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Why Do Hobbyists Purchase The Most Expensive Handheld DMMs

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alligatorblues:
The world is filled with DMMs. There are two major kinds of  DMMs: chip DMMs and microprocessor DMMs. Chip DMMs are built around an IC that, with some external passives, performs the functions of a DMM. Calibration is done using trim pots connected to the DMM IC. These sell for \$3-\$150USD, and many times have display resolutions far beyond their specified accuracy. The last 4 digits are just meaningless.

Chip DMMs have grave limitations in accuracy, drift, features, durability and reliability. So, we're left with microprocessor DMMs. These perform largely dependent on firmware. They contain a precision voltage reference to compare their calibration constants to; calibration constants stored in non-volitile memory.

When the meter makes a measurement, it refers to its calibration constants, compares them to the voltage reference, and using firmware to interpolate says, "When these calibration constants were made, during my calibration, I received a signal, and it was equal to 1/2 of the voltage standard output.

"Now I'm receiving a signal that has a mathematical relationship to the calibration constants' relationship to the voltage standard. So, as I determine   the correct value for the new and unknown input signal, I will iteratively convert it to a number to display as its value.

This method linearizes the meter, so if it knows one value on the 10VDC scale, it can determine the value of other signals on that scale, because there is a predictable mathematical relationship  between the known value and every other possible value on the 10VDC scale, which is the slope; y=mx+b; if we have a line on a graph, every point on the line will fit the equation y=mx+b, where m and b are always the same numbers.

There are some discreet functions which are offloaded from the primary mcu to other ICs with more narrow but faster capabilities, such as Trms. At this point DMMs vary greatly in price. I am a professional, so I have certain needs and expectations I  insist upon.

I want to purchase a meter once. I don't expect it will ever fail. I expect top performance, durability, reliability, tech support, long life cycles, top-notch quality control, feature-packed, intelligent design,  and safe operation. That is why i insist on Fluke handheld DMMs!

There is simply nothing else that even comes close for features, reliability and durability.

Solder_Junkie:
There are two kinds of hand held multimeters, those that are safe to use and those that can blow up in your hands.

See this YouTube video to see why this retired professional user has a Fluke on the shelf. The interesting part is 5 mins into the video.

https://youtu.be/OEoazQ1zuUM?feature=shared

The USA made Fluke hand held multimeters come with a lifetime warranty too.

SJ

MikeK:

--- Quote from: Solder_Junkie on September 21, 2023, 05:53:21 am ---See this YouTube video to see why this retired professional user has a Fluke on the shelf. The interesting part is 5 mins into the video.

https://youtu.be/OEoazQ1zuUM?feature=shared

--- End quote ---

I would take no advice from that obvious amateur.  There are actual skilled professionals on the web; he's not one of them.

CaptDon: