MOSFET Boost/Overdrive (And AArdvarks!)
Posted: Wed Oct 06, 2010 8:53 am
UPDATE
I deleted the old stuff. This is better, which is why it's here instead.
This is the final version. I'm not gonna change it any more. It's basically a MOSFET Electra Distortion. (which itself is just a booster with clipping diodes).
The toggle switch has 3 positions. In the middle, the pedal mostly functions as a booster (but you'll get some distortion with the gain control up). The right position (if wired so it looks just like the layout) would send all of the signal to the clippers, while the left is a "bass" mode that leaves some lower frequencies untouched.
The parts going to ground are shown going to the back of the pots. Don't solder to the back of the pots unless you have a fairly powerful (40 watts+) soldering iron with a big tip, and be sure to prep right-- sand the pot where you're gonna solder, and use a bit of liquid flux. The reason is that the wiper in the typical pots used in pedals is made of plastic and will melt very easily.
For bypass switching, I recomend taking a look at GGGs wiring page. Choose what you want.
I left the traces larger than I normally would, because some may be hard to see. If you have any questions, yeahh.
Mods:
The clipping diodes (Q2 and D2) could be replaced with basically anything. For something easier to wire, replace the BS170 with a 1N914 (or similar). It won't sound just the same, though. If you can't find BAT42s, any schottky would work, basically. BAT42s are usually pretty cheap at Mouser.
Some MOSFET boosts use higher value bias resistors. The Super Hard-On uses 10M, which are only really available in carbon film. The And AArdvarks! has pretty low input impedance, so using such high values doesn't help. You can raise them if you want to, but you probably won't get much extra out of it, since the bias voltage is always going to be 1/2 the output voltage + drain voltage. If you want a hi-fi sorta boost, I recommend trying out Jack Orman's MOSFET booster instead.
I deleted the old stuff. This is better, which is why it's here instead.
- And Aardvarks!.jpg (122.88 KiB) Viewed 3366 times
This is the final version. I'm not gonna change it any more. It's basically a MOSFET Electra Distortion. (which itself is just a booster with clipping diodes).
The toggle switch has 3 positions. In the middle, the pedal mostly functions as a booster (but you'll get some distortion with the gain control up). The right position (if wired so it looks just like the layout) would send all of the signal to the clippers, while the left is a "bass" mode that leaves some lower frequencies untouched.
The parts going to ground are shown going to the back of the pots. Don't solder to the back of the pots unless you have a fairly powerful (40 watts+) soldering iron with a big tip, and be sure to prep right-- sand the pot where you're gonna solder, and use a bit of liquid flux. The reason is that the wiper in the typical pots used in pedals is made of plastic and will melt very easily.
For bypass switching, I recomend taking a look at GGGs wiring page. Choose what you want.
I left the traces larger than I normally would, because some may be hard to see. If you have any questions, yeahh.
Mods:
The clipping diodes (Q2 and D2) could be replaced with basically anything. For something easier to wire, replace the BS170 with a 1N914 (or similar). It won't sound just the same, though. If you can't find BAT42s, any schottky would work, basically. BAT42s are usually pretty cheap at Mouser.
Some MOSFET boosts use higher value bias resistors. The Super Hard-On uses 10M, which are only really available in carbon film. The And AArdvarks! has pretty low input impedance, so using such high values doesn't help. You can raise them if you want to, but you probably won't get much extra out of it, since the bias voltage is always going to be 1/2 the output voltage + drain voltage. If you want a hi-fi sorta boost, I recommend trying out Jack Orman's MOSFET booster instead.
- And Aardvarks!.jpg (122.88 KiB) Viewed 3366 times
