RICHMETERS RM158D  60.000 counts - Page 1
Forum section: electronics / testgear

author: Jon.C
author_rank: Unknown
timestamp: February 26, 2025, 01:51:28 pm
content: interesting? I don't know, I haven't seen any reviews yetRICHMETERS RM158D60,000 counts on aliexpress about 35 €https://www.youtube.com/shorts/5XmI47gAupY

author: Aldo22
author_rank: Super Contributor
timestamp: February 26, 2025, 06:04:03 pm
content: Hmm, 60000 counts but +-10 digits accuracy? Does that make sense?I think I prefer the ZT-225 with 25499 counts and +-3 digits.

author: puxe
author_rank: Contributor
timestamp: February 27, 2025, 09:16:27 am
content: I have been looking at this meter too and wondering about the resolution Vs accuracy.I have the NJTY T58C which is an autoranging 9999 count meter with induction measurement. I like the handling, speed, display, etc. and have just ordered the T58A too, which is manual ranging with Loz and a few other features, such as transistor and infrared detector. Cheap as chips and work well IMO.These also come as Habotest, AstroAI, Richmeters and possibly a few other variants too. They have just been tested on the ongoing meter robustness thread.For anything above normal domestic mains voltage, I would use my Amazon CEM meters..... just to avoid the CAT safety related debate on cheap meters.

author: JoanBS
author_rank: Contributor
timestamp: February 27, 2025, 10:06:09 am
content: I don't see the advantage of this meter having a 5-digit resolution with a +10 digits accuracy. Basically it would be like a 6000 count meter, although for the price you can't ask for much more...

author: puxe
author_rank: Contributor
timestamp: February 27, 2025, 11:41:43 am
content: Quote from: JoanBS on February 27, 2025, 10:06:09 amThat's the question ...Some meters like the Aneng SZ20 25000 count have DC accuracy specs like 0.2%+10 .... too.

author: Aldo22
author_rank: Super Contributor
timestamp: February 27, 2025, 11:48:20 am
content: Quote from: puxe on February 27, 2025, 11:41:43 amNot true, SZ20 / ZT-225 has DC voltage accuracy: ±(0.05%+3)

author: puxe
author_rank: Contributor
timestamp: February 27, 2025, 12:44:09 pm
content: Quote from: Aldo22 on February 27, 2025, 11:48:20 amI don't actually have this meter and sourced my spec info from the AliExpress Aneng official store:±(0.2%+10)https://www.aliexpress.com/item/1005005492526138.html?spm=a2g0o.cart.0.0.7ec838daAv6HnU&mp=1&pdp_npi=5%40dis%21GBP%21GBP%2056.20%21GBP%2026.15%21%21%21%21%21%40211b61a417406562131738693e9b93%2112000033294866943%21ct%21UK%212940900060%21%211%210The AN870 19999 count DCV specs looked better when I was comparing specs across the cheap meters:±(0.05％+ 3)

author: Aldo22
author_rank: Super Contributor
timestamp: February 27, 2025, 01:27:45 pm
content: Quote from: puxe on February 27, 2025, 12:44:09 pmI have a ZT-225 and I tend to believe the specifications in the official manual:

author: puxe
author_rank: Contributor
timestamp: February 27, 2025, 01:37:29 pm
content: Quote from: Aldo22 on February 27, 2025, 01:27:45 pmInteresting indeed.The other possibility is that the SZ20 is a lower spec than the ZT-225?There was some testing conducted recently on keepontesting.com :https://www.keepontesting.com/post/error-chart-compilation-dc-voltageThese NJTY/Richmeters/AstroAI/Habotest etc. look very similar to the ZT-225/SZ20, so quite possibly from the same stable. I guess teardowns would have to consider the ADCs etc to confirm.

author: Aldo22
author_rank: Super Contributor
timestamp: February 27, 2025, 01:53:07 pm
content: Quote from: puxe on February 27, 2025, 01:37:29 pmThere has already been speculation about this.However, they have the same PCB and serial number.Quote from: puxe on February 27, 2025, 01:37:29 pmI don't think so. Aneng and Zoyi yes (Zotek), maybe Richmeters. The others imo no.

author: wasedadoc
author_rank: Super Contributor
timestamp: February 27, 2025, 02:02:44 pm
content: Quote from: puxe on February 27, 2025, 01:37:29 pmI have both a Habotest 118E and an Aneng SZ20. They are similar shape but very different internally. 2 AA cells in the former, 3 in the latter. 20,000 counts vs 25,000. SZ20 has AC+DC Volts RMS. Tilting bale is different construction. Flashlight in different place. Etc. Don't look like from same factory to me.

author: puxe
author_rank: Contributor
timestamp: February 27, 2025, 02:03:42 pm
content: Quote from: Aldo22 on February 27, 2025, 01:53:07 pmI reckon the Richmeters and NJTY are definitely from the same source.The features, layout and specs of the RM158D and T58D are identical AFAIK. I don't have these, to check for sure...Edit - corrected from RM113D to RM158D

author: Aldo22
author_rank: Super Contributor
timestamp: February 27, 2025, 02:12:52 pm
content: Quote from: puxe on February 27, 2025, 02:03:42 pmRichmetershas DMMs, which are obviously fromZotek(Zoyi, Aneng), but the RM113D is not imo.In any case, I've never seen it under the Aneng or Zoyi brand.

author: puxe
author_rank: Contributor
timestamp: February 27, 2025, 02:32:33 pm
content: Quote from: Aldo22 on February 27, 2025, 02:12:52 pmSorry - I have mixed part numbers up ...The Richmeters RM158D and NJTY T58D are identical 60000 count meters with illuminated jack sockets, Peak button, LCD auto light-on, fuse location/spare holders, 3 AAA batteries, etc......As far as I can see.https://www.aliexpress.com/item/1005008248063702.html?spm=a2g0o.cart.0.0.7ec838daAv6HnU&mp=1&pdp_npi=5%40dis%21GBP%21GBP%2046.14%21GBP%2023.09%21%21%21%21%21%4021038da617406539322103918eda40%2112000044371492092%21ct%21UK%212940900060%21%211%210https://www.aliexpress.com/item/1005007423661387.htmlThe other variants eg T58B 9999 count look like there are similar matching models too

author: ftv
author_rank: Newbie
timestamp: February 27, 2025, 06:53:31 pm
content: It's just a scam. I bought NJTY T58D, according to me it's exactly the same thing as RM158D, only it's orange instead of red :-). The specs are nonsensical, in my opinion the table is just wrong in the DC voltage section.Anyway, the devicedoesn't have60000 digits, it lacks the necessary resolution. In the DC voltage range the last digit jumps by two, so at best it has 30000 digits. For example, my unit never shows 10.000 V, 9.999 is followed by 10.001, and that's how it behaves throughout the whole range.You can see this behavior well in that short video:https://www.youtube.com/shorts/5XmI47gAupYat 0:30 and 0:42.The DC voltage accuracy is about on the edge of 0.05% compared to my HP3478a and HP3457a.The resistance is OK, the last digit really changes by one.DC current - last digit jumps sometimes by one, sometimes by two. However, my unit is out of spec, at 1 A it has an error of about 1.2% if I remember correctly.I also noticed that on Aliexpress both the NJTY T58D and RM158D have disappeared from the listings ...If anyone is interested, I can take it apart and take pictures, but I don't see any point in doing it ...Translated with DeepL.com (free version)

author: JoanBS
author_rank: Contributor
timestamp: February 27, 2025, 07:21:45 pm
content: Quote from: Aldo22 on February 27, 2025, 01:27:45 pmBased on my experiences with chinese products, I don't believe anything they say. I recently bought a box of 0.1% tolerance resistors on Aliexpress and when I measured one of the 100 ohms ones it read 101.5 ohms. I think this is more than 1%, not 0.1%...

author: Aldo22
author_rank: Super Contributor
timestamp: February 27, 2025, 07:37:28 pm
content: Quote from: JoanBS on February 27, 2025, 07:21:45 pmI don't know what's wrong with your resistors, but my ZT-225 measures as accurately as stated in the specifications, as far as I can tell.

author: JoanBS
author_rank: Contributor
timestamp: February 27, 2025, 07:44:44 pm
content: Quote from: Aldo22 on February 27, 2025, 07:37:28 pmI'm happy for you. In fact, I just bought one of those cheap multimeters myself...

author: FixyMixy
author_rank: Contributor
timestamp: February 27, 2025, 08:18:22 pm
content: Unfortunately, there is no reviews on this device.It's interesting what's inside. My two ZT219 start to glitch because of bad main switcher contact (main board has no golden cover).

author: Aldo22
author_rank: Super Contributor
timestamp: February 27, 2025, 08:21:42 pm
content: Quote from: JoanBS on February 27, 2025, 07:44:44 pmYes, I must be a lucky man!I have a cheap Chinese DMM and cheap Chinese 1% resistors, but I can't complain.

author: puxe
author_rank: Contributor
timestamp: February 27, 2025, 08:25:18 pm
content: Quote from: ftv on February 27, 2025, 06:53:31 pmThe quoted spec for DCV is 0.5% +/-10 counts, so that is a good result and well within spec.IIRC The testing from keepontesting.com demonstrates that there seem to be many low cost meters that mostly perform to their specs or better ..... IMO that's good as it means it is not necessary to expend large chunks of cash to acquire an instrument that does the job that it was intended for.Today hobbyists can buy cheap meters, oscilloscopes and other useable kit that would have cost a small fortune only a couple of decades ago.

author: Aldo22
author_rank: Super Contributor
timestamp: February 27, 2025, 08:40:22 pm
content: Quote from: puxe on February 27, 2025, 08:25:18 pmNo, that's for DC current.DC voltage is specified for the RM158D as +-(0.05% + 10) for 1V to 600V ranges.

author: puxe
author_rank: Contributor
timestamp: February 27, 2025, 08:51:41 pm
content: Quote from: Aldo22 on February 27, 2025, 08:40:22 pmSorry, yes you are correct, and the meter would thus meet its spec.

author: ftv
author_rank: Newbie
timestamp: February 28, 2025, 12:11:05 am
content: I repeat, this device is complete nonsense because the HW apparently doesn't have enough resolution for 60000 digits. Someone just decided to milk the T58A (T58B, T58C) design and make it into something it can't be.I wonder if the T58C really displays the 1-10 V range with 1 mV steps. If so, then the T58D is actually worse, because as you can see in the attached video,it goes 9.991, 9.993, 9.995, 9.997. 9.999, 10.001, etc. And so it is throughout the entire DC voltage range. DC current works similarly, only resistance works properly.Not to mention that the bargraph is of course "fake", i.e. it refreshes at the same frequency as the digits, making it absolutely useless.

author: Aldo22
author_rank: Super Contributor
timestamp: February 28, 2025, 09:46:03 am
content: Quote from: ftv on February 28, 2025, 12:11:05 amSo the resolution would be more like 0.002V in this range?Otherwise it's actually within spec in terms of accuracy, as with +-10d the last digit can be almost random.What does it do at the range limits? Does it show 6.0000V or 6.000V?Are at least the mV below that correct, e.g. 5.900xV?But yes, the 60000 counts probably don't make that much sense here.

author: ftv
author_rank: Newbie
timestamp: February 28, 2025, 03:45:50 pm
content: Transition from 0.6-6V to 6-60V range:https://youtu.be/-ezflglc72sUnfortunately I don't have precision voltage source, so I used RD6006P set to circa 60V with a voltage divider increasing the voltage in 1 mV increments. That's why it's all so noisy. When changing the range (time 0:20), voltage drops by 2.5 mV, because T58D has an input impedance of 11 MOhm in the 0.6-6V range but only 10 MOhm in the 6-60V range.Anyway, my advice is: don't buy it, it's a scam. Or take it as an overpriced 6000 digit device that has the last digit merely as an indicator. In fact considering it a 6000 count device it is not bad at all. But the last digit jumping by two is really annoying and reminds you that you have been fooled by marketing bullshit :-(

author: Aldo22
author_rank: Super Contributor
timestamp: February 28, 2025, 04:55:53 pm
content: Thank you.It's probably acceptable for the price, but with 60,000 counts you'd expect something better.I think AN870 or ZT-225 are more serious in terms of accuracy specifications.

author: puxe
author_rank: Contributor
timestamp: February 28, 2025, 05:26:19 pm
content: Quote from: Aldo22 on February 28, 2025, 04:55:53 pmI intentionally didn't buy the 60000 count Richmeter/NJTY because I suspected the last digits would be nothing more than just noise. The 9999 meters seem quite good as far as I have seen so far (not tested in any detail).Do you believe the SZ20/ZT-225 can make full use of the 25000 count and maintain accuracy & stability ? .... or does the last digit wander somewhat tooMy CEM (Amazon) 50000 meter is not rock solid, but is probably fairly good compared to the less costly meters.

author: Aldo22
author_rank: Super Contributor
timestamp: February 28, 2025, 05:49:14 pm
content: Quote from: puxe on February 28, 2025, 05:26:19 pmIt does not wander.At most it is a little undecided by 1 digit. E.g. 10.000V -> 10.001V, but that doesn't bother me.In any case, 1mV steps are visible in this case. So it does not jump in 2mV steps like the RM158D.Of course it's not perfect, but for the $27 I paid, it's surprisingly good (ZT-225).

author: ftv
author_rank: Newbie
timestamp: February 28, 2025, 06:31:12 pm
content: Quote from: Aldo22 on February 28, 2025, 04:55:53 pmAbsolutely.In general, from my experince, all multimeters are a mixed bag of good and bad, none is ideal.For example, AN870, which I also have, has the invaluable advantage that I can adjust it myself. As well as the AN8008 and Owon XDM1241, also in my possession.On the other hand, it (and AN8008 as well) has bad input protection and drifts severely thermally when measuring current. XDM1241 has problems when measuring temperature and is useless for capacitors. AN8008 has a big hole in current ranges, missing 1-10mA and 10-100mA. UNI-T UT60BT has a similar flaw, but otherwise I liked it enough to have 3 of them.Its advantages:1) by far the best continuity testing which I ever saw, on top of that at first position on rotary switch2) beeps when measuring diodes3) really fast and accurate voltage, current and resistance measurements. Two of mine don't differ on the DC 1-10V range from the HP3478 by more than 1mA, the third is a little worse but still within spec4) NCV has two sensitivity levels, so it can filter out ghost voltages when testing mains socket5) Bluetooth works well for connecting to my PC, as I reverse engineered the communication protocol and wrote an app to display the measurements6) Measures small capacitors down to picofarads7) sturdy construction8 ) low power consumption9) relatively inexpensive, I got them for $25-30Disadvantages:1) missing current ranges2) really bad (dimm) display backlight, which turns itself off after about 20 seconds. It's so annoying that I decided to fix it myself, but I haven't finished this project yet3) in the microamp range they put a PTC with a resistance of several hundred Ohms in series with the shunt, which is supposed to be 100 Ohms!!! So the device was showing total nonsense. I fixed it by swapping PTC for one with less resistance and adding a potentiometer to trim it. What is funny and sad, nobody noticed such a serious shortcoming (and I saw 3 or 4 video reviews of this device).

author: Aldo22
author_rank: Super Contributor
timestamp: February 28, 2025, 06:59:16 pm
content: Quote from: ftv on February 28, 2025, 06:31:12 pmYesterday I took a look at the resistances in the A, mA, μA measurements of the ZT-225:A: 0.1ΩmA: 1.5ΩμA: 100ΩThe good thing about 4.5 digits is that you can still (just) measure e.g. 0.5mA in A mode (burden voltage).

author: ftv
author_rank: Newbie
timestamp: February 28, 2025, 07:37:15 pm
content: Quote from: Aldo22 on February 28, 2025, 06:59:16 pmYes, those are commonly used values in DMMs, I think.Quote from: Aldo22 on February 28, 2025, 06:59:16 pmIt is reason that I did not sell the T58D yet. I am considering to use it to current measurements, because by trimming shunts I could be perhaps able to adjust it to be quite precise(?), andit has here little bit better resolution than on voltages; last digit jumps like three times by two and one time only by one or so.

author: lehkohod
author_rank: Newbie
timestamp: July 06, 2025, 10:02:51 am
content: Quote from: ftv on February 28, 2025, 06:31:12 pmI have two AN870 and I am always interested in learning about hidden functions of these budget but very decent multimeters.Can you tell about the procedure for calibrating the AN870?I know thatthere are jumpers JP2 and J1 on the board, but I am not sure that it is possible to calibrate the AN870 with them, and how to do it.It says here, without going into details, that can be "shorted a jumper inside" to activate the calibration mode.This is about J1/JP2 jumpers.And here Gandalf_Sr tried to calibrate with these jumpers.But I think it is still worth to ask.

author: ftv
author_rank: Newbie
timestamp: July 07, 2025, 12:13:58 pm
content: https://www.eevblog.com/forum/testgear/calibration-of-an-aneng-an870/msg5969793/#msg5969793