Claimed OU circuit of Rosemary Ainslie

[Rosemary Ainslie]

Hi Poynty

I'm a bit concerned that your new LCR meter needs calibrating?  Or is it defective?  I'd complain to the supplier and check whether you've been sent some substandard stock.  I'm concerned that your measured inductance over the shunt resistor is out by the same factor as your measurment across the load resistor.  If you keep this up we'll have to discount your entire thesis and conclude that no instrument that you own can measure any component with any accuracy whatsoever.  Or is this in fact your thesis?

Golly.  I would suggest that you ask Tektronix if they've maybe got something you could use here?  LOL.

Rose.   

[Rosemary Ainslie]

Rose, are you referring to Glen's test #5 and the 1.5W (DUT) and 4.5W (CONTROL) figures used to get COP=3?

.99

Hi Poynty.  Glad to see you're still up.  Yes, is the short answer.  But there's also test 3 and sundry tests not yet posted. 

[poynt99]

Maybe you can put a good word in for me with the good folks at Tektronix, and have them send me 3 HV differential probes, and one current probe for a month or so 

.99

[Rosemary Ainslie]

Maybe you can put a good word in for me with the good folks at Tektronix, and have them send me 3 HV differential probes, and one current probe for a month or so 

.99

I wish.  I'm fast running out of slack here.  We're hoping Fuzzy's input will re-ignite the required exposure.  We were under some strain there for a bit.  So nice to see you around Poynt.  Do you think I did your features justice?  I over elaborated your 'feminine side' but that's because Fuzzy posted that earlier picture of you chewing on some live cables.  It seems to have dominated my focus and left me feeling confused about things.  Hopefully you're not.  LOL

[poynt99]

Rose,

The caricature is cool, although I'm not certain where the distinct double-chin came from 

I've offered to measure the inductance of Glen's original and new shunt resistors if he is so inclined, just send them to me. I'm not sure what he has now for measuring inductance, but if it's a meter anything like my cheaper one, it's not very accurate for such low readings.

I wish Glen luck with his new run of tests. I believe however, that without those HV differential probes and a good current probe, it's going to be a steep uphill battle to get good accurate measurements.

May I ask you Rose, why do you object to a purely thermal measurement of not only the load resistor, but the MOSFET and shunt as well?

It completely eliminates the need to make these difficult oscilloscope measurements, and will give true and accurate results.

The load resistor has already been done, and it is unnecessary to run a full thermal profile for each component. Simply measure the MOSFET temperature with a thermistor while it is operating at your optimum settings in the circuit, then remove the MOSFET and power it with a pure DC source to determine the DC power required to obtain the same TRAA.

After doing the MOSFET, it may not even be necessary to do the shunt resistor, depending on the result for the MOSFET. However to be complete, the shunt should be done as well.

And the bonus of this method is that it can all be done without a fancy oscilloscope/ probes, allowing other replicators to try it as well.

It's the simplest and most direct way of determining the power dissipation in each component, which is the goal of course.

So I'd like to know your thoughts as to why this route is not being seriously considered.

.99