Author Topic: Update in OP: Help selecting cheap DMM  (Read 3832 times)

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Offline KILLSWITCHTopic starter

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Update in OP: Help selecting cheap DMM
« on: April 09, 2018, 05:48:31 pm »
UPDATE: Meter came in.
Feels cheap, seems accurate within specs when taking static measurements.
Dynamic measurements - Screen updating is slower than I like. During PWM, changing digital or analog measurements it cant keep up with the Fluke and affects the value reading which doesn't agree with the Fluke  :palm:
The probe tips had a little corrosion and maybe some special chinese sauce on them throwing measurements off and giving slow, inconsistent continuity readings. I cleaned them with some metal polish and they work great now.
The extra probes/accessory pack was nice to get and has been useful. The pouch was thicker and better quality than I thought it would be.
I like the big 9999 count display.
Overall for the price its a good hobby meter [maybe best in this price range] but not fast enough for dynamic circuit measurement IMO and the mA accuracy hole is dissapointing.


I'm starting an electronics self study book and need a second DMM for low power project measurements.

I have a Fluke 177 but need a second DMM with a good uA-mA and mV range.
I'm on a tight budget and would like to keep the cost under $35 if possible.
 
I will be starting with basic DC/AC (RLC circuit measurements, transistor circuit biasing measurements etc) and eventually get into logic and microcontrollers if that helps.

What would you suggest?
« Last Edit: April 22, 2018, 08:19:44 pm by KILLSWITCH »
 

Online ataradov

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Re: Help selecting cheap DMM
« Reply #1 on: April 09, 2018, 05:57:58 pm »
UNI-T UT136, if you are not a snob and don't want to overpay for marketing.
Alex
 
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Offline KILLSWITCHTopic starter

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Re: Help selecting cheap DMM
« Reply #2 on: April 09, 2018, 06:11:12 pm »
Wouldn't a UT139C be a much better value for an extra $15?
Larger screen, better resolution, lights LEDs and shows Vdrop, standard AA batteries, rel function etc.

I should have mentioned I would like to get the best value meter in this price range as I would like to use the meter for other stuff but it must be able to measure in the ranges stated above as that is what I'm lacking and needing.

I have looked around and I keep coming back to the UT139C and AN8008 but would like a sanity check on these choices and see if I missed another meter worth considering.
 

Online ataradov

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Re: Help selecting cheap DMM
« Reply #3 on: April 09, 2018, 06:30:19 pm »
I like UT136 for its size. It is very convenient as a secondary meter (actually primary for most stuff in my case).  UT139C is also good, it was more expensive when I got mine. For $35 it is a good value as well.
Alex
 

Offline nctnico

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Re: Help selecting cheap DMM
« Reply #4 on: April 09, 2018, 06:36:52 pm »
A used HP 3466A perhaps?
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Offline KJDS

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Re: Help selecting cheap DMM
« Reply #5 on: April 09, 2018, 07:29:28 pm »
A used Fluke 25


Offline GreyWoolfe

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Re: Help selecting cheap DMM
« Reply #7 on: April 09, 2018, 07:39:55 pm »
A used HP 3466A perhaps?

You won't find one that cheap on evilBay with the possibility of returning it if it doesn't work and you can't fix it.  $75-$80 USD and up for one you can return.  The one I picked up off of evilBay was about $60 USD I believe.  KILLSWITCH, if you do decide on the HP 3466A, be aware that most probably work fine, but the indicator LEDs will probably not match the function selection.  Both of mine were like that.  A judicious amount of contact cleaner and lots of button pushing fixed that.  This being said, you may get a deal on one that the person doesn't know about this issue/fix.

Here is one that shows mA selected but k\$\Omega\$ LED lit.  It also has a make offer button.  You might get away with a lower offer if the seller hasn't a clue.  https://www.ebay.com/itm/HP-HEWLETT-PACKARD-3466A-DIGITAL-MULTIMETER-A2/222772406097?hash=item33de452751:g:8ucAAOSwovNaRDxD   I'm not interested as I have 2 of these already.
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Offline KILLSWITCHTopic starter

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Re: Help selecting cheap DMM
« Reply #8 on: April 09, 2018, 10:46:01 pm »
While I prefer quality stuff I'm going to stay away from used stuff for now to ensure I get a working meter with leads with warranty in my limited price range.

So the last link provided by IanB says the 139C (and many other) Uni-T meters have high burden voltage in the upper mA range  :palm:

I know there is a hole in the AN8008 mA range which will measure the current I'm needing this meter for but with low accuracy. The build quality 'appears' worse than the 139C.

So my options are high burden voltage in high mA range (UT139C) or precision gap in the mA range (AN8008).
Any thoughts on one flaw VS the other?
I'm guessing low resolution is better than scewed measurements?
 

Online ataradov

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Re: Help selecting cheap DMM
« Reply #9 on: April 09, 2018, 11:11:36 pm »
So the last link provided by IanB says the 139C (and many other) Uni-T meters have high burden voltage in the upper mA range  :palm:
It is not any higher than any other general purpose multimeter.  Is there any information that AN8008 has better burden voltage?
« Last Edit: April 09, 2018, 11:21:59 pm by ataradov »
Alex
 

Offline Lightages

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Re: Help selecting cheap DMM
« Reply #10 on: April 09, 2018, 11:20:50 pm »
If you already have a multimeter and are looking for better current measurement then consider uCurrent from Dave.

Otherwise I will go with the devil I know, UT139C
« Last Edit: April 09, 2018, 11:22:46 pm by Lightages »
 

Offline RobertPS

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Re: Help selecting cheap DMM
« Reply #11 on: April 10, 2018, 12:05:48 am »
How about the Aneng AN870?
It has all the ranges you want and you can get it below $28.
 

Offline KILLSWITCHTopic starter

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Re: Help selecting cheap DMM
« Reply #12 on: April 10, 2018, 12:25:26 am »
So the last link provided by IanB says the 139C (and many other) Uni-T meters have high burden voltage in the upper mA range  :palm:
It is not any higher than any other general purpose multimeter.  Is there any information that AN8008 has better burden voltage?
Here is the link to the 139C and AN8008
https://lygte-info.dk/review/DMMAnengAN8008%20UK.html

https://lygte-info.dk/review/DMMUNI-T%20UT139C%20UK.html

Look at the bottom of the chart posted before the tear down photos.
 

Offline KILLSWITCHTopic starter

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Re: Help selecting cheap DMM
« Reply #13 on: April 10, 2018, 12:31:13 am »
How about the Aneng AN870?
It has all the ranges you want and you can get it below $28.
I looked for information on that meter but cant find much.
From what I could find it looks like a 8008 in a different case, but like I said I couldnt find much about it.

I was able to find this post about this meter:
https://www.eevblog.com/forum/testgear/another-cheapo-multimeter-19999-count-0-05-dc-accuracy/
 

Online ataradov

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Re: Help selecting cheap DMM
« Reply #14 on: April 10, 2018, 12:59:07 am »
Look at the bottom of the chart posted before the tear down photos.
Good. Then it is time to also pick up AN8008.
Alex
 

Offline KILLSWITCHTopic starter

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Re: Help selecting cheap DMM
« Reply #15 on: April 10, 2018, 02:15:09 am »
AN8008 ordered.

It seemed to meet my requirements closer than the UNI-T.
I also needed a second meter so the uCurrent wasn't an option this time around.

Thank you to everyone who commented.
 

Offline rhb

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Re: Help selecting cheap DMM
« Reply #16 on: April 11, 2018, 12:07:10 am »
 

Offline KILLSWITCHTopic starter

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Re: Help selecting cheap DMM
« Reply #17 on: April 11, 2018, 03:08:22 am »
Are you spying on me  ;D
It just so happens I have two meters, one a Fluke, the other a Cen-Tech.
I 'inherited' the Cen-Tech from my brother when he got it free at HF.
I assumed it was junk and never bothered to use it or check its accuracy.

After going through the thread you linked I opened mine up and it has the trim pot  :-+
A quick and dirty adjustment of the pot got me within 1m \$\Omega\$ of the Fluke.
Compared to the Fluke in a limited test I'm getting 80µA and 10mV difference. My connections are suspect so it mostly likely is better under more controls conditions.
The resolution is such that I may be getting better mV accuracy but I cant see it.
These results are much better than I expected and a welcome surprise.

Thanks for letting me know.
 

Offline joseph nicholas

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Re: Help selecting cheap DMM
« Reply #18 on: April 11, 2018, 11:37:14 am »
Some notes on the cheap Cen tek meters,

While these things have not bad accuracy they dont measure ac amps, which will be annoying if you want to measure what some ac device is drawing.

They dont measure into the high ohms range and so you'll need to get another meter out for this.

The problem with the test leads can be remedied by putting a dab of glue on where the lead enters the probe, as users tend to twist the probe wires back and forth during measurements and without strain relief at the joint the wires break.

Hope this helps.

   

 

Offline rhb

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Re: Help selecting cheap DMM
« Reply #19 on: April 11, 2018, 12:37:42 pm »
Thanks for the tip on the probes.  That's a great idea.  Hot melt glue on the way.  The usual failure is the solder joint at the tip connection.

I had always assumed that the Cen-Techs were only good to 1% or so.  I was rather surprised by the results of my test.  True they have limitations, but even at $6  they are hard to beat.    One does need to remember to correct for the 1 Meg input impedance if you need precise measurements.

The main reason I like them is I can keep one everywhere I might need a DMM.  I'm still using the ones I bought for $3.  I've been collecting the free ones to give to kids who show an interest in electronics.
 

Offline joseph nicholas

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Re: Help selecting cheap DMM
« Reply #20 on: April 11, 2018, 04:44:42 pm »
Thanks for the tip on the probes.  That's a great idea.  Hot melt glue on the way.  The usual failure is the solder joint at the tip connection.

A lot of these probes are shipped with cheap meters.  There is a gap where the wire enters the probe.  The probe is a bad design but if you do the glue thing the probes work for along time.  For some reason there is a film of something smeared on the probes so this needs to be cleaned off to get better continuity.

For few dollars more, the Dt 90xx or something would be a better gift for the new learners.  If you get a good one it will give capacitance, temp, hz etc.  You can also put in a led, if it doesnt come with one by drilling a small hole in the front panel.  It has 3 trim pots for calibration so drill a few holes in the front panel to get a screwdriver in and you can compensate if the dc and ac volt ranges are off.  When calibrating, dont use line voltage as a safety precaution.

 


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