Re: Calibration Of Electronic Equipment In The Home Workshop

On 2 Mar 2007 15:09:30 -0800, "David L. Jones" Gave us:

It doesn't matter how many "places" you "spot check" it, you are not going to get the accuracy of your comparison standard on the device you intend to set with it. What you do is take the basic INaccuracy of the device needing to be set, and add to it the basic INaccuracy of the standard to which you are setting it. You CANNOT get any closer than that. So, a 0.5% meter, and a 0.5% scope cannot be used together to make the scope that accurate. You need a *finer* standard than the accuracy level you wish to achieve.

You need to understand that as a basic fact, chucko.

The "basic fact" here is that we were talking about adjusting a 3% scope with a .03% meter. Now that the number are back where they belong, please procede to restate your case. The scope's vertical sensitivity could easily be adjusted to within 3% using said meter, now can't it? Just like Keith says......

On Sat, 3 Mar 2007 23:56:14 +0000, Clint Sharp Gave us:

Sorry, you dumbfuck, but you assuming that all TVs have this capacity proves even further how little you know about it.

On Sat, 3 Mar 2007 23:56:14 +0000, Clint Sharp Gave us:

Wrong again, dumbass. You'd like to think that your guess is correct, but it is not, dipshit.

On Sat, 3 Mar 2007 20:44:19 -0600, "Anthony Fremont" Gave us:

] Nope. READ HIS replies. He was talking about using a 3% meter.

Fuck you. Read HIS criteria, dipshit, don't impose yours. Remeber, it was ME that stated that the cal device had to be ten times more accurate than the target to be cal'd. So f*ck off.

That is NOT what the retarded bastard said, you retarded bastard.

Ahhh, who actually uses a scope to make accurate measurements?

The Real Andy wrote in news: snipped-for-privacy@4ax.com:

define "accurate measurements"....

Some scopes are merely waveform indicators,some can make "accurate measurements",within their specs. The earliest scopes didn't even have graticules or calibrated verticals or timebases,yet much was achieved with them.

"accuracy" is merely how close the measurement is to the true value. (and the values specified are actually "inaccuracy",not accuracy. [to be accurate...] Ex;+/- 1% is how INaccurate the measurement may be.)

--
Jim Yanik
jyanik
at
kua.net

"The Real Andy"

** Anyone who needs to.

Low frequency ( 1 to 30Hz), single shot, asymmetrical or pulse waves and high frequencies are all " grist for the mill " even with a CRT based scope.

Shame what happens with a DMM used on the same.

....... Phil

LMAO! If I use 0.5% accurate meter to adjust a something, then the accuracy of that adjusted device at that point in time at that adjusted value

*becomes* 0.5%. The device that was adjusted only gets it's accuracy figure of 0.5% *after* the adjustment. The 0.5% of the device does NOT get added to the 0.5% of the meter in this particular case!

Dave :)

On Sun, 04 Mar 2007 14:14:56 +1000, The Real Andy Gave us:

I guess the same idiots that claim they can calibrate one with a 3% meter.

Also, if you do NOT know how to make accurate measurements with scopes, you should be in some other industry.

On 3 Mar 2007 23:08:30 -0800, "David L. Jones" Gave us:

Absolutely incorrect!

If you do that, the MINIMUM error is 0.5%. It is ALWAYS greater than that value by that value plus the error of the device you think you set.

How can you not understand that basic fact?

Absolutely INCORRECT!

The error of a device is NOT tied to how it got set or what it got set with, dipshit, it is tied to precision of the circuits the device are based upon.

Wanna bet?

My point exactly.

More to the point, if you dont understand the concept of error then you should be in another industry.

On Sun, 04 Mar 2007 18:32:57 +1000, The Real Andy Gave us:

Good thing I never made that claim.

That is about the gist of what I have been trying to tell them.

Some dope thinking he can adjust his meter accurately with a damned drifty voltage reference chip should have his head examined, not his instruments!

I believe we were talking about scopes only being about 3% accurate in the vertical. You are the one that pulled that garbage out of the air about leaving the scope 6% off. You should try reading what people write instead of what you wish they wrote.

Are you really that incompetent? I AM THE ONE that stated that I could use .03% meter to adjust it. It was in my very first post in this thread. Now stop lying.

In message , MassiveProng writes

So your TV doesn't have a service mode and it doesn't have any pots to tweak? How, exactly, does it get adjusted in the factory or by a service tech then? Just because *you* don't have access to it doesn't mean it doesn't have a service mode where adjustments can be made via menu.

--
Clint Sharp

Furthermore, an analog scope cannot measure better than 1% (ie 0ne part in 100 of what is on the scope face). Now one can "cheat" by using a precision offset differenced with an input and that difference amplified to *display* (part of) that difference: note the "Z", the "W", and the more modern "7A13" type plugins. But *on the screen*, i defy anyone to consistently "read" better than one part in 100 (ie if 10 divisions on screen, read to better than 1 division on a consistent basis. Thus, for a scope, one might use standards good to 5 or more places, but the result will be no better than what has been called "slide rule accuracy". Do you believe all 15 digits of each and every number in a computer printout?

Further more, if one did this procedure using thousands of meters to "calibrate" thousands of other meters, the net resulting error is *NOT* the sum; it is the square root of the sum of the squares! But taking only *one* reference ("standard") and using it to "calibrate" only one device, the result is technically indeterminate but may be bounded by the sum of the (instrument) errors - and could be

*worse* (anybody hear of "cockpit errors"?).

*POLITICS*! !oops! did not mean to swear!

Shoot, he could hae a precision, very stable voltage reference, and still bollix up the works!