Schematic for weird vintage homemade fuzz box found on eBay.

Rambozo96 · Post by **Rambozo96** » 16 Aug 2020, 16:32

Found this oddity on eBay with a schematic taped to the unit.

Rambozo96 · Post by **Rambozo96** » 16 Aug 2020, 16:35

Here we go, helps to actually attach the schematic

toneman · Post by **toneman** » 16 Aug 2020, 19:41

some kind of FF? what's the case look like?

OC26 · Post by **OC26** » 17 Aug 2020, 11:14

Definitely Leo Fuzz Box

http://guitar-fx-layouts.42897.x6.nabbl ... 11522.html

lolbou · Post by **lolbou** » 17 Aug 2020, 21:06

Is it dipped in some kind of resin?

soulsonic · Post by **soulsonic** » 18 Aug 2020, 04:50

Tagboard layout with mustard caps, for the hipster love.

P.S.
Please don't link to schematics off-site. Download it and re-upload here. Especially if it's old shit like this where the "original" poster obviously don't own it. FSB is one of the only continually permanent schematics archives of the past 10 years. All this outside crap disappears in a year and we get stuck with all these lame dead links.

rockola · Post by **rockola** » 19 Aug 2020, 09:31

I redrew the schematic (with C2 that was missing) and added modern accoutrements (LED, power protection/filtering, true bypass). Also laid out the board, which can be built in the original configuration (but if you're looking for historical accuracy you're probably going to want to etch your own PCB anyway). Not verified but will get some done by Oshpark shortly. The KiCad files (note: drawn with latest nightly) are at https://github.com/rockola/leo-fuzz-box

Looks like this was already discussed in 2011: viewtopic.php?f=1&t=14035

mictester · Post by **mictester** » 23 Aug 2020, 03:14

Your C2 is in the wrong place. It should be in series with the wiper of the pot. It's worth experimenting with the value of C2 - 1n (as recommended) gives a thin, reedy tone. Increasing it brings you towards Fuzz Face territory, though with a different edge to the sound. The 68k and 10k resistors at the output can be replaced with a 100k preset, wired as a volume control. If set correctly, the "normal" mode gives a little bit of gain, and the "fuzz" mode is at the same output volume.

There are numerous other modifications that can be made to this simple little circuit. It's worth adding "C4" - a 47µ or 100µ to the "normal" side of the power routing switch. This eliminates switching "pop" noises.

rockola · Post by **rockola** » 23 Aug 2020, 17:42

mictester wrote: ↑23 Aug 2020, 03:14 Your C2 is in the wrong place. It should be in series with the wiper of the pot.

IOW, before the Fuzz/Normal switch? It's in series with the wiper when the switch is in the Fuzz position, isn't it?

mictester · Post by **mictester** » 24 Aug 2020, 03:05

It goes between the wiper of the pot and the common of the switch. When in "Fuzz" mode, the capacitor is connected to the junction of the output resistors. It stops the bias of the transistors being changed as the control is rotated in "Fuzz" mode, and also applies a measure of feedback filtering.

It's a great little circuit and some players in the late 60s / early 70s preferred it to the Fuzz Face. Back then, I made dozens of them!

rockola · Post by **rockola** » 24 Aug 2020, 07:51

mictester wrote: ↑24 Aug 2020, 03:05 It goes between the wiper of the pot and the common of the switch.

Gotcha. Already ordered some boards but that's easy enough to fix off-board. Like this then?