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I have been playing around with this circuit for awhile now, but finally have finished the pedal. A veroboard special. This fuzz is powered by a single AA battery (in the old days this was called a Penlight battery).
The graphics were inspired by the first two Grand Funk Railroad album that featured Mark Farner’s Messinger Guitar with a built in fuzz/distortion circuit which Farner called the “Tone Messer.” I did quite a bit of research over the past couple of years to try and build the circuit as accurately as possible. From photos and schematics I found on the internet, pretty much everything in the circuit has been figured out except for the capacitor values as there are no good pictures of the caps. Early on in discussion of the circuit a Mystery Component is found on the board, which was later deduced to be an Inductor or Choke for RF Interference Rejection. The estimated Inductance of the RF Choke was thought to be probably 1uH to 10uH. The basic schematic is below.
To make the fuzz more versatile, I decided to add a Tone Control (variable input capacitance) which could be defeated to the stock Input Cap value (thought to be 100n). In addition, I decided to add a Volume control, which also could be bypassed to the Output cap (thought to be 1n). I chose not to put in a Gain Control as the Volume Pot of your guitar works fine for this purpose, although I did experiment with a B250K pot at the input of the circuit, which worked fine for that purpose and something someone might want to add to the circuit. I chose a A1M pot for the Volume Control matched with a 10n Output Cap. I was having trouble with this until Wilkie (may he RIP) graciously chimed in that the volume pot was acting as a High Pass Filter configuration which was taking away some of the lower frequency content as the volume was turned down. Using a higher value Output cap and higher value volume pot helped with this problem, with loss of high frequence content near the lowest end of overall volume, which likely wasn’t going to be something I would do with the output volume anyway. My final schematic is below.
I initially paired a B100K pot with 4.7nF and 2.0uF capacitors (2 x 1uF non-electrolytic in parallel) but the results were not as what I was expecting, so I change the Tone Control to a A500K Pot with 2.2nF and 2.0uF capacitors, similar to the tone control of a Naga style Treble Booster. This allows one to compensate for the loss of low end content using the volume pot, if need be, or to just get the tone close to the early GFR guitar tone. My final Vero layout is below.
Finally, wiring up the pedal was not all that difficult, although the two SPDT switches for the Volume and Tone bypasses made it a little more complicated. The final wiring diagram is below.
As a last comment, I first used fairly high gain NPN 2N5088 transistors of around 475Hfe, which gave a great fuzz, but very little octave effect. It was suggested in one forum that the original transistors appeared to be Fairchild 2Nxxxx in a small button head (TO-106) package, probably 2N3565. The old (NOS) 2N3565 were known to produce a slight octave effect in a pedal. So I obtained a few of these from Small Bear. The two highest Hfe transistors paired together (~300Hfe and ~350Hfe) produced way too much fuzz and noise. The lower gain ones (~240Hfe and ~260Hfe) paired together produced less fuzz and more overdrive/mild distortion. Pairing the ~260Hfe and ~300Hfe transistors provided that ratty sounding fuzz, with an octave component up the neck similar to the Green Ringer. Therefore, there was no need to add the Green Ringer into the mix.
Gutshot of the finished pedal.
I provided all this information in case someone wanted to get adventurous and build something similar with or without all the modifications.
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