Bipolar Substitutes

[Faber]

Okay, while I have some free time, I want to compile a list of Bipolar substitutes and putting it online for everyone's use.  I read the wiki about R.G.'s substitution laws and thought a list might be useful.  I have but one problem:

I'm not exactly sure what matters when you look at a datasheet.  I want to get the numbers for the stuff that matters, compare them and have those on the site so people can see it.  Obviously the maximum ratings and hFE, but I'm stumped besides that.

If someone could help me out, or point to something that has already been done, the help would be greatly appreciated.

I want to do my part to help out the world of DIY FX.

Thanks,
stephen

[R.G.]

Good motivation. If you want to do the detail work, that's good.

What matters in effects circuits is:

BVceo >16V ; this comes from the need to be bigger than the nominal 9V power by a good margin. This is NOT enough for pedals powered by higher voltages like 12V/18V or even 24V. Ordinary Univibe transistors should really be more than 30-35V because of the unregulated power supply in the stock version. But for 9V pedals, 16V is OK.
Icmax > 10ma ; works for all signal circuits that are not also line driver or maybe LED driver devices. In that case, go for 100ma.
Hfe >100; This is big enough to make the standard approximations for gain work out fine.  For low noise signal circuits, you want more. Unless there is a special reason, you want hfe>300;
Noise figure; the lower the better. 2db is OK.
Pd (power dissipation) > 100mW. This is pretty much fixed by the mechanical package size, and the stockTO-92 is good for 500-800mW in almost all cases. This really only applies for high current applications like LED driver, speaker or line driver, maybe a special regulator circuit.

That's about it. No current production silicon device is slow enough (i.e. ft is low enough) to worry about in audio circuits by several orders of magnitude. MOSFETs and JFETs are usually even faster.

It becomes difficult to find a device that will NOT work in most circuits if it's the right polarity.

[Faber]

Okay, I'm looking at a 2N3904 datasheet and the light bulb is slowly coming on...

Thank you, R.G. and if I have any more questions then I'll post them.