It's only a stupid question if you already know the answer. Many
students have failed classes because they didn't ask what they thought
was a stupid question.





On Thu, 19 May 2011 18:14:09 -0500, "Dave" wrote:


"Dave" wrote in message
news
Am trying to bias the JFET in the attached schematic to feed signal to the
following BJTs while keeping Vgs very near Pinch-Off. Works fine as long
as the batteries are fresh, but as they begin to wane Vgs surpasses
Pinch-Off (which is 4.0 volts for the JFET I am using, while I try to hold
it at 3.95 VDC.) It has been suggested that I use a BJT (configured for
Common Emitter) to do this, but I am in the dark as to how this might be
accomplished. ANY help would be greatly appreciated...

Thanks,

Dave




Okay, Murphy's Law rules. Was effecting a minor change in the biasing of
the JFET and when I hooked it all back up I let +12VDC hit the varactor D4
out of utter carelessness and too much wire where it wasn't needed. Now all
my varactors are blown and I may have damaged one or more transistors. Will
be back later after I have sorted all this out.

JT: Thanks for the input on the source resistor, but the NTE451 apparently
limits Id to 3mA by itself (much to my frustration). I don't need to do
that for it. What I do have to do is work with the 3mA it allows.
Anyway, I appreciate your input and may be back later if what I was trying
doesn't work to my satisfaction.

Thanks.

Dave