The short answer : because I was not able to find a digital multi-meter (DMM) with accuracy ~ 100 ppm per year for less then 300 USD.
Based on the basic DC accuracy, I found that there are broadly three categories on the market:
- low end, mostly handheld with DC accuracy > 500 ppm.
- middle end, mostly bench top with DC accuracy between 20 ppm and 250 ppm.
- high end, which are used in calibration laboratories with DC accuracy < 10 ppm.
The price starts from few dozens USD and end up with 10000 USD price tag.
The price of several DMM with accuracy ~ 100 ppm was far away from my budget:
Siglent SDM3055 : 150 ppm basic DC accuracy for 449 USD
Rigol DM3058 : 150 ppm basic DC accuracy for 695 USD
Keithley 2110 : 120 ppm basic DC accuracy for 622USD
Keysight U3402A : 120 ppm basic DC accuracy for 759 USD
Keysight 34460A : 75 ppm basic DC accuracy for 945 USD
I made some preliminary calculations which point me that 100 ppm DC only DMM can be made for less than 300 USD. Of course if you have access to calibration grade DMM which in my case was true.
Why open DC Multimeter?
I believe that the openness, transparency and the free, unrestricted access to knowledge and information keeps the technology to move forward.
The long answer : I lost somewhere my Kyoritsu DMM 1012 and start looking for a new DMM with a good price for the accuracy. After few days spent on reading datasheets, comparing prices and reading reviews, I was not able to find good enough for the my price limit. So I started to think, why not to make one?
Based on the basic DC accuracy, I found that there are broadly three categories on the market:
- low end, mostly handheld with DC accuracy > 500 ppm.
- middle end, mostly bench top with DC accuracy between 20 ppm and 250 ppm.
- high end, which are used in calibration laboratories with DC accuracy < 10 ppm.
The price starts from few dozens USD and end up with 10000 USD price tag.
The price of several DMM with accuracy ~ 100 ppm was far away from my budget:
Siglent SDM3055 : 150 ppm basic DC accuracy for 449 USD
Rigol DM3058 : 150 ppm basic DC accuracy for 695 USD
Keithley 2110 : 120 ppm basic DC accuracy for 622USD
Keysight U3402A : 120 ppm basic DC accuracy for 759 USD
Keysight 34460A : 75 ppm basic DC accuracy for 945 USD
I made some preliminary calculations which point me that 100 ppm DC only DMM can be made for less than 300 USD. Of course if you have access to calibration grade DMM which in my case was true.
Why open DC Multimeter?
I believe that the openness, transparency and the free, unrestricted access to knowledge and information keeps the technology to move forward.
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