Here's a challenge for the scoposcopist.

The traces are :
Golden,  CVR "shunt" voltage drop, 0.25 Ohms DC resistance
Fuchsia: The "battery" voltage: Mean is given as 73.3 V, so this is a six-battery-pack trial. 
Turquoise: The Gate signal from the FG
Scarlet: The scope's computed math trace

It's too bad that the traces weren't displayed with the thought that they actually meant something. What use is a scope if all you are going to do is read the numbers it puts in boxes for you?  Why in heaven's name would anyone display that math trace at 10 KiloVV per division? Or the Gate at 50 V/div? Or the critical SHUNT trace at 5 v/div? Only because the thought was never given to the idea that someone might actually examine the data. Or was it? Or is it because those spikes are there....?.

Now... for the challenge.

Compute the duty cycle.
Compute the voltage of the Gate signal when it is HI.
Compute the level of the voltage drop across the CVR when the Gate signal is HI.
Compute the level of the current seen in the CVR when the Gate signal is HI.

Compute the instantaneous power level during the Gate HI signal -- this is what the Math trace would show if you could see it.
Compute the average power for the whole waveform using the instantaneous power during the gate HI portion and the duty cycle.

IGNORE any contribution from the oscillations for now.

(This is essentially the same calculation that GL and I went through last night, except that the values aren't given. You have to blow up the scopeshot and use your dividers or a ruler to get the values from the traces.)

Report, compare, contrast, discuss. Yes, there is a point, coming up, somewhere.

What is the average power dissipation in the entire circuit during the trial shown on the scopeshot, neglecting any contribution from the oscillations? And where in the circuit is this power dissipated?

Quote from: Rosemary Ainslie on May 15, 2012, 10:32:26 PM
Poynty

I still don't get it.  Are you describing what would be happening under ideal circumstances when the switch is 'on'?   Because otherwise I fail to see the relevance.  Please let me know.

Regards,
Rosie

Rosemary,

I know you addressed this question to .99 but let me also clarify.

There has been many different opinions about your circuit "floating" on the Internet. The only way to make
sure to get the correct circuit analysis is to do actual measurement on the circuit and compare those
measurements with some theoretical analysis. That is what I'm trying to do. I'm also engaging .99
in this because I know he is a very knowledgeable person.

One of the "myths" that have been put forth numerous times is that the function generator is adding
power to the circuit. And, yes, that is partly the truth. But at the positive part of the function generator
cycle, the added power is burnt as heat in the MOSFET and DOES NOT ADD TO THE RLOAD.

In the negative part of the function generator cycle we have current flowing OUT of the switching circuit
and this energy is BURNT OFF AS HEAT IN THE INTERNAL 50 OHM OF THE FUNCTION GENERATOR
and DOES NOT ADD ANY POWER TO RLOAD.

By doing the BIAS analysis I have found that there is NO WAY the function generator can ADD any power to RLOAD!

So all posters, including myself, got it WRONG when we assumed that the function generator could
add energy to to RLOAD. The only person that got it right was YOU, when you said (in a non technical way)
that the function generator does not add any power to the the load resistor.

This is WHY I do my circuit analysis, to find the truth about the circuit on how it works.

GL.

Groundloop:

QuoteIn the negative part of the function generator cycle we have current flowing OUT of the switching circuit
and this energy is BURNT OFF AS HEAT IN THE INTERNAL 50 OHM OF THE FUNCTION GENERATOR
and DOES NOT ADD ANY POWER TO RLOAD.

By doing the BIAS analysis I have found that there is NO WAY the function generator can ADD any power to RLOAD!

You are wrong for negative oscillation mode.  In this mode the signal amplifier inside the the function generator acts like a battery in series will all of the other batteries with additive voltage.  It's also possible that the voltage being output by the signal amplifier is 15 or 20 volts.  In that sense it's a "bigger battery" in series with the other batteries.

In this case, all of the batteries, and the amplifier inside the function generator, provide power that is dissipated as heat in RLOAD.

MileHigh

Ah.. .but GL... you are talking about ONE mode of operation, and the NERDs have typically been operating either in BOTH modes, or the OTHER Mode.

That is, they use a negative bias current exclusively or for most of the time. In the negative bias mode the bias source and the main battery are in aiding series and so both contribute to the entire power in the circuit. They never operate in the Positive bias mode for more than 50 percent of the duty cycle and usually much less than that, and the "desired" mode is to not use the positive bias at all, just stay in the negative bias, oscillation mode. And in that mode, it is apparent that the bias source or FG  CAN add to the power in the load... I think.


HEH... I see that MH is on top of this too. Great minds think alike !!

Groundloop and Poynty Point

Thanks for the explanation

Kindest as ever
Rosie