Student Multimeter? Extech EX330?

[clatella]

Hello All,

Student looking for some opinions on this meter please, (it is an Extech EX330)

http://www.amazon.com/Extech-EX330-Autoranging-Multimeter-Thermometer/dp/B000EX0AE4/ref=sr_1_1?ie=UTF8&qid=1378834084&sr=8-1&keywords=extech+multimeter

My biggest concern is build quality i suppose. As i mentioned I am an engineering student, I dont expect to be dealing with tremendous amounts of power as an electrician would.

Thanks,
Chris

[clifford]

Watch EEVblog #91 - $50 Multimeter Shootout - Extech EX330, Amprobe AM220, Elenco, Vichy VC99, GS Pro-50:



There even is a link to a comparison sheet (pdf) in the video description.

[Wytnucls]

Not a bad little meter, but things have evolved a bit since that shoot-out.
For about the same price, you could get the new UT139C which has a few extra features: 6000 count, true RMS, Max/Min, VFD, better input protection, a separate mA jack and an LCD with a backlight.

http://www.amazon.com/UNI-T-UT139C-Digital-Multimeters-Temperature/dp/B00E3PLSUE

[Lightages]

Everyone seems to forget certain information when asking questions like this. Where do you live? This is needed to help recommend something with local pricing and availability. What is your budget? This is needed so somene doesn't recommend something you can't afford.

Having said that, I would never buy any Extech EX series multimeter. This opinion is based on reviews here, reports of failures, and other information on other sites. It also shares its mA measurement range with the voltage measurement jack which, IMHO, is a recipe for at best blown fuses and at worst blown circuits and/or injuries.

There are few decent choices in the $50 range even if you drop the CATIII requirement.

One would be the Digitek DT-2843R which I have reviewed and is a decent meter for the price.


There is the newly released yet still not well characterized Uni-T UT139C which has been discussed here on this forum. It appears to have decent safety for higher energy circuits, but Uni-T is famous for not respecting the requirements. I seriously doubt that the fuses used are capable of the CATIII tests.
https://www.eevblog.com/forum/testgear/new-trms-uni-t-ut139c-dmm-is-available-now/

A little bit more money, gets you the well known Uni-T UT61E. It has much to recommend it but some things missing like a back light and temperature. There is lots of information here on this meter.

If you want to step up a bit more, $90, then the Amprobe AM-270 is a very good meter except for its lousy joke of a back light.

That's all that can be said until we know the answer to the questions I asked.

[Legit-Design]

UT139C doesn't have double wall for blast protection, see link

The wall is just raised a little bit from input section area. Yes, it has removable rubber holster which might provide some protection if push comes to shove, but I don't think that official way to deal with it.

UT-61D/E have double wall and also that extech EX330 seems to have it.

It all depends on requirements, for bench electronics use UT61E is not that bad meter.

Speaking of backlights UT139C backlight is dependant on battery voltage,  Quote from manual "When the battery supply voltage is reduced to 2.6V, the LCD backlight is weak or can not start; measurement functions can still be used normally"
 I use 2*AA low self discharge NiMh batteries in my UT139C, which are fully charged around 1.2V each, and the backlight is good for really dark environments, but not much else. It's certainly way worse than UT61D which even provides good backlight in bright room environment.

[Dave]

I see a couple of fundamental flaws in EX330's design:

• Milli- and microampere ranges use the same input jack as voltage. Potential safety hazard.
• Resistance, continuity test, capacitance and diode test, all crammed on a single switch position, while frequency/duty cycle takes up its own position and temperature measurement takes up TWO. Really, how often do you quickly have to change between fahrenheit and celsius temperature scale?
• You need to cross the off position while switching between voltage and resistance. Can be annoying.
• When you want to measure milli- or microamps, you have to cross the resistance mode, and because resistance and current jacks are shared, that injects unwanted current into your circuit. You have to keep the leads disconnected before you are in the current range.

[AG6QR]

Milli- and microampere ranges use the same input jack as voltage. Potential safety hazard.[/li][/list]

I'm not sure that's a safety hazard.

Fluke does this with their Fluke 116.   I have no doubt that this industrial service meter designed for HVAC technicians fully meets the CATIII 600V safety standards as Fluke claims.  They also used this strategy with their discontinued Fluke 16, the predecessor to the 116.

The microampere range on these properly protected meters is normally of very high impedance (burden voltage) so it's not really useful for much except testing flame sensor circuits in gas burning appliances.  If you want to measure microamperes on a low power, low voltage circuit, you need to use something like Dave's microcurrent adapter anyway, but that offers no input protection.

By doing it in the Fluke 116 style, you actually avoid the possibility of one common user mistake possible in more typical meters.  That's the scenario where the user was measuring current, and then switches the meter to measure voltage but forgets to move the red lead to the corresponding jack.  You can't make that mistake if there's only one set of jacks.

[Dave]

I was thinking more like switching to resistance while you have it connected to some voltage, and accidentally switching one or two positions too far. Your high impedance input suddenly becomes very conductive.

[Clear as mud]

I blew the fuse on my multimeter because I forgot that it doesn't have a shared terminal for voltage and mA.  I forgot to move the red lead, like AG6QR said.

[Lightages]

Tis last bit of the discussion is beginning to hijack the OP's original question.... but these last posts illustrate why the current jacks should all be done one way and one way only.

[Legit-Design]

UT139C doesn't have double wall for blast protection, see link

double wall -> deep grooves where the case halves meet, is what I meant

Leads on UT139C are different to UT61D/E, still UNI-T branded, tips are very dull, they come with high voltage caps which can be removed. Lead have rated wire "AMW 1803 VW-I 80°C E301305 2000V 18AWG HERWELL" as oppose to UT61D/E which don't have rated wire.

[chibiace]

id recommend saving up for a better meter and get one of those digiteks in the meantime