Testing the TK Tar Baby

[TinselKoala]

I can see +1.25V across the CSR during the HI phase (5A) but  overall average current depends on what is happening during the LO oscillating phase as well. Is there an expanded scrn shot available?

The scope has enough cycles to get a rough idea of the mean voltage across the CSR. The only trouble is the CSR inductance can and will throw off the reading a bit, as I showed in my document, but not that much.

Consider that the 179mA could be a realistic value. I would need to see a zoom-in of the oscillation to know if the 179mA is accurate or not. Again, I am talking average current, you have been referring to the current during the HI time.

My main point in this has to do with the amount of power that the circuit must handle, for how long it must handle it, and where that power must be dissipated.  During the HI time, there is 5 amperes of current flowing in a mosfet that has 2 ohms RDss and that is sitting on a bit of heatsink about the size of a matchbox. And this HIGH time is nearly half the total time.
During the LO time, do the oscillations actively cool the Q1 mosfet, you know, the one that they aren't happening in?  I don't think so. So the Q1 mosfet itself is dissipating an average power of nearly 25 Watts (5 x 5 x 2 x .45) for the duration of the experiment. Isn't it? Have you ever grabbed onto a 25 watt light bulb that was on for a while?

[MileHigh]

Rosemary:

So you don't have any self-respect.  If you perceive that a discussion is threatening to your proposition, even if it were to be a discussion between two PhD electrical engineers, you would trash what they were saying with whatever low-life ghetto gutter garbage that you choose to spew out of your mouth.

The truth doesn't matter to you, all that you know is that you have to denigrate and dismiss anything that you think is a threat, even if it is the most reasonable intelligent discussion between people that are so far superior to you in the subject matter, so far superior that it's like comparing an amoeba to an elephant.

The low-life grotesque pandering of Rosemary in a desperate search for words, any words to attack the people and the ideas that she feels threaten her her little pulsating resistor - how low can you really go?

How can you look at yourself in the mirror?

MileHigh

[poynt99]

@.99:

0.179 x 73 = 13.07 x 4 = 52.3 Watts average according to the numbers in boxes, for the full 100 percent period.

(1.25 x 73) x 0.45 = 41.1 x 4 = 164.25 Watts POSITIVE during the Hi time. or .45 of the period. This comes right off the scope traces. I put a blowup graphic up. Are my figures wrong?

So to bring this figure DOWN to the 52.3 watts average you cite, what then would be the current and power required in the oscillations?

I would need to see an expanded view of the oscillation portion. If that "CYCLE MEAN" happened to take a mean during the oscillation, there is a lot of power there in the opposite direction, and that could easily knock your 130W down to 50W average power.

And how do you account for the difference between the "cycle mean" and the "mean"? Cursors, foiled again?

TA: I see you've already addressed that. Do you know that the LeCroy also doesn't know to take the mean across a full number of cycles? It displays the mean of what's on the screen.

Yes, I am aware of that issue. I did say it uses the full width of the display. The more cycles, the better, but in my experience taking a lot of MEAN measurements, 10 cycles is pretty good, even if they aren't lined up perfectly to fit exactly 10. So here with 6.5 cycles, it won't be the best, but it will certainly be in the ball park.

[TinselKoala]

nd NOTA BENE - TK's UTTERLY incorrect reference of the switching period.  THAT in itself is GROSS MISREPRESENTATION.

Whaat?

The timebase is set to 20 microseconds per division (top left).

There are 5 minor divisions per major division, so each minor division is 4 microseconds.

On the duty cycle I deliberately did NOT include the "ramp up" time in the ON time. I will, gladly, if you like. That will make the ON time power even greater, because while it lowers the current figure slightly, it adds to the time during which it acts.

So not including the ramp up to the steady state, I see 14 microseconds of ON time per period, and a total period of 31 microseconds.

Is this a gross misrepresentation? How?

[Rosemary Ainslie]

Rosemary:

So you don't have any self-respect.  If you perceive that a discussion is threatening to your proposition, even if it were to be a discussion between two PhD electrical engineers, you would trash what they are saying with whatever low-life ghetto gutter garbage that you choose to spew out of your mouth.

The truth doesn't matter to you, all that you know is that you have to denigrate and dismiss anything that you think is a threat, even if it is the most reasonable intelligent discussion between people that are so far superior to you in the subject matter, so far superior that it's like comparing an amoeba to an elephant.

The low-life grotesque pandering of Rosemary in a desperate search for words, any words to attack the people and the ideas that she feels threaten her her little pulsating resistor - how low can you really go?

How can you look at yourself in the mirror?

MileHigh

MORE SLANDER AND MORE ABUSE. Guys the question is this.  WHY IS HARTI ALLOWING IT? 

Regards,
Rosemary