[pic heavy !] Mineral oil stabelized voltage reference

[mazurov]

If you have a good ohmmeter, just set up an experiment. Measure the resistance, write it down, solder, measure again, compare. Then repeat with another resistor, this time holding it with needle nose pliers between the body and the solder joint. Compare the difference in resistance induced by first and second technique.

[Spikee]

If you have a good ohmmeter, just set up an experiment. Measure the resistance, write it down, solder, measure again, compare. Then repeat with another resistor, this time holding it with needle nose pliers between the body and the solder joint. Compare the difference in resistance induced by first and second technique.

Ill have to try that when im back home. That qill take about 30 mins.

[Conrad Hoffman]

That will work if you have a 6 1/2 digit meter and the resistance value is in a "good" location on one of the scales. Better is to make up a 4-resistor equal value bridge and look at the null.

[Spikee]

i will do the resistor matching using a wheatstone bridge but that is for a later date...
I just checked my Agilent U8001A psu (in calibration) versus my rigol DM3058 and my newly acquired Fluke 87 III .

The maximum set resolution of the psu is 2 after the decimal point but that will be good enough indication till my dmm check arrives.

Agilent U8001A set voltage: 01.99V
Fluke 87 III:    1.9883V (lsb from 2-> 4)   
Rigol Dm3058: 1.98894V (average 2 minutes) (have to hook up to the pc to see the full 6 1/2 digits)
The test leads are both equal length so i can assume the Fluke is the one that has drifted a little.

I am testing the non soldered resistor vs soldered resistor and soldered with heatsink and without now.
       

[ftransform]

Are you gonna go after some kind of oil immersion? I know most people here say it is a bad idea but I think it would be cool because no one has ever done it at home that I know of.

AS ghetto but good quality moisture sealing why not put your tupperware (with oil and resistors and whatnot) into a big mylar bag with a desiccant packet? Even heat seal it maybe.

[Jay_Diddy_B]

Hi Group,

Remember if you are needing the ultimate in precision, you can not use any old cable to hook up the instruments, you should use low thermal EMF cables like these:

http://www.pomonaelectronics.com/pdf/d5291A_102.pdf

If you have a sensitive meter, you can see them drift if you warm the input terminals with your hand.

Check these application notes from Linear Technology:

http://cds.linear.com/docs/Application%20Note/an09f.pdf


This other application note talks about how to get high accuracy using DACs and ADCs. By using a DAC you remove the need to match all the resistors, the manufacturer has already done that for you.

http://cds.linear.com/docs/Application%20Note/an86f.pdf



Jay_Diddy_B

[Spikee]

Measurement results:
https://dl.dropbox.com/u/100819959/resistor%20solder%20drift%20test.pdf

Interesting findings, If you use pliers as a heatsink the resistor wont show a drift (at 5 1/2 digits measurement)
I could try hooking it up to the pc and read the 6 1/2 digits but i don't find that necessary.

@ftransform
I canceled the plans to do the mineral oil method because it would not deliver the results i want to achieve. It would try it if i had any mineral oil laying around ...

@Jay_Diddy_B
My test leads are exactly like those ones except they are not gold plated. Ratings : Cat III 1000V / 16A
The application note 86 has some good inf about kelvin varley dividers
And my favorite programming language is solder.

It is time to sleep now =/

[ftransform]

any progress?

[Spikee]

Still waiting for the switches . . . They probably are at customs :€

[cellularmitosis]

Any progress on this?  I've been very interested in building a kelvin varley divider myself recently.  Has anyone else on the forum built one?

By the way, Conrad, thanks so much for your home metrology lab articles!  Inspiration!