I saw this question posted to ELECTRONICS HOBBY CIRCUITS IN FACEBOOK group:
“can you tell me what is the meaning of calibration date of a multimeter and does it effect the work of a multimeter if it expires the calibration date?”
The answer to this is:
As all circuits will drift with time, the DMM will need to be periodically re-calibrated to ensure that it is operating within its specification. The calibration period will form part of the specification for the DMM.
The calibration includes verification that meter works within specifications and if needed tuning the meter.
If a multimeter expires the calibration date, it might or might not measure at the promised accuracy anymore. Meter will still work nicely, but there is possibility that the measurement results would be slightly off from promised accuracy.
Here a video that describes basics of calibration
Here is an instructional video on calibrating multimeters:
How to Calibrate Inexpensive Multimeters
I have done calibration to my multimeters. In most cases I have used an accurate calibration signal source to make sure that the that mu meters are still in calibration. I have tried to avoid touching the calibration settings inside multi-meters, unless the following needs are met: there has been a significant error, I have has access to a good calibrated signal source or meter I can compare the device being calibrated against and calibration instructions available for the multimeter I have (I have the instructions for some meters I have).
In March 2020 I participated to a multimeter calibration event at the local HAM club. They had a very nice very accurate Fluke calibration tool for people to use at the event (owned by another HAM club) that could generate very accurate test signals to check all the different multimeter measurement ranges (DC voltage and current, AC current and voltage at different frequencies, resistance, etc..). Both of my UT-81B and my working Mastech MS8209 were proven to measure as accurately as their documentation promised.
“Can this calibration done two or more than tho times in a single DMM?”
Calibration can be made many times for a multimeter. Typically calibration is done in applications where guaranteed accuracy is needed once per year. You can make calibration check how accurate it is as often and as many times as wanted. Iy does not wear out meter more than normal measuring.
If adjustment is needed, meter needs to be opened and trimmers adjusted, which causes some wear to multimeter.
17 Comments
Tomi Engdahl says:
Repair: Fluke 5700A Multifunction Calibrator
https://www.youtube.com/watch?v=qhr6h7wuqo0
Tomi Engdahl says:
DIY DMM (Multimeter) Voltage Calibration (Centech P37773/Mastech M9508) PART ONE
https://www.youtube.com/watch?v=Kr_8yg3ookw
WARNING: Experts will tell you this is a waste of time, as low quality DMM units (such as the one presented in this video) are not accurate enough to even bother calibrating and not accurate enough to use to calibrate other meters. They are probably right. There is definitely an over-the-top approach that is the textbook correct way to do anything, and then there is the irresponsible and maybe even negligent approach to do anything. This falls somewhere in the middle.
In this video, I show you how I “calibrated” the voltage input reading on my Harbor Freight CenTech P37772 (aka Mastech M9508). I put calibrated in quotes because 37 out of 39 experts will agree that this is an exercise in futility as a $15 digital multimeter can’t really be calibrated. Full disclosure, here is the documented accuracy specs for this multimeter:
Range —– Resolution —– Accuracy
200mV —– 0.1mV —– ± 0.5% of rdg ± 1 digit
2V —– 1mV —– ± 0.5% of rdg ± 1 digit ← What I was using.
20V —– 10mV —– ± 0.5% of rdg ± 1 digit
200V —– 100mV —– ± 0.5% of rdg ± 1 digit
1000V —– 1V —– ± 0.5% of rdg ± 2 digits
Now that that’s out of the way, let’s get to it!
DIY DMM (Multimeter) Voltage Calibration (Centech P37773/Mastech M9508) PART TWO
https://www.youtube.com/watch?v=j7tfZEhU_NU&t=173s
This is PART TWO of the Do-it-Yourself Multimeter Calibration series. Part One explains the methodology and how to use a reference (Duracell AA Battery) to check the calibration of your DMM, and then I show you how to adjust the calibration on the Centech P37773 (Mastech M9508) meter.
Tomi Engdahl says:
Fluke 77 teardown, calibration and servicing (#008)
https://www.youtube.com/watch?v=9ptPe_AeZiQ
Tomi Engdahl says:
VoltageStandard Vref5-002 – 0.002% Precision 5V Voltage Reference
https://www.youtube.com/watch?v=0XAMNsRtZPU
The Vref5-002 is a 5.000V, 0.0025% accurate precision voltage reference. Housed in an anodized aluminum enclosure with rubber feet, this reference will be a great addition to your test bench. Based upon the Cirrus Logic VRE305A (used to be Thaler), proprietary laser trimmed circuitry provides excellent stability and accuracy without an oven! Output terminals are gold plated banana jacks. Input power is provided by included 24VDC, UL listed power supply. Input power connector has locking ring to prevent accidental unplugging. Red LED adjacent to output terminals provides visual indication that reference is powered-up. At time of shipment, the Vref5-002 is adjusted to be within 5uV of 5.000000V as measured by our calibrated 0.0008% accurate HP 3458A 8.5 digit DMM. Free calibration is included for first two years after purchase- user just pays shipping/insurance both ways; subsequent calibrations are $7.50 plus $8.50 shipping.
Tomi Engdahl says:
#1131 LT1019 Voltage Reference 0.05% Absolute
https://www.youtube.com/watch?v=nNbY0gMCsUo
Tomi Engdahl says:
Multimeter Voltage Accuracy – AD584 Voltage Reference – 12v Solar Shed
https://www.youtube.com/watch?v=BQIe2hfq9-M
I use my multimeters a lot. I use them to determine whether a device over charges my lithium ion cells and my Arduino projects are reading accurately for example. But how do I know that my meters are correct? And it begs the question whether all meters can be relied upon in this day and age.
In this video I test my meters against an AD584 precision voltage reference module which I bought from Ebay: https://goo.gl/30alpf
Tomi Engdahl says:
#057 AD584KH (AD584-M) High Precision Voltage Reference Module 2.5000 / 5.0000 / 7.5000 / 10.0000 V
https://www.youtube.com/watch?v=K5a-O8B6fj4
Tomi Engdahl says:
Scullcom Hobby Electronics #8 – Precision Voltage Reference Modules
https://www.youtube.com/watch?v=zm_ZBT4t4dA
Review and teardown of 3 types of Precision Voltage Reference Modules which are useful for checking the calibration of Digital Multimeters.
Tomi Engdahl says:
Voltage Standard Ref Tests – Digital Multimeter reference / accuracy check
https://www.youtube.com/watch?v=jXvGpFMKj5U
Tomi Engdahl says:
Measuring 2.5V from two voltage references
https://www.youtube.com/watch?v=LW17hxGkVQ0
A viewer requested that I use my multimeters to measure voltage less than 5V. Here’s a measurement of 2.5V from two voltage references
Tomi Engdahl says:
Calibrate your multimeters, voltmeters, ammeters and ohmmeters
https://www.youtube.com/watch?v=3ON-5hnv2_k
In this video we’ll talk about a simple and cheap way of calibrating our measurement devices – whether multimeters, voltmeters, ammeters or ohmmeters. Of course, we’re talking about those cheap or medium priced ones, not those expensive, high quality ones, that tipically come already calibrated (such as Fluke, Agilent, etc.).
Where i live, the cost of producing this device was around 25 $ / 20 euro.
Electronic schematic for voltage reference – 6:38
How to create our fixed precise resistors – 24:35
Ammeter calibration procedure – 40:43
Calibrating my own multimeters – 43:44
Final thoughts – 45:10
Project files can be downloaded from here:
https://www.youtube.com/redirect?event=video_description&redir_token=QUFFLUhqbHFVcUNVZm5ZbWZjekdGdXAtR0tTSDNWT0thZ3xBQ3Jtc0trc3V6WE85dG54alJ1empKcE5BYjhEQXhmc25PVmRXZ01US3IzS1hmSC1ZZEhibFBCS3lxTEwzaGJzM3phakE0X3BNMWZPQnl0Y3pkbjIzZVBya3ZnZnZ5OTB5NTEzMEp6eXBQV045Qm4tZ3R0a3J5WQ&q=https%3A%2F%2Flectiivideo.ro%2Fmateriale%2Felectronica_aparat_calibrare.zip&v=3ON-5hnv2_k
Tomi Engdahl says:
Fluke 732A DC Voltage Standard & low cost DIY attempt
https://www.youtube.com/watch?v=N1F4duEZR_s
Tomi Engdahl says:
Calibrate your multimeters, voltmeters, ammeters and ohmmeters
https://www.youtube.com/watch?v=3ON-5hnv2_k
In this video we’ll talk about a simple and cheap way of calibrating our measurement devices – whether multimeters, voltmeters, ammeters or ohmmeters. Of course, we’re talking about those cheap or medium priced ones, not those expensive, high quality ones, that tipically come already calibrated (such as Fluke, Agilent, etc.).
Tomi Engdahl says:
How to Calibrate Inexpensive Multimeters
https://www.youtube.com/watch?v=-izNaaLWG1k
Here is how to calibrate low-cost multimeters. This is very simple and only takes about 10 minutes with the right equipment.
Tomi Engdahl says:
AD584 4 Channel 2.5V/7.5V/5V/10V High Precision Voltage Reference Module With Transparent Housing
https://www.aliexpress.com/item/1005005223914932.html?src=criteo&albch=criteo_New&acnt=criteo-LF&albcp=157651&device=pc&clickid=65006040213bf24c460578b7dd440c19_1694523456_1005005223914932&aff_fcid=53fcff2595fb4e83a13a25f742a6086a-1694523871613-03756-UneMJZVf&aff_fsk=UneMJZVf&aff_platform=aaf&sk=UneMJZVf&aff_trace_key=53fcff2595fb4e83a13a25f742a6086a-1694523871613-03756-UneMJZVf&terminal_id=a84dd682a66047c694dfe5628f2eb974&afSmartRedirect=y#nav-specification
AD584 voltage reference 2.5V/5V/7.5V/10V high-precision reference voltage source voltmeter correction
https://www.aliexpress.com/item/1005005801788613.html?spm=a2g0o.detail.1000014.19.62a1d5btd5bt9D&gps-id=pcDetailBottomMoreOtherSeller&scm=1007.40000.326746.0&scm_id=1007.40000.326746.0&scm-url=1007.40000.326746.0&pvid=016d290d-e0de-4140-9ef0-a805965b8d09&_t=gps-id:pcDetailBottomMoreOtherSeller,scm-url:1007.40000.326746.0,pvid:016d290d-e0de-4140-9ef0-a805965b8d09,tpp_buckets:668%232846%238111%23456&pdp_npi=4%40dis%21EUR%2115.27%2114.51%21%21%21116.93%21%21%402101c5b116945239607832542e56be%2112000034400691397%21rec%21FI%212528467667%21S
Tomi Engdahl says:
DIY voltage & current reference standard
https://avdweb.nl/tech-tips/electronics/multimeter-calibration-diy
Tomi Engdahl says:
https://hackaday.com/2024/05/09/ask-hackaday-do-you-calibrate-your-instruments/