Bill Gates wrote:
Why does every post griffey does end with LOL????'

Because I can't help but laugh at some of the stupid comments I read
out here. Bottom line... that circuit with those two little doides
isn't doing any temperature tracking for the bases of those
transistors. Several things are wrong:

1.) The bias that feeds those bases needs to be very low impedance...
on the order of around 5 Ohms. There is no freaking way that those
little diodes could carry enough bleeder current to feed those bases.
2.) And if that's not enough... there is another fatal flaw with that
scheme. It's effectively paralleling diodes... the small diodes hanging
on top... and the diodes in the base-emitter junction of the power
transistors. Electronics 101 says that it's a bad plan to parallel
diodes (why you never just parallel bipolar transistors!). The
reason... because one will always hog the current... and starve the
other. One will be on... the other is cut off. You will never get them
both on at one time. Soooooo... when this happens... you can't get any
tracking... because only one diode is on at a time.
3.) Having the sensing on top of the transistors is a poor location.
The internal die is in intimate contact with the heat sink... not the
top! The het sink... preferably near the device is the proper location
for any tracking device.

Like I said before... it's not quite that simple just tacking a couple
diodes on top of the devices... LOL

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