Calibration Of Electronic Equipment In The Home Workshop

[JW]

[...]


True, 0.01% resistors are available, *but* they are extremely
expensive (over $100 each) and they are made when and if the
manufacturer sees fit to do so.

Not so.
RS Components have 0.01% resistors for AU$34.50 (US$26)
Farnell have 0.02% for as little as AU$20

You guys are paying *way* too much. We use Riedon .01% precision resistors
in our A/D products, and pay about 5 bucks apiece. Their site is down at
the moment, but even Digikey has .01% resistors for around the same price:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Criteria?Ref=3107&Site=US&Cat=34342147

"Your search criteria has expired"

I hate it when that happens...

Furthermore a search on "34342147" (no quotes) gets zero matches.
A search on "3107" (no quotes) gets matches that are not better than 1%.
Strangely enough, a search on "precision resistors" (no quotes_ is as
bad.
Worse, a search for "resistors" and wading thru the various types
gets *at best* Chip Resistor-Thin Film(67311 items) with 0.02% as the
best or tolerance listed.
So......
Where are those mysterious 0.01% resistors???

Put .01% into the search box and you'll get a link to the .01% resistors.
For quantity 1 they are 5-6 bucks apiece.

Or maybe this link will work if it doesn't expire, that is:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Criteria?Ref=916&Site=US&Cat=34342147

 

[carneyke]

reminds me of the local TV station techs who insisted that the video gear
of theirs I serviced and calibrated was off,and it turned out their 75 Ohm
termination was 87ohms.Other techs double-terminated monitors and
complained of low brightness,tried to tweak it in,screwed it all up.
Or they would have a "reference" generator at the end of 100's of feet of
coax and complain it was a few percent off.











this is good advice,because without a service manual and cal procedure,you
have no way of knowing what adjustments INTERACT with others.
Adjust a power supply,and gain and timing goes out the window.
Freq.response tweaks can affect more than one area of the signal.

for example,
TEK 475s have multiple vertical gain adjustments,and different adjustments
for the 2/5-10mv ranges.And the gain affects F-response.

--
Jim Yanik
jyanik
at
kua.net- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

I just got done calibrating a AM503 & A6302 current probe / amp
somebody took a screwdriver to. Without the manual and all required
gear (PG506), and cal fixtures it would never have worked properly
again. I work in a cal lab and the best part about iso9002 was
requiring the sealing stickers (cal void if seal is broken). We never
used them prior to iso certification.

 

[carneyke]

I just got done calibrating a AM503 & A6302 current probe / amp
somebody took a screwdriver to. Without the manual and all required
gear (PG506), and cal fixtures it would never have worked properly
again. I work in a cal lab and the best part about iso9002 was
requiring the sealing stickers (cal void if seal is broken). We never
used them prior to iso certification.- Hide quoted text -

- Show quoted text -

Forgot to mention : If you want to cal your own gear, mark any pots /
vari-caps and write down any software codes BEFORE changing. Do not
adjust the compensation capacitors in any Tektronix attenuators
without a PG506 and a procedure.

Jim Yanik - This note isn't for you, as you have seen the damage
too.....

 

[Clint Sharp]

For audio? absolutely. It had nothing to do with the DVD player's
clock. There are several industry standard tones provided, and the
disc replaced hardware TV test generators for years.

So varying the reference clock of a DVD player doesn't affect the pitch
of any tones played back off a disk? OK. I wondered because it does on a
CD player.

It carries DTS and THX certified content.

K, so it's a good for setting up home theatre equipment at the very
least

That is the current reference standard for MPEG, if you know who
they are.

Not personally, but I may have heard of them in passing.

That's good enough for me. I can verify the setup of my
FPD, FPD?
and I can setup my stereo <sic>with the audio diagnostic and
setup section.

Hey, chucko! He didn't give a GPS source. You don't get to change
the scene, pal!

Hey 'pal' I didn't try to change the scenario, I just speculated that a
GPS source would be better.

A subsequent poster mentioned a GPS setup.
Go back and read.

No need, I read that post, that's why I mentioned it. Turn down the
aggression a notch or two, I only asked a question and speculated that
there might be a better way.

 

[Too_Many_Tools]

Said the utter retard that needed to ask in a BASIC electronics
groups about something which he should already know if he planned to
attempt such a procedure.

Nice try, retard boy. Too bad you are wrong.... again.


That of calling you the retarded fuckhead that you are? Sure...
done.


Yep... that'd be you. Your nym is more correct than you'll ever
know. You're a jack-of-no-trades.

You're a real piece of shit... errr... work, there, bub.

My first advice was spot on. To make a proper cal, the source has
to be ten times better than the accuracy you wish to claim for the
instrument.

NONE of the circuits given in this thread are good enough. ALL of
those IC chips drift with T so much that calling them a cal source is
ludicrous. So are you if you think I don't now quality assurance, and
proper procedure.

You ain't it.

So it sounds like you are having a problem finding two brain cells
MiniPrick...try harder.

No more of your excuses....SHOW us how great you are.

Laugh...laugh...laugh....

TMT

 

[David L. Jones]

Wrong. That could easily leave the scope over 6% off.

It takes a much finer source to calibrate a device than the final
accuracy of the device being calibrated, dipshit.

Not in this case.
If he used a meter with 0.5% accuracy on DC volts then he could check
and adjust his scope's vertical scale to the same 0.5% accuracy.

And if you start crapping on about the tolerance of the resistor chain
adding up etc, then you haven't thought about this one hard enough...

Dave

 

[David L. Jones]

You guys must be behind the times.

My 6000 series Agilent is not behind the times, and it's only +/-2%
accurate on the vertical scale.
A good analog scope like say the Tek2465 is only 2% as well.

Perhaps those two are the exception huh? Care to post some links to
prove otherwise?
I could post until the cows come home scopes that are no better than a
few % accurate on the vertical scale.

Dave

 

[MassiveProng]

FPD?

Flat Panel Display.

You ain't too sharp, Sharp.

 

[MassiveProng]

Hey 'pal' I didn't try to change the scenario, I just speculated that a
GPS source would be better.

There's no doubt it would be better for RF frequency locks. Since we
use them at work, I have no doubts about their capabilities.

Audio though? Most of the respondents referred to audio spectrum
frequencies.

 

[MassiveProng]

Not in this case.
If he used a meter with 0.5% accuracy on DC volts then he could check
and adjust his scope's vertical scale to the same 0.5% accuracy.

And if you start crapping on about the tolerance of the resistor chain
adding up etc, then you haven't thought about this one hard enough...

If you set a scope up with 0.5% accurate source validator, the scope
will NOT have that accuracy level. It will ONLY have that accuracy
level at that set point, and that is even questionable.

 

[Clint Sharp]

Flat Panel Display.

You ain't too sharp, Sharp.

Ahh, so you're recommending calibrating test equipment using the same
DVD as you use to set up your boob tube. Explains a lot.

 

[David L. Jones]

If you set a scope up with 0.5% accurate source validator, the scope
will NOT have that accuracy level. It will ONLY have that accuracy
level at that set point, and that is even questionable.

Which is why you do it for each range and then spot check it to see
that there is no funny business. Perfectly valid technique for home
calibration of a scope vertical scale.

Dave

 

[Jim Yanik]

My 6000 series Agilent is not behind the times, and it's only +/-2%
accurate on the vertical scale.
A good analog scope like say the Tek2465 is only 2% as well.

Better look again;IIRC,it's 1.25% . That does not include the cursors.

It's not really significant,as you can't get that resolution on the screen.

 

[ehsjr]

[...]


True, 0.01% resistors are available, *but* they are extremely
expensive (over $100 each) and they are made when and if the
manufacturer sees fit to do so.


Not so.
RS Components have 0.01% resistors for AU$34.50 (US$26)
Farnell have 0.02% for as little as AU$20

You guys are paying *way* too much. We use Riedon .01% precision
resistors
in our A/D products, and pay about 5 bucks apiece. Their site is down at
the moment, but even Digikey has .01% resistors for around the same
price:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Criteria?Ref=3107&Site=US&Cat=34342147

"Your search criteria has expired"
Furthermore a search on "34342147" (no quotes) gets zero matches.
A search on "3107" (no quotes) gets matches that are not better than 1%.
Strangely enough, a search on "precision resistors" (no quotes_ is as
bad.
Worse, a search for "resistors" and wading thru the various types gets
*at best* Chip Resistor-Thin Film(67311 items) with 0.02% as the best or
tolerance listed.
So......
Where are those mysterious 0.01% resistors???

Try DigiKey Part # MR102-100-.01-ND

Ed

 

[ehsjr]

I have a well stocked test bench at home containing a range of analog,
digital and RF test equipment as I am sure most of you also do.

Well the question I have is how do you handle the calibration of your
equipment? What do you use for calibration standards for resistance,
voltage, current and frequency?

Links to recommended circuits, pictures and sources would be
appreciated.

Since this is a need for anyone who has test equipment, I hope to see
a good discussion on this subject.

Thanks

TMT

The real question is how much precision do you
really need in the home "lab"? How often have
you needed to use your DMM with how many
*accurate* significant digits? 100 minus some
*very* small percent of the time, 2 significant
digits is all you need. Do you _really_ care
if your 5.055 volt reading is really 5.06 or 5.04?

Oh hell yes, I want to puff out my chest like everyone
else and think I have *accurate* equipment.

But I'm curious as to what home circuits need meters
that can read voltage accurately to 3 decimal places?
2 decimal places? The question for current measurement:
in what home brew circuit design/troubleshooting do you
need accuracy below the tens of mA digit ? *Need*, not
*want*. Do you even trust your DMM on an amps setting
for those measurements, or do you measure the current
indirectly? How about ohms? Would you trust any
DMM, regardless of who calibrated it, to measure
down in the miliohm numbers?

To me, the design of the circuit being mesured has
to take care of all of that crap. If it is so
poorly designed that a 10 mV departure from nominal
(that is missed by my innaccurate meter) will keep
it from working, that suggests other problems.
Yes, the home "lab" person wants extreme accuracy
to as many decimal places as he can get. But when does
he ever really need it?

None of this is to argue against having the best
instrumentation you can afford, or references to
check it against, or paying for calibration and so
forth. But for myself, I need a dose of reality
from time to time when I start drooling over some
accuracy specs that I will never need at home. My
bet is that most of us are seduced by that same muse.

Ed

 

[Anthony Fremont]

The real question is how much precision do you
really need in the home "lab"? How often have
you needed to use your DMM with how many
*accurate* significant digits? 100 minus some
*very* small percent of the time, 2 significant
digits is all you need. Do you _really_ care
if your 5.055 volt reading is really 5.06 or 5.04?

Oh hell yes, I want to puff out my chest like everyone
else and think I have *accurate* equipment.

But I'm curious as to what home circuits need meters
that can read voltage accurately to 3 decimal places?
2 decimal places? The question for current measurement:
in what home brew circuit design/troubleshooting do you
need accuracy below the tens of mA digit ? *Need*, not

You surely didn't mean tens of _mA_, did you? I build stuff with PICs as
you know, and some of it is designed to run on batteries and needs to go for
long periods of time unattended. The current draw for a 12F683 running at
31kHz is 11uA, sleep current is 50nA. If I could only measure current to
"tens of mA", I'd never know if the PIC was setup right for low current draw
and I certainly couldn't have any idea of expected battery life. I wouldn't
even know if it was sleeping until it ate thru some batteries in a few days
instead of six or eight months. I think I have a need to measure fractions
of a uA.

*want*. Do you even trust your DMM on an amps setting
for those measurements, or do you measure the current
indirectly? How about ohms? Would you trust any
DMM, regardless of who calibrated it, to measure
down in the miliohm numbers?

To me, the design of the circuit being mesured has
to take care of all of that crap. If it is so
poorly designed that a 10 mV departure from nominal
(that is missed by my innaccurate meter) will keep
it from working, that suggests other problems.
Yes, the home "lab" person wants extreme accuracy
to as many decimal places as he can get. But when does
he ever really need it?

When he needs it he needs it, what can I say? Do I really "need" a new DSO?
Well I've managed to get by all this time without one, so maybe you think I
don't really "need" one. I see it like this though, I don't get allot of
time to tinker anymore. I'd like to spend it more productively. Instead of
fumbling around and trying to devise silly methods to make my existing
equipment do something it wasn't designed to (like going off on a tangent to
build a PIC circuit that will trigger my scope early so I can try to see
some pre-trigger history).

None of this is to argue against having the best
instrumentation you can afford, or references to
check it against, or paying for calibration and so

I don't know if I really agree with that. ;-)

 

[MassiveProng]

Ahh, so you're recommending calibrating test equipment using the same
DVD as you use to set up your boob tube. Explains a lot.

No, dipshit. I recommended an industry standard source, and I don't
"set-up" my boob tube you brainless twit, I CHECK its setup, and use
the disc to actually set-up my home audio system.

This ain't the days of the sixties where you get to tweak a bunch of
pots.

Stop being so think.

 

[Clint Sharp]

No, dipshit. I recommended an industry standard source,

To calibrate test gear. As specified in the original post.

and I don't
"set-up" my boob tube you brainless twit,

So you don't know how to access the service menu and make changes to the
setup of your boob tube. Fair enough, I thought someone as knowledgeable
as you would know how to do that but I guess I was wrong.

I CHECK its setup, and use
the disc to actually set-up my home audio system.

Good for you, please explain how the OP was going to use a DVD to
calibrate his test equipment.

This ain't the days of the sixties where you get to tweak a bunch of
pots.

No, you don't, all the adjustments are done via menu now.

Stop being so think.

I think, you just rant. Please get it right. Maybe you could use that
DVD to calibrate your anger response, maybe you could eBay it and your
home audio system to pay for some anger management?

 

[Too_Many_Tools]

Good comments Ed.

I want to thank everyone else who has offered *positive* comments
also.

Like I said, I think this is a need for anyone who has equipment at
home.

TMT

 

[MassiveProng]

Which is why you do it for each range and then spot check it to see
that there is no funny business. Perfectly valid technique for home
calibration of a scope vertical scale.

Dave

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.