2N3904 replacement for Millennium Bypass 2?

[pappasmurfsharem]

Oooh Noesss!

I can't find my bag of 2N3904's!

Is there any suitable replacement for use as a Low Leakage DIODE? or would there be a diode I could use perhaps.?

I don't have anything fancy just your 99% standard transistors 2n5088 5089 3906 2n7000 2n2222 others....

Does pretty much any NPN work?


I'm an idiot I swear i've read this numerous times....

For anyone that happens across this thread....http://www.geofex.com/article_folders/millenium/millen.htm

I must get four or five questions a month from beginners who want to build the Millenium and will not read the whole article. Do not use any old diode as a "low leakage diode". Use the collector-base junction of an ordinary small signal NPN transistor. This junction is intended by design to be low leakage in all modern transistors. A good example is 2N3904, 2N4124, 2N4401, 2N5088, etc. If you can't get 2N transistors, use what you can find. Any BCxxx series NPN will work, as will any 2SCxxxx series small signal device. Get yourself the easiest to find  NPN small signal device (TO-92 package is ideal), cut off the emitter lead at the plastic, and use the resulting C-B junction for your low leakage diode.

[armdnrdy]

I was going to throw in this:

When the effect is bypassed (LED off) we want the bipolar transistor to turn on. When it's on, the transistor looks like a low resistance to ground, maybe under 50 ohms for garden varieties of transistors, as low as 2 ohms for some specialized ones.

[R.G.]

When the effect is bypassed (LED off) we want the bipolar transistor to turn on. When it's on, the transistor looks like a low resistance to ground, maybe under 50 ohms for garden varieties of transistors, as low as 2 ohms for some specialized ones.

Actually, no we don't. The bipolar transistor is used ONLY as a diode - the emitter lead is clipped off, or could/should be. The low leakage diode is an afterthought, and only there as a protection for the MOSFET in the Millenium 2. The Mill 2 works without it. Better in fact, at least to the degree that the diode leaks.

I have had more correspondence on the low leakage diode (what is that? what kind is it? what number? what do I do with the other lead? what transistors work? can I sub in a light bulb or a garden hose? will a resistor work? what if I leave it out? ...) than on any other aspect of the Mill 2 except perhaps the LED being on all the time from getting the MOSFET inserted backwards.

Sometimes I wish I'd left it out and just dealt with the many fewer questions from the rare times people killed the MOSFET.