What, no discussion? Where is everybody?

Check that last diagram above. Let's say.... just for the sake of argument.... that I LEFT OUT the Black FG output lead altogther from the diagram.
Would it then appear even more magical, if you didn't realize that the FG could act as both a PS and a simple 50R resistor?

(Yes I know that the Ainslie diagram below shows the Q1, and what I am showing is the Q2 behaviour. What the Ainslie -- or rather Donovan Martin diagram is telling you is that the Black FG output lead isn't important, ignore it, don't worry about it, it's just a "negative" and it's grounded anyway so there's no point in including it, or if you do, being accurate about where it is placed. But stay tuned.)



http://www.youtube.com/watch?v=7i0DziLllc0

TK,

That the MOSFET can be "turned on" with
bias applied to the Source is well established.
The technique has been in use for decades;
"grounded grid" in the case of vacuum tubes,
"common base" in the case of transistors,
and
"common gate" as it applies to MOSFETs.

The circuit configuration which utilizes this
form of bias/signal input is generally an RF
Power Amplifier.  The configuration is quite
stable and doesn't require neutralization as
would be the case with common cathode/emitter/
source configurations.

The input impedance is low as all output
current is present in the input signal.

That some of today's "embryonic level"
technicians are not aware of this is not
too surprising.  It's kind of a "niche" circuit
which the 'roll yer own' Hams are very
fond of.

The schematic for Part 3 is the same as for Part 2, but I've changed the Power Supply and am using 2 ea. 12 v, 6 A-H batteries in series instead, with some added lead inductance in the jumper wiring. These batts are pretty low already, they barely measure 25 volts together. And I changed the mosfet: I put in one of Tar Baby's Q2s, including its lengths of wiring.

This video is a bit longer than the other two, and it will be a few minutes before it's viewable.

http://youtu.be/3vm2ZTDUyyA

Quote from: SeaMonkey on July 06, 2013, 12:25:31 AM
TK,

That the MOSFET can be "turned on" with
bias applied to the Source is well established.
The technique has been in use for decades;
"grounded grid" in the case of vacuum tubes,
"common base" in the case of transistors,
and
"common gate" as it applies to MOSFETs.

The circuit configuration which utilizes this
form of bias/signal input is generally an RF
Power Amplifier.  The configuration is quite
stable and doesn't require neutralization as
would be the case with common cathode/emitter/
source configurations.

The input impedance is low as all output
current is present in the input signal.

That some of today's "embryonic level"
technicians are not aware of this is not
too surprising.  It's kind of a "niche" circuit
which the 'roll yer own' Hams are very
fond of.

It's pretty obvious, isn't it, that I know this already. Why don't you log on to Ainslie's forum and tell her this? Since, as you can probably tell from the last posts in her threads there, that she thinks this is impossible, even though it is exactly what her circuit is doing.

Your post, though, with all its extra hard returns, isn't _quite_ long enough to drive my video demonstrations off the front page. It just doesn't seem like your heart is really into your work tonight.

QuoteThe input impedance is low as all output current is present in the input signal.

Got that, Donny? Please explain to Rosemary.

Now, I present to you two schematics. The first one is the one I used in the Part 2 demo above, and also with the 24 v batt in Part 3 above.

The second one is the Ainslie schematic, with the FG lead in the place she uses, and some bits removed and labels changed. Right?

Compare, contrast, discuss.