Testing the TK Tar Baby

[TinselKoala]

All the Tar Baby tests depend on really bad measurement.

YOU LIE, AINSLIE.

I have offered time and again to have TAR BABY tested side-by-side with NERD, even by remote control. My measurements are every bit as good as yours... better even, since all details of how MINE are obtained are right there in public, and I don't have any anomalous unexplained scope traces that could only indicate blown transistors in MY reportage.

Again, you lie, without support for your lies, and I can prove it.

[Rosemary Ainslie]

TK - you really are an absurd, petty little man.  Do you really think I'd buy the LeCroy if it was damaged?  At all?  Ever?  I'd have to be as mad as you claim.  If it was damaged they would have been covered by insurance.  I would NOT buy a broken machine.  EVER.

Right. Uh-huh. You damaged that instrument and that's why you had to buy it. And also... as soon as you hook it up to your circuit along with your function generator.... it is grounded just as surely as if you hadn't cut off the ground plug. And how does owning an instrument now "oblige" you to get it calibrated? That's just silly. You damaged the instrument and had to get it repaired and RE-calibrated.

Which is just more of that 'tar'. 

And... Rosemary.... the calibration I showed of my current measuring meters and my scope was COMPARING TO OHM'S LAW using a known resistance, measured with a CALIBRATED ohmmeter and voltmeters that all agree with one another and with CALIBRATED instruments. You can't get around OHM's LAW.

Your calibration exercise was a JOKE.  And it still is.  It's up there with your application of Ohms law to determine that power measurement. 

How do you think a calibration laboratory calibrates an ammeter, anyway? By waving a magic wand and sticking a little sticker on the instrument?

They don't STANDARDISE their measurements against uncalibrated instruments.  And if you're now claiming that they're calibrated - then PROVE IT.  Show us that certification.  By your own admission those instruments are alternatively 'cheapo's' or antiquated.

Rosie Pose

[TinselKoala]

Never mind, looks like you do in SA.

I've rented plenty of equip over the years and never gave a second thought to floating the ground when necessary.  Never had a problem. 

PW

That's because "you" know what you are doing.
If you did have a problem, though, you'd probably have to pay for the instrument, and then to use it after repair you'd need to get it recalibrated.

[TinselKoala]

Rosemary, I could perform my measurements with a string and a piece of modeling clay and they would STILL be better than yours, because I know how to add and subtract, and how to interpret measurements.

You on the other hand think that a 12 volt battery is fully charged as long as it reads over 12 volts on your multimeter.

And you think that a Watt is a Joule and a Joule is a Watt per Second.

Not only that, my challenge still stands: I'll put my measurements up against yours at any time. Let any third party set out a table of unknown electrical quantities, and let you and i both measure them, one shot, no outside help, starting NOW. How will you perform? How will I?

Anybody want to start a betting pool?

[TinselKoala]

By your own admission those instruments are alternatively 'cheapo's' or antiquated.

And that makes them inaccurate or imprecise just how?

You are severely logic-challenged, so I know you won't be able to follow along, but I'll try to explain anyway.

TRACEABLE calibration means just that. I can take my cheapo voltmeter to a laboratory and compare it to a real laboratory standard voltage source that is kept in calibration as a laboratory standard by sending it to a cal lab every year. And this will cost me nothing more than the fuel to get there and the time it takes to do it.

If my cheapo DMM reads to within 1 percent of the laboratory standard, only deviating from the standard in the MILLIVOLT digit.... less than one part per thousand .... I am satisfied that it is sufficiently accurate. You may not be, and if I was serious I'd make a calibration graph so that I could correct for even THAT small error.

If I then take that meter home with me, nothing magic is going to happen on the way home that will affect its accuracy or "calibration" even if it DOESN'T have a magic sticker on it that says "calibration void if removed". As long as I don't drop it in a pail of water or something.

If I then use a one percent precision resistor and that voltmeter to perform a current calibration of another meter, according to OHM'S LAW.... am I going to achieve sufficient precision and accuracy to tell the difference between COP > INFINITY and COP < 1 ?

I think so.

My Philips counter has a crystal-controlled oscillator in a constant-temperature oven that is always on as long as the instrument is plugged in, whether it is on "standby" or turned fully on. It is stable and accurate to some few parts per BILLION and displays nine significant digits. I can use this calibrated and precise frequency standard in various ways to validate and cross calibrate all my other instruments if necessary, even the simple voltmeters and ammeters. But this degree of accuracy is not needed in my lab, nor is it needed in yours.

And... by the way, Rosie Poser.... I don't have to prove anything to you. YOU have to PROVE YOUR CLAIMS, because  you are the one claiming OU. Oh... wait.... you've withdrawn your claims, sorry, I forgot for a moment, since you still seem to be defending them so ... astringently.