beginner, info needed and transistor question

[Upspoon]

Hello everyone,

As a guitar player, and an avid tinkerer i found my way into the awesomeness that is building your own guitar pedals. I want to get into designing new ones as well and i suppose this is where the tinkerer comes out. I only have basic knowlege about building circuits, if anyone knows any literature in regards to circuit building in relation to stomp boxes, down to a very beginner level, i would greatly appreciate being pointed in the right direction.

Having said that, as a first build, I have put together an order for the AMZ mosfet boost pedal, its simple and has a small amount of components and i figured this would be a great starting place.
My question is regards to this is, i have obviously purchased the mosfet transistors for this thing, i have also come across some ac128 transistors (a matched pair) and wondered if one or both of these could be used in this boost pedal (i know these are used more in fuzz boxes). I'm looking for a more transparent boost, but don't mind if it adds a little flavour.


Thanks for your time!

[midwayfair]

Well, the "matched pair" is matched for some specific circuit, most likely a fuzz face. I'd save them to build one of those.

Chances are you could just plug one in, in place of the MOSFET, with some small adjustments to the resistor where the drain of the MOSFET would have gone. Pay attention to the pinout. It will be noisy, because germanium transistors have leakage, which produces a hissing sound if the leakage is high. It won't be as loud. You'll have to swap out the Zener for a germanium diode to protect the transistor from temperature drift. To use both, you could create a Darlington pair. This will have more gain, probably closer to what a MOSFET can put out, because a Darlington pair multiplies the gain of both transistors used -- but it also multiplies the leakage. So even if you have two good, low leakage transistors, you could end up with a VERY noisy box. Not really worth it in my opinion.

[gjcamann]

THere's a few different types of tranys. MOSFET is one type, you can usually swap MOSFETs with other MOSFETs in the same circuit. Another type is Germainium, and you can swap Germaniums with other Germaniums, but may need to tinker with the circuit a little. If you're a smart dude  you can probably get a Ge to work where a MOSFET was with suffecient circuit changes. But for a Noob, I suggest saving your AC128's for a future Fuzz Face build. If you want to have some fun with the AMZ boost, I suggest you try making a SHO http://hotbottles.wordpress.com/2012/03/29/building-a-z-vex-sho-clone-from-scratch/ or try adding some clipping diodes to ground to make an Electra Overdrive (You can even switch them in and out to give you clean,dirty boost).
Good Luck,
George

[Kipper4]

Try making the zvex SHO Super hard on. An NPN Fuzz face or even a DOD 250 all of which should be within your ability. What about a Treble booster?
Have fun and enjoy it.
I too only took this up last xmas holiday and i'm starting to hack and make my own designs. They're not good yet but i learn something new with every circuit. Usually how patient i am against how patient i need to be.
I love it i wished i'd done it years ago.

[artifus]

breadboard.

[Upspoon]

awesome thanks for the replies everyone.

Thanks pretty much what i figured about the transistors, but thats definitely the tinkerer coming out in me.

For the boost pedal i exchanged the correct resistor for a trimmer to allow me to easily adjust the leakage i beleive of the mosfet

The sho definitely looks interesting. And adding a switchable dirty boost to this pedal sounds like an awesome idea too.


The long run idea is that a buddy and i want to start designing pedals and while i have a fair general knowlege and the ability to put things together, The understanding of circuits and how they work still eludes me. I've been trying to track down some literature in regards to this.

This is definitely a hobby to stay for me though, as i'm already hooked. haha.

[Kipper4]

Read up some of R G Keens stuff like Anatomy of the Tube screamer. (google it) you will have a better understanding of componant parts of a circuit board.
Theres a shed load of good info here too to wade through. Dig in and one article leads to another until the brain goes to mush and you (rather I) cant take anymore in.
Good luck with your venture. and welcome to the forum btw.

[duck_arse]

what artifus said.