Digitek DT-2843R AC+DC True RMS multimeter mini review and teardown  - Page 1
Forum section: electronics / testgear

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: January 20, 2013, 09:05:00 am
content: I've had this one for a while but just never had to time to take the pictures and do the write-up. So here are a few pictures and a short summary of my observation.Pros:1. Cheapest AC+DC True RMS meter you can possibly find, with a decent list of features - rel, Max/Min, temperature, backlight, etc. The TekPower TP2844R is almost identical except the lack of temperature measuremet and it's available on Amazon for $39.99http://www.amazon.com/Tekpower-TP2844R-True-RMS-Auto-ranging-Multimeter/dp/B004YF0VEM2. Pretty accurate. Again this is only based on the DMMCheck Plus and PentaRef from VoltageStandard.com that I have, but all the measurements I've done are very well within spec.3. Reasonable build quality. Obviously at this price you're not going to get anything like the Fluke's and Agilent's, but the meter feels reasonably decent in the hand. Range switch clicks and clacks fine. All screw receivers are metal threaded. Ceramic fuse (for 10A range), PTC and MOV present for some basic input protection.4. Does not overshoot.5. I don't have the proper equipment (i.e. a function gen) to test but I can measure DC fairly accurately with the meter set in the AC range so I assume the AC+DC True RMS does work.Cons:1. Glass fuse for the 500mA range. And both fuses are only rated at 250V (which is marked clearly on the jacks).2. Backlight isn't very even, though still perfectly usable.3. Slow auto ranging. Although it doesn't overshoot, it usually takes a second or so for the reading to show up if it needs to auto-range to another range. And during that time the display simply freezes.4. Slow continuity tester.The meter is also rebadged under the Micron brand in Australia (at a higher price).http://www.altronics.com.au/index.asp?area=item&id=Q1074In fact, the particular unit I got from Digitek (as a demo unit) was a Mircon, they just rubbed it off and reprinted the "Digitek" mark on it before they sent it to me.

author: Wytnucls
author_rank: Super Contributor
timestamp: January 20, 2013, 09:59:44 am
content: Nice little meter, Franky. Very good value for money.With TRMS AC+DC, 'Peak hold' would have been nice, but at that price, was understandably omitted.One thing that worries me a bit, is the lack of shielding for the precision resistors and ICs. That could affect your readings in some situations.Good find though and that might be the solution for someone on a budget, looking for extra features, but still happy with a 4000 count meter.

author: Lightages
author_rank: Unknown
timestamp: January 20, 2013, 07:28:46 pm
content: That doesn't look too bad at all for a meter with all those features and for that price. Of course I would not trust it on CATIII/600V use but it looks relatively well protected. Are you going to start carrying this on your ebay store?

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: January 21, 2013, 03:57:04 am
content: I'm actually offering to send this meter to whoever willing to do a video review of this meter. I don't have the equipments and technical knowledge to do a proper one. Any taker? Please contact me if you are interested.Depending on the verdict of the review I might consider stocking these.

author: jarvis
author_rank: Contributor
timestamp: January 21, 2013, 04:29:38 am
content: What's the RMS bandwidth spec. ?

author: Lightages
author_rank: Unknown
timestamp: January 21, 2013, 04:34:53 am
content: I would be willing to do my first video review.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: January 21, 2013, 04:43:55 am
content: Quote from: Lightages on January 21, 2013, 04:34:53 amPlease PM your shipping address.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: January 21, 2013, 04:51:47 am
content: Quote from: jarvis on January 21, 2013, 04:29:38 amhttp://www.digitek.com.hk/en/cpxx.php?id=611

author: castironman
author_rank: Contributor
timestamp: February 01, 2014, 03:16:16 am
content: The TekPower TP2844R also lacks a MOV (CB 102KD14) for input protection...

author: sync
author_rank: Frequent Contributor
timestamp: February 01, 2014, 04:50:57 pm
content: It'sonlyAC+DC, no AC coupled modeThat a big downside. No ripple measurement, etc.

author: Lightages
author_rank: Unknown
timestamp: February 01, 2014, 07:00:42 pm
content: Actually AC+DC mode only is less of a deficit than AC only. If you want to measure AC only then just insert a capacitor in series with the measurement. With AC only you need to make a DC reading and an AC reading and then make some calculations to get True RMS AC+DC.

author: Wytnucls
author_rank: Super Contributor
timestamp: February 02, 2014, 04:11:07 am
content: Quote from: jarvis on January 21, 2013, 04:29:38 amIt is not listed in the specs. It might be written down in the manual. Lightages may have already tested the true RMS bandwidth with his function generator. Give him a bell.

author: sync
author_rank: Frequent Contributor
timestamp: February 02, 2014, 01:53:16 pm
content: Quote from: Lightages on February 01, 2014, 07:00:42 pmThere is a reason why meters like HP34401A, Fluke 87, etc have are AC coupled instead AC+DC. How often do you need AC+DC instead of AC only?AC+DC is nice, but it should be an option.

author: sync
author_rank: Frequent Contributor
timestamp: February 02, 2014, 01:57:18 pm
content: Quote from: jarvis on January 21, 2013, 04:29:38 am1 or 2kHz. Fromhttp://www.altronics.com.au/download/ndb/Instructions/Q/Q1074.pdf:

author: Lightages
author_rank: Unknown
timestamp: February 02, 2014, 06:36:29 pm
content: Quote from: sync on February 02, 2014, 01:53:16 pmWhen you have AC mode only as the only measurement method then you are more limited than with AC+DC. As I said you can measure both AC RMS and then measure DC and calculate but with an AC+DC meter you can insert a capacitor in series with the measurement and have the best of both worlds. If you want a meter that will do both: Uni-T UT71X series, Brymen BM86X BM85X BM52X series, as examples.

author: Lightages
author_rank: Unknown
timestamp: February 02, 2014, 06:40:05 pm
content: Quote from: sync on February 02, 2014, 01:57:18 pmYes, that is the same spec as in the Digitek manual. I have not tested it but with the results of the other tests on the meter I would trust this spec. I will check it later.

author: sync
author_rank: Frequent Contributor
timestamp: February 02, 2014, 09:03:50 pm
content: Quote from: Lightages on February 02, 2014, 06:36:29 pmWon't work for current measurements. For voltage it works with reduced accuracy (doesn't matter for this low end meter). But it is cumbersome and can be dangerous at high voltages. Calculating AC+DC from a AC and a DC reading is easy.QuoteI have two, a POS UT71C and a Datron 1061A. But I use AC+DC very, very seldom. AC coupled is much more important.

author: Lightages
author_rank: Unknown
timestamp: February 02, 2014, 10:03:33 pm
content: Quote from: sync on February 02, 2014, 09:03:50 pmInteresting point and it makes me wonder. When would you do a current measurement in AC and not want to see any DC component? As I write this I can't think of any occasion. Any ideas?Quote from: sync on February 02, 2014, 09:03:50 pmI don't see that any drop in accuracy is necessary. All you are doing is blocking the DC component, assuming the ESR of the capacitor is good. It is not as convenient for sure. Yes it exposes the user to any high voltage dangers if they exist.Quote from: sync on February 02, 2014, 09:03:50 pmWhat is important to you isn't always important to others of course, but I would agree that many times the AC only component of a measurement is what is desired.

author: Wytnucls
author_rank: Super Contributor
timestamp: February 02, 2014, 10:21:08 pm
content: Gossen didn't think that AC only current measurement was important either. On the MetraHit 26S, one gets a choice of DC, AC or AC+DC voltages and DC or AC+DC currents.

author: sync
author_rank: Frequent Contributor
timestamp: February 02, 2014, 10:26:18 pm
content: Quote from: Lightages on February 02, 2014, 10:03:33 pmOk. I don't have any ideas at the momentBut I also wonder what's the use cases for AC+DC voltage measurements in electronics. Heating of course, but what else?QuoteThe problem is the input capacitance of the meter. It builds a capacitive divider with the DC blocking cap. Thus the cap should be big. But then it takes a long time to settle due the meter high input impedance

author: Wytnucls
author_rank: Super Contributor
timestamp: February 02, 2014, 11:50:37 pm
content: Although a dedicated feature would be preferred, Volt AC, if required, can be derived from the same formula Vac=SQRT(Vac+dc^2-Vdc^2)You can keep your cap for other uses.