What do you mean by 3 1/2, 3 3/4 digits specs for a DMM

[Sukhbinder]

Some one asked me about the 3 1/2 , 3 3/4 specs for a DMM, i explained it as i found it in a book but i'm myself not completely satisfied with the explanation.

Do any of you guys have a good explanation for the above. I do understand the digits specs like 1999, 3999, 5999, 79999 (as i have them on my DMMs)

Thanks in advance

 

[audioguru2]

The first digit on some digital multimeters is simply a 1 or a 0. It is called "half a digit" so if it reads 1.555 then it has three and a half digits.

Some digital multimeters can show 7.555 then maybe they have three and 3/4 digits.

 

[Sukhbinder]

Thanks for the help audioguru.

I found the explanation for the 3 1/2 system and i've observed that it applies to all DMM with 1999 counts, it says that the first digit is a 0 or 1 because if we have a range of 0.999 then next range will be 9.999 and to measure 1.042, 0.999 is not adequate and in the 9.999 range the resolution is too bad and 1.042 cna be approximated as 1.03 or 1.05 but by using a half digit (0 or 1) the range is 1.999 and the next range is 19.99 so 1.042 can be satisfactorily measured in 1.999.

however i can't seem to make out the logic behind the 3 3/4 digits as i have 3 DMMs all with 3 3/4 digits but counts 3260, 3999 and 5999.

Still looking for the 3 3/4 logic.

got one DMM with 79999 counts but no mention of 4 1/2 or 4 3/4 ???

thanks alot anyway