Resistance is not as futile as you might think....
Continuing with multimeter evaluation, I measured from 0.100 Ω through 200 MΩ.
You'll notice a lot of spaghetti below 50 Ω, which demonstrates how inept a typical multimeter will be at measuring low resistances. Anything below 10 Ω should be acquired with a milli-ohmmeter if you need significant accuracy.
Many of these charts will have a big wiggle at low resistance. This is due to low number of significant figures or inability to accurately capture a resistance value. Note: At every opportunity I used the REL feature to automatically account for lead resistance, or I manually subtracted it when a REL button wasn't available.
What the data doesn't show is the meter's ability to get to a good stable result quickly. I found this varied widely across devices. For the purpose of this review, I'm only focusing on the measured result, acquired with patience.
The orange curve below is a meter which was converted into a 4-wire tester by adding a 100 mA current source inside the device, which can be turned on or off as needed. As you can see, the special circuit gives this meter a spectacular ability to measure low resistances:
Little transistor testers are good at identifying a wide range of components, but they fail to be accurate. It's interesting how these two devices purchased at different times behave quite consistently. (The modifications to the first one is a different lithium cell, a foot pedal optional input, and an on/off switch)
The REL feature of the AN870's is effective. Excellent overall:
The ZOYI did better at the lowest resistances, despite lacking the REL feature that the FNIRSI features. These were measured using latest firmwares. I was able to obtain Rs measures at 20 Megohm, however they are not rated for that particular value (for good reason):
Glad to have the ZT-5566 on my bench. Very impressive.
The FNIRSI HRM-10 is a battery internal resistance meter, using 1kHz for measuring instead of DC. I use it as a milliohmmeter all the time.
The East Tester uses a 4-wire setup for measuring components. Unfortunately, the method doesn't translate into particularly exciting results.
The grand finale is the devices which I can count on for the best readings possible.
Below 10 ohms, I'll grab the first ZT-MD1 tweezers. Above 10 ohms, the AN870 with the red boot is the best.
NOTE: This graph is zoomed in by 6 times compared to the graphs so far.
Regardless whatever multimeter you find works the best, it's still best to have something with 4-wire connections to function as a milliohmmeter below 10 ohms.
It just so happens the ZT-MD1 has these 4 connections terminating at the two tip. This leads to convenient and accurate results comparable to a milliohmmeter.
Hopefully you have a multimeter with a resistance mode similar to the accuracy of one of these meters. If not, check out the list! Many were reviewed on Darren Walker's channel. Keep On Testing!
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