another small breakthrough on our NERD technology.

[Rosemary Ainslie]

Rosemary,

Again, referring to the portion of the cycle when the FG output is a negative voltage, Q1 is turned off.

At the same time, Q2 is biased on and allows about 200 ma. of DC current to flow.

PW

You argued that this returned to the battery via RLoad.  I'm asking you again.  How?

Regards,
Rosemary

[picowatt]

Rosemary,

As I said, I am not familiar with your LeCroy.  It is, however, my understanding that the "ofs" numbers, that is, the indicated offset, basically describes how far the zero volts line is above or below the center of the screen.

Again, referring to FIG3 in paper 1, the channel one trace zero volts line at the left of the screen is about 2.25 full divisions above the center of the screen.  That channel is set to 2 volts per division.  2.25 divisions times 2V per division is 4.5 volts.  The offset reading for channel one says 4.56V, which is in good agreement with my "optical" read of the zero volt line position.

The channel 2 zero volt line to the left is about 1.75 divisions below the screen center.  That channel is set to 100 volts per division.  1.75 times 100 equals 175.  As the zero volt indicator to the left for channel 2 is below the screen center, it will be a negative number.  The indicated offset for channel 2 is -176V, again in good agreement with my optical read.

The channel 3 zero volts indicator is about 2.3 divisions below the center line.  Channel 3 is set to 10volts per division, 2.3 times 10V equals 23.  As the zero volt line is below the center of the screen, it will also be a negative value.  The indicated offset is -23V, again in good agreement with my read.

I believe I am reading the scope correctly.

As my eyes grow old, I truly dislike having to read divisions off a scope, and the LeCroy's are hard to see.  I use my cursors all the time!

PW

[TinselKoala]

(snip)
With this knowledge I can now articulate the proper "LEDs of Doom" configuration for you in negative oscillation mode:

1.  A pair of back-to-back LEDs in series with the CSR.  Both will light up because of the AC signal from the AC output from the AC-coupled Q2-Q5 MOSFET oscillator.

2.  A pair of back-to-back LEDs in series with the function generator output.  Only one LED will light up indicating that current is flowing clockwise through the circuit and the battery set is discharging.

The days for your proposition are numbered.

MileHigh

Um... I thought we already found out what happens when a LED is put into TarBaby's main current path. And now... we've found out again. You owe me another two green LEDs. But I can't get oscillations with the LEDs in series at the normal gate drive setting. Increasing gate drive results in ONE LED lighting, the one that is correctly biased but no oscillations. Increasing the negative amplitude further results in letting the white smoke out... or as just now, a POP and a spalled off bit of exploded LED.

Now... in PARALLEL with the CVR... that's another story and we already  know the outcome from that, too, I think.

When we start blowing up components, I know we are making progress.

I just can't figure out in which direction.

[picowatt]

Rosemary,

During the period of the FG output when its output is a negative voltage, Q1 is turned off and Q2 is biased on.

The bias current is approximated to be 200ma.

If the FG lead's ground clip is attached to the BAT-, then:

The Q2 bias current flows from the battery, thru Rload, thru Q2, thru the FG, and back to the battery.

If the FG lead's ground clip is attached to the end of the CSR opposite the BAT-, then:

The Q2 bias current flows from the battery, thru Rload, thru Q2, thru the FG, thru the CSR, and back to the battery.

PW

[TinselKoala]

@PW: As you  may know, I use another LeCroy toy WaveSomething, a 104x IIRC, at the other non-disclosed location where I sometimes operate. It's the scope I showed in the JT/measurement pitfall demo that Rosemary thinks I faked somehow. I also use an older "real" LeCroy DSO that doesn't run as an application on top of Windows, a powerhouse 9370M.

I assure you that you are correct in your interpretation of the "offset" indication in the channel settings boxes and wrt the "eyeball" determinations using the LeCroy zero-indicator little lines under the channel numbers at the left of the screen. You've got it right and Rosemary's "explanation" is, as usual, so much word salad. The channel trace offset is used in some of the scope's internal math but I don't think any of that is invoked in this case.