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Lab Playground based on Agilent 34401A / RS232 / Arduino / USB / PC

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quantumvolt:
Hi.

Anyone interested in DIY accessories for their DMM? I see that most treads here are hunting for the elusive 10.000000 Volt - something that I as physicist find somewhat naive ...

No, I want to make peripherals of all kind. One example could be automated matching of resistors. The DMM can easily be externally triggered, and will promptly report the measurement in signal form. So you buy 100 pcs 1% Metal film resistors on a row or tape them on a cardboard strip or whatever and number them 01 to 99. You hook up the DMM to Arduino (or any microprocessor that you can program) and a display, and the Arduino tells you put the measurement leads on resistor 00, 01, 02 etc. The measurement values are stored in your PC. This process is done with your hands completely free. All you have to do is to shift the pair of leads from left to right when Arduino tells you to.

Then Arduino tells you to heat up the room (or a closed box with holes for your arms and a see through lid) a few degrees (we also need a temperature probe / thermometer), and you repeat the measurement process by moving the two probes from R00 to R99.

When this is over, it is easy to make a  C-program to find 1. The best pair (in the case of infinite resolution there are 100! = 9.33262154e157 possibilities ... might take some time  :-DMM), 2. The best 4 pairs (or whatever), 3. The best 3 resistors to use in a temperature compensated bridge , 4. How many pairs are available within 0.05% and so on. And the program tells you to pick R35 and R89, R19 and R07, etc. (no more resistor haystack on your desk).

This kind of kitchen science approach can involve a voltage source, current source, waveform generator, bridges, dividers, loops, probes, amplifiers, filters, sensors, capacitance / inductance module, milliOhm module (add a Arduino-controlled relay to the current leads and let Arduino double the measurements without lifting the probes by reversing the resistor current and averaging the values), and so on ...

Anyway - just wanted to say HI and ask for membership in the club. And also - since I have no access to a Calibration Lab where I live: Does anyone know a lab / person in the US that will accept a battery powered DIY 10 V Ref and a few Vishay 0.005% resistors (sent by mail) for measurement and return them by post to Thailand where I live. Thanks.

Harvs:

--- Quote from: quantumvolt on May 18, 2013, 04:41:40 am --- Does anyone know a lab / person in the US that will accept a battery powered DIY 10 V Ref and a few Vishay 0.005% resistors (sent by mail) for measurement and return them by post to Thailand where I live. Thanks.

--- End quote ---

Would one of these suffice?  It'll be cheaper than most other options.

http://www.voltagestandard.com/DMMCheck.html

quantumvolt:
Thanks. I'll look into it. If I buy a board from them (or GellerLab),  may be they will calibrate my other refs for a fee when I send their board in for recalib  :-/O Good idea. Thanks

Rick Law:

--- Quote from: quantumvolt on May 18, 2013, 04:41:40 am ---Hi.

Anyone interested in DIY accessories for their DMM? I see that most treads here are hunting for the elusive 10.000000 Volt - something that I as physicist find somewhat naive ...

No, I want to make peripherals of all kind. One example could be automated matching of resistors.

...


--- End quote ---

Fellow physics guy here.  Why the trouble of using arduino?

Use a logging DMM and import the values.  A program can read the import file and filter out the resistor switching  by look for the stable values (+-1% ish) between open test lead readings as resistors change occur.

As to 8 digit DMMs, well, like car guys looking for more horse power, if it pleases them, why not.  On the other hand, if they are looking for 38 digits, now that would be kind of funny.

quantumvolt:
Hi.

I know that all I need is a cable picking up regularly coming data. There are also tons of lab view and math software.

The Arduino is ment to be first step in USB facilitating the old 34401 (the newer 34410 has USB). Remote commanding the DMM and labeling the results also gives you the possibility to remove ALL effect of wires for lowOHM measurements. Using a 4-wire probe is not enough. Imo the current leads must also be reversed while the sense leads stays put. The two resulting measurements remove possible electric potential effects in the clip / resistor lead connection.

When this toddler's project is running I will be able to judge how much 2-way talk the DMM can do with a laptop through Arduino and added stuff. If feasible I can end up with a modern protocol remote controllable and programmable 20 years old instrument  >:D.

And I have stopped drinking beer (too old and fat now) and my wife has left me - so I need something to do :bullshit:. That's why I came here, and that is where the Arduino will start help me making a kinder garden wireless online ATE  :-DD

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