2N2222's

[CodeMonk]

In the process of building a Fuzz box.
It uses a 2N2222.
So I go into Radioshack the other day to buy the parts. Got everything there.
Yeah, I know, RadioShack is overpriced, but locally, I have no other options.
Anyway, I look in the bin, and grab a 15 pack of 2N2222's
I get home and crack open the package, and inside there are 2N3403's instead of 2N2222's
Are the 2N3403's compatible with the 2N2222's?
Will they work or will I get smoke or crappy sound or what?

Thanks.

[Dragonfly]

Its a "functional equivalent".

It will likely sound a little different than the 2N2222, but that could be "good" or "bad".

Use sockets for the transistors and swap till you find a sound you like.

Oh...and welcome to the forum !

[GREEN FUZ]

What goes round...

http://www.diystompboxes.com/smfforum/index.php?topic=11744.0

Oh...and welcome to the forum !

+1

[CodeMonk]

Thanks Dragonfly.
the one I am building is the Jordan Bosstone (from your site I think).
BTW...love your painting on those boxes.

[iaresee]

Its a "functional equivalent".

Just trying to get a better understanding of how to decide it's okay to swap transistors. I looked at the data sheets and they didn't look interchangeable because the 2n3403 is lower power, lower current than the 2n2222. Is the current always low enough in all pedals to make the trade off? Or am I looking at the wrong things to decide when I can do a swap?

[Barcode80]

you are looking at the wrong things. as long as they are both of the same configuration (NPN or PNP) you can switch out transistors endlessly. whether or not gain, power, etc. matter depends on your ear and the circuit.

[iaresee]

you are looking at the wrong things. as long as they are both of the same configuration (NPN or PNP) you can switch out transistors endlessly. whether or not gain, power, etc. matter depends on your ear and the circuit.

I would have thought pushing the 800 mA max current that a 2n2222 can handle through the 2n3403 wouldn't be a good thing. I've never fried a tranny before -- does it take more than that? I doubt there are many fuzz pedals out there pushing close to an amp, but is that really true of all pedals? I mean, to really be a safe substitution, what do I have to consider?

[Barcode80]

You are not going to be pushing 800mA through anything. a HIGH current draw through a pedal is roughly 30mA. maybe as high as 50mA. most fuzzes run at about 15 to 20mA.

[idlechatterbox]

Everyone has a different take on the work ethic, so I don't mean to speak with any authority... but for me the "will it work" tolerance is pretty wide with DIY pedals. Sometimes the best way to know if you "can" substitute transistors (or any other component, within reason and the principles of physics) is to try it. Sometimes there's a sound difference, and sometimes it's one that you will like. I had one vero board that had a trannie installed in its socket backwards. It sounded great, and I only noticed it months after I'd been using it that way. Not recommending that, but it shows that sometimes your ears (not someone else's, and not a schematic) are the best judge of what works. Again, there are some rules you can't really break, but in terms of substitutions, there's a lot of elbow room. I'm not sure if it's still around, but there used to be a project called the Socket-face that was designed around the idea that you could test out all kinds of substitutions in the caps and trannies. I socket all trannies and nearly all caps. Sockets are cheap, and you can make them easily from IC sockets if you don't want to buy the "real" ones. Admittedly, that often leads to a bit too much tinkering to see what happens with a slightly different value component, but that problem just leads to hours of tone experiments, and I'm not sure that's so bad. Good luck either way.   

[Gus]

People use ohms law to help figure out current drain or use a DMM in current setting to measure it.

15 to 20 ma in fuzzes?

Most of a FF type current draw can be calculated via the voltage drop across the collector resistors and added together.  In a FF type say 10K collector resistors total at Q2, 4.5VDC / 10K =about .45ma.  Do the same for Q1 voltage drop across the collector resistor / resistor value,  then calculate the current in the LED leg then add them together.

If you use a 100 ohm and a cap from the battery the voltage drop across the 100 ohm / 100 = the total current draw. 

[DougH]

15 to 20 ma in fuzzes?

Yeah, really... That sounds like an output section in a small tube amp.

New project idea: I need to build a power substation for my pedal board.

[brett]

Hi
Gus' idea of using a 100 ohm resistor in-line with circuits (before the usual cap-to-ground filter) is a good one for another reason.  It provides a low-noise voltage supply.  A filter consisting of a 100 ohm resistor and a 47uF cap have a cutoff frequency of 32 Hz, which means that hum (60 Hz or 50Hz), and most other "rubbish" on the line are suppressed quite well.

2 birds with one stone.   
cheers

[Barcode80]

heh, actually i undershot it, as i meant to put a "." before those numbers

[CodeMonk]

Ok well, I finished the Jordan Bosstone.
The 3403 trans either was not compatible with the 2222 or was dead because it didn't work. No sound.
I went back to Radio Shack and grabbed a pack of transistors. There was a 2222 in there.
I plugged it in and lo and behold, it worked.
Not 100% satisfied with the effect (It sounds OK, but not exactly what I was looking for), but thats another story.

[GREEN FUZ]

I believe the reason the 3403 doesn`t work is that its pinout is different to the 2222.

[CodeMonk]

Ahh...Damn, why didn't I think of that (or even look).
Been a long damn week here.

Thanks