Author Topic: 7min Fuzz - alterations (DIYGuitarPedals)  (Read 170 times)

tehmessiah75

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7min Fuzz - alterations (DIYGuitarPedals)
« on: August 02, 2017, 06:53:38 PM »
As Paul from GIYGuitarPedals is taking care of his family (Family First mate, best of luck to you and your son) I'm asking here for some assistance.

I bought Paul's 7min Fuzz and I want to incorporate it into a combination pedal that's running off of 12 volts.
It's a 12au7 Tube boost & distortion pedal that requires 12v.

7min Fuzz Schematic http://www.diyguitarpedals.com.au/shop/boms/7_Min_Fuzz_Schematic.pdf

So I roughly calculated that for the 7min Fuzz to work on 12v I need to increase the voltage of R1 (10k Ohm) to a 12k or 13k ohm resistor?
Can someone with better electronics knowledge confirm this please?

Also I only have a 50k Ohm Audio pot will this be ok for the Volume control?
His circuit requires a 100k Ohm Audio pot.

Fabei

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Re: 7min Fuzz - alterations (DIYGuitarPedals)
« Reply #1 on: August 03, 2017, 08:03:11 AM »
As Paul from GIYGuitarPedals is taking care of his family (Family First mate, best of luck to you and your son) I'm asking here for some assistance.

I bought Paul's 7min Fuzz and I want to incorporate it into a combination pedal that's running off of 12 volts.
It's a 12au7 Tube boost & distortion pedal that requires 12v.

7min Fuzz Schematic http://www.diyguitarpedals.com.au/shop/boms/7_Min_Fuzz_Schematic.pdf

So I roughly calculated that for the 7min Fuzz to work on 12v I need to increase the voltage of R1 (10k Ohm) to a 12k or 13k ohm resistor?
Can someone with better electronics knowledge confirm this please?

Also I only have a 50k Ohm Audio pot will this be ok for the Volume control?
His circuit requires a 100k Ohm Audio pot.

50k Ohm is fine for the volume pot.
For the tranny, consider that here is poorly biased on purpouse to achieve the fuzzy tone so I THINK you can leave it that way or better subs it with a trimmer to find your "spot". Consider a breadboard too, it's the fun part :)

tehmessiah75

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Re: 7min Fuzz - alterations (DIYGuitarPedals)
« Reply #2 on: August 03, 2017, 05:16:33 PM »
Sweet, thanks Fabei.
I'm using his germanium fuzz mod as well so hopefully this will be awesome.

On another note.
The LED current limiting resistor, all guitar pedals seem to have 2k2 - 4k7 ohm CLRs. However most places only recommend a 510 ohm (max, depending on the LED Specs) resistor for 12 volts.
Why do guitar pedals use such a high resistance?

How/where would I add a tone pot to the circuit and what size cap would I use for it?

somnif

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Re: 7min Fuzz - alterations (DIYGuitarPedals)
« Reply #3 on: August 03, 2017, 05:22:10 PM »
The LED current limiting resistor, all guitar pedals seem to have 2k2 - 4k7 ohm CLRs. However most places only recommend a 510 ohm (max, depending on the LED Specs) resistor for 12 volts.
Why do guitar pedals use such a high resistance?

Largely because using really low resistances results in a ridiculously, painfully bright glow. The 510 ohm you mentioned is what would be the bare minimum to get the max running current across the diode. It will work. It will also light the whole damn room. We use lower values so that we can actually look at the pedal while it is operating. Some diodes use quite low values, others quite high. I use down to 1k or so for diffuse red LEDs. I use up to 33k for waterclear superbright blue and white LEDs.

I recommend testing your LEDs with a breadboard, or even a few alligator clip leads, just to check that its glowing at a level you find pleasing.

tehmessiah75

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Re: 7min Fuzz - alterations (DIYGuitarPedals)
« Reply #4 on: August 03, 2017, 05:48:46 PM »
Thank you somnif.
I'll have to make a few adjustments then.
I bought 510 resistors before doing my research and like an eager idiot I already soldered them into the circuit, then accidentally found some info about it, and the rest is history, unfortunately.
At least I can replace the resistors.

Edit:
I tested the 510 and yes they lit up the room.
I found some 13k and tested them and much better.
« Last Edit: August 03, 2017, 06:52:52 PM by tehmessiah75 »