Edit: See further down for groupbuy on Ut210e. Comment in Freeme’s thread to join the groupbuy list
Original OP: I’ve now blown two DMM’s with too high of current, and my newest one doesn’t seem accurate at all. I’m interested in going to a clamp meter. Has anyone used any of the cheap chinese models? I’m looking around $25-35. I’m looking at the UNI-T UT204A or UT203 possibly.
I have a clamp meter which I think detects DC, but it’s buried since it’s too big for anything I might need it for.
If you’d go by the local auto parts store or junk yard, you could pick up a Ballast Resistor from an old point-style ignition system. You could wire it in series, measure V across it, then compute your I to see if your meter can handle it. That would ultimately be faster than going back to HD…
Replacing the fuses & batteries isn’t hard, but I’ve seen meters that use weird proprietary screw heads. Fortunately I have all those bits, so…
Fuses actually offer suprisingly limited protection. Even the best fast blow fuses take milliseconds to open up, you can fry electronics in microseconds. Exceed the
maximum rating on the input by an order of magnitude (factor of 10), and odds are both the meter and the fuse will be toast.
I've blown four since I've owned my DMM and nothing was harmed. That's the point of having a fuse. I just popped it out and dropped In a new one. I guess there's no knowing what kind of fuses they're using in some of the budget meters, but "Limitron KTK-10" are pretty standard fuses in DMMs. Mine is a Brymen, but I know that the Flukes have standard "Limitron" fuses too. They're pretty standard. I'm pretty sure it would be a waste of money if the fuse couldn't protect your $450.00 Fluke.
I have an Amprobe clamp on at work that I use, but way out of the range for me to buy off the shelf. I use one piece of 12 Ga multistrand copper that I cut at 5” long to maintain consistency during measurements. I will be interested to see what pops up here for budget options.
I swear I’ve read that thread 20 times over the last couple years, and I just don’t get it. Also it’s clear I need a reliable meter to tune in the new shunt, which I do not have.
I used a bench top variable power supply to make mine. I don't know how accurate the meters on it are, but it's all I have to go by. I just cut a 6" 14ga wire with an inch of insulation stripped from each end. I then put the wire in the power supply and then ran 10amps of current through the wire. I then probed for the spots that gave me 10mV. I then soldered wires to spots just a tad wider than those spots because the solder reduces resistance a tad. You can then tune the wire be either notching the wire or adding solder. You have to let the wire cool from soldering before testing it for accuracy.
My version, banana sockets are to plug a multi-meter (set to mV range):
22 AWG wire for shunt, about 8” gives 10 mohm (so 10 mV/A). Trim exact length by using an amp meter in series with the shunt and a voltage source. Going over 10A you should probably use thicker wire and lower resistance for the shunt, as per the linked thread above.
Note that copper wire has a relatively high tempco re. resistance. There will be a 4% change in shunt resistance with every 10 C change in temperature. Proper shunt/resistance wire is manufactured from alloys with much lower tempcos.
These are made with Nichrome wire where the resistance increases as the wire heats so I wouldn’t go there. They will handle a lot of current though, just not accurately until the temperature settles down. These were used to compensate for lower battery voltage while the starter motor operated, then lowered current afterward to make the coil and contact points last longer.
was undecided between that 210E (24-28 USD) (because of the 1mA resolution, I prefer precision for what i do than 500+ Amp capability), the Mastech MS21080-35 USD (the cheaper 2108A version has not TrueRMS and no Inrush current 27-30 USD) but in the end I opted for a 216C for no reason…. (as always), well the reason was mainly because it seemed a bigger discount even if i ended spending more of what i had planned…47 euros shipped tskk . Always speaking of DC current clamps
It was able to detect 8mA (the clamped displayed 0.01A) And testing various low currents with my linear variable PSU i got very very decent results
But somehow i was not able to measure the battery drain of my sister Toyota Yaris with headlights on, I whink they should absorbe near 9Amp, dunno why
Instead , don’t know if it was reliable for instantaneous DC current (because it calculates the inrush current doing the Fourier transfor of a variable current) i was able to measure 466 Amp from the same yaris D4D to start the engine (battery rated for 570Amp cold start, so it could well be)
If you need me to check something just ask, i’ll do what i can while i’m not at work