I put this meter in a grid dipper.

ordered 2 thinking quality would be an issue, and was correct.one was ok the other would stick all through the range 10 to 30 μA.rather than send it back, took it apart some, guessed the armature winding was rubbing on the magnet.carefully pried the top side armature away from the magnet and magic, it was then ok.

While ordering this panel meter, I was surprised at the lack of useful information, as one might fiind on a data sheet. For example, I didn't see a spec for the DC resistance inherent in this meter. I have browsed online shops like Mouser and Digikey, however. Based on their product listings a typical resistance for a DC ammeter with this range (50μA) of this type (direct action galvanometer) is often 1.8 kΩ, but there are specific models that are 5kΩ, instead.The meter I received was cosmetically a little different than pictures in this listing, differing in unimportant ways in the panel markings. The most pertinent change is that mine is marked "TOMZN®" and in Chinese characters, it is marked "Tong Zheng Electric." On the back, a sticker refers to an invalid website: www.tomzn.com.cnI thought they probably meant www.tomzn.co.cn and I think that used to be correct. However, that domain has expired.There are otherwise lots of Tomzn Electric companies in China, but they all seem to be spin-offs and mergers of the "original," and none of them advertise panel meters in their current catalog, that I could find.I think this meter might have been remnant inventory.I set out to measure its characteristics and using two DMMs and one LVR meter, the consensus value for DC resistance is 5170 Ohms. At 1kHz (N.B. this is a DC meter, but I had to measure inductance with an AC measuring instrument), the series inductance was 137 mH, and the series capacitance 80 nanoF. A.k.a. 0.08 μF. This gives a complex impedence of 5320 Ohms and 9° phasor angle, so the coil can be approximated by a resistor, although it is slightly inductive, as one would expect from an armature coil. The windings appear to be from 44 AWG copper magnet wire, but it is hard to say. The wire appears to be finer than human hair, and is so fine that I can only guess 44 AWG because I read that it is somewhat standard, and I have some 30 AWG to compare against.Anyway, I am slightly questioning whether this much series resistance will work for the purpose I intended. I had been naïvely hoping it would come in at, say, 2 ohms. I understand in retrospect thay the best I would be able to buy would be off from that by a factor of 900×, so being off by 2550× is only 3× worse, and definitely puts in perspective how little I knew about these meters, going into this purchase. I see from some listings elsewhere that a 2 Ohm winding is more typical of a meter that measures 3mA full-scale, so a factor of 60× less fine resolution than the 50μA range I wanted. This is obviously a learning experience for me, and the purpose of my review is to make that learning free for those who shop after me. I know $10 is not a huge amount to potentially waste on the wrong meter, but it is still $10 that you could be putting toward the meter you actually hoped to get.As for me, I wonder if I can slap together a current mirror that is microamp accurate, and by so doing, allow this meter to be my panel display, without causing so much of an added resistance to the circuit I have wanted to measure (which is electroplating at near-zero current conditions that hopefully avoid electrolysis of water and dispense with 100% of the current while transporting the electroplating ions and depositing them). In other words, I'm not completely sure I will be able to use this meter for the purpose I had in mind.I gave 3 stars simply because the pre-sales documentation is practically non-existent. Also, because some buyers will search for the lower-rating reviews, and hopefully this one will at least bring some important questions to mind.

Front meter panel had some scratches on both the transparent upper part and the black lower part. I could not polish them away completely. However the movement works fine, so I can still use it.Update: I bought a second meter (identical to above); this one is perfect, and deserves 5 stars.

This unit is ok for a basic project requiring rf readings, but it`s very unstable mechcanically. The movementappears undampened and therefore unusable for mobile use. The meter face appears to be hand stampedwith the "micro" symbol vertically off. It does however display proper readings in circuit. This is a goodbasic unit for the low price, but a higher quality meter would be needed for accurate moble readings.

In low humidity electrostatic force will move the pointer.Took me a while to find it wasn't a circuit problem

Written by the account holder's husband, for whom this was purchased.-------Not the listing's fault, but I didn't notice there are TWO depth listings, and of course in a house with three kids (one of which is a baby), a cat, and constant distractions, it's easy to look at the wrong one and say to yourself, "sure, that'll fit the $10 box I just bought!". I saw the "0.47" inch spec, and didn't notice the "1.9 inch not including screw" spec for actual depth, and ordered a smaller, more affordable box than I shouls have.Of course, the proper fitting box would have been considerably more expensive, so it's a good thing I was able to shave almost a quarter of an inch off the back of this thing with careful cutting and remounting of the rear plate. The rear plate is held on by two tiny screws, so I removed that, cut off about a quarter inch from the main body extension tube, redrilled pilot holes for the screws, and remounted the rear plate. Barely was enough to fit the too-small enclosure.Aside from that, which is my own fault, this meter works fine. I can't speak to the calibration: the project I'm using it for is a radio frequency field strength meter for amateur radio, so current is all relative to infinite variables, however I can say it operates to full scale deflection easily.The mounting is a bit annoying though. I used a metal enclosure and wanted to keep mounting holes small, and so I drilled to fit the main movement cylinder of the meter, not realizing until I was tightening the mounting screws that the back of the meter FACE has its own circular elevation which needs to be accommodated if you want the meter face to mount flush to the panel. Not having a hole saw that big, and not wanting to spend two hours sawing it open by hand with a hobby saw, I made do with the way it currently mounts (about an eighth of an inch gap between the panel and the back of the meter face).On the bright side, it's a class-1.5 meter and was by a considerable amount the least expensive of the bunch I considered. I just wish the meter were a little smaller (didn't realize just how big it was until it arrived) and also the scale card was clearly modified after printing because it has the capital "A" centered on the card in dark, rich, black print and the "u" next to the A was clearly added using something akin to a half-dried-out Sharpie or possibly a rubber stamp. It's aligned well though, so I don't know if it was done by hand, but the "ink" doesn't match the rest of the card. No big deal, it makes no difference in my project, but if you're annoyed by such noticeable modifications then you might want to source a different meter or a way to print your own cards.

Installed this ammeter to measure current flowing through the tube on my laser cutter. It is stable in its operation and works without issue. The little metal studs on the back for attaching leads are a bit small, be careful not to over torque them. It would be nice if it came with a cut-out template for cutting the mounting holes