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previous: Peter Re: tiny tripple bypass question -- 6/14/2000 10:40 AM

Getting the triple bypass to work

6/14/2000 1:09 PM
R.G.	Getting the triple bypass to work If you're trying to get this to work, use three PNP transistors, and reverse the polarity of every other polarized part in the diagram. The "triple bypass" is a three-stage darlington to get enough current gain to get the popping down. As to the Millenium Bypass - the high leakage diode is a 1N914 or 1N4148. These are gold-doped to speed up switching on and off in the diodes. This has the side effect of causing them to leak a lot (for silicon!), maybe as much as 10-15nA. A "low leakage" diode is just a silicon diode that is NOT specially doped. The collector-base junction of any ordinary silicon transistor makes a fine one. I use the CB junction of 2N3904's in mine. See the illustration in the newest article on the Millenium 2 at GEO. P-channel MOSFETs can be had for about $0.50 -0.75. Gotta pick the right source. They do cost more than three transistors - but they work... And you have absolutely the right attitude on mistakes!!! Go for it!

6/14/2000 1:09 PM

R.G.

Getting the triple bypass to work

If you're trying to get this to work, use three PNP transistors, and reverse the polarity of every other polarized part in the diagram. The "triple bypass" is a three-stage darlington to get enough current gain to get the popping down.

As to the Millenium Bypass - the high leakage diode is a 1N914 or 1N4148. These are gold-doped to speed up switching on and off in the diodes. This has the side effect of causing them to leak a lot (for silicon!), maybe as much as 10-15nA. A "low leakage" diode is just a silicon diode that is NOT specially doped. The collector-base junction of any ordinary silicon transistor makes a fine one. I use the CB junction of 2N3904's in mine. See the illustration in the newest article on the Millenium 2 at GEO.

P-channel MOSFETs can be had for about $0.50 -0.75. Gotta pick the right source. They do cost more than three transistors - but they work...

And you have absolutely the right attitude on mistakes!!! Go for it!