a stripboard layout ready for it?  (yes i feel a bit lazy)  ;D

brett

Hi
That Miss Piggy V3 is quite close to what I'd suggest is a good build, except:
1.  the 2.2uF cap is too large for the fuzzface IMO.  0.47uF makes more sense electronically and musically IMO.
2.  for Q1/Q2, the 10k "piggyback" resistor should be reduced to 3.3k or 4.7k (thereby reducing the hFE of Q1/Q2)
3.  to filter some un-harmonic highs, bypass the 330 ohm resistor with 0.033 to 0.068uF (as done in the popular Axis Face)
cheers
Brett Robinson
Let a hundred flowers bloom, let a hundred schools of thought contend. (Mao Zedong)

mac

• As the collector is unconnected, would a diode and a resistor from base to emiter do the trick (no second transistor)?
• What if the 2nd collector is connected?
• What about a diode or resitor between the bases and/or collectors?
• ...

It seem that old Arsenio Novo's distortion circuit is just like Mr. Fozzie Bear :icon_mrgreen:

mac
mac@mac-pc:~$ sudo apt-get install ECC83 EL84

Cozybuilder

#12
Reviving an old one here! I spent a bit of time chasing dead ends, and finally contacted Brett Robinson, who sent the schematic for "Miss Piggy V3". (Do a search for photos) This is one result of some very interesting work done by Brett and RG to lower the gain of Silicon transistors to give a more Germanium type tone.

Thank you Brett!!

Some people drink from the fountain of knowledge, others just gargle.

aron

I never got around to this one. Need to check it out.