another small breakthrough on our NERD technology.

[MileHigh]

PW:

I just wanted to review the issue of the ground location for the function generator and measuring the battery current flow with you in a bit more detail.  I am under the impression that you view the current going through the CSR as still being indicative of the battery current flow even though you are aware of the fact that current is also flowing through the function generator.  Although I am not so sure you still think like this because of your recent posting to Rosemary about this issue.   All that being said, here goes...

You can look at the Q2-Q5 array as a black box with three ports.  There is a current in port, I_IN, a current out port, I_OUT, and then the AC current output port, AC_OUT.

We know that the black box is drawing power from the power supply via I_IN and I_OUT ports.  Current, i(t), flows through the device and there is some sort of voltage drop, v(t), across the device.  We don't necessarily know what i and v are at any specific time, but we know that (i(t) x v(t)) represents the instantaneous power consumption of the device.

We also know that the sum of the currents I_IN, I_OUT, and AC_OUT equal zero.

With respect to power, we know that the device dissipates power as a function of time, p(t).  We also know that it outputs power to the outside world via the AC_OUT port, and that is a function of time, p_ac(t).

What does this all boil down to?  The true battery current can be monitored on I_IN or I_OUT.  You don't really have to care about the AC current flowing in and out of AC_OUT.

The Q2-Q5 MOSFET array in negative oscillation mode is just a black box that dissipates battery power, that's the only thing that you have to worry about.  The black box happens to have a port that exports AC power to the outside world, but all of that power is accounted for if you simply measure the current flowing through the black box and measure the battery voltage.  Does that make sense to you?

So, in plain English, the true current being drawn by the circuit is through the function generator.  You can completely ignore the AC current going through the CSR because all of the power is accounted for by measuring the current going through the function generator and the battery voltage.

So, assuming that makes sense to you, then the next problem is measuring the true battery voltage.  The assumption is that the battery is powering the circuit with steady DC and the circuit itself is sending an AC voltage signal back to the battery.  At the very high frequency of the AC signal, the battery simply looks like a high-impedance load.  As a result you are seeing a "fake" AC waveform superimposed on the true DC battery voltage.

The issue of the battery voltage may be a lot more complicated than that, but that's my first crack at it.  You have those long battery wires also so if you have a black box injecting a 2 MHz voltage signal back to the battery, you have to start looking at things like the impedance vs. frequency for all of the devices, etc, etc.  It's somewhat of a mess.

MileHigh

[TinselKoala]

"Somewhat" is right.

So.. what happens when NO FG is used at all, nothing hooked to the circuit at its points, and one simply "tickles" the Q1 gate/Q2 source  with a suitable resistor attached to batt positive? By tickle I mean no full contact, just a scratch and then removal.

[picowatt]

MH,

I would think that only the Q2 DC bias current (likely around 200ma +/- 50ma) and less than 20% (possibly closer to or less than 10%) of the AC current would be unaccounted for during the osc phase if the FG common was connected to BAT- instead of the CSR.  The bulk of the AC current would bypass the FG via the Ciss reactance of all the MOSFET's which would be much less than Rgen at Fosc.

PW

[MileHigh]

Hi TK:

With just a tickle and no function generator I think Q1 would start to spontaneously oscillate and some current wold flow through the CSR.  Q2-Q5 would probably oscillate as a slave to Q1.  They Q2-Q5 gate input comes from the Q1 source and the Q2-Q5 source would feed back to the Q1 gate.  Note also though that the Q2-Q5 gate input is tied close to ground by the CSR which and the Q2-Q5 source is on the same node as the Q1 gate.  You note that the Q1 gate input is quasi-floating.  It's floating as long as Q2-Q5 are off.

There is a chance that nothing would happen also but I suspect that Q1 would oscillate.

MileHigh

[picowatt]

TK,

Fast tickle= partial turn on of Q1
Slow tickle= greater turn on of Q1

Q2 stays off, Q1 gets warm until leakage current turns it back off.

PW