284d81a7d2
Coupon code knocks it down from AU$17.91 to $8.41
Looks decent enough for hobby and low voltage use, I wouldn't go sticking it in mains supply though.
Excel DT9205A 2.8" LCD Digital Multimeter at Tmart.com - $8.41
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I know nothing of the quality or brands of these things, is this a good buy for around the house? Or can I get one from Masters for similar money if I went looking?
The good:
Has shrouded banana plugs
Appears to have adequate insulation on the leads
Leads have finger-stoppers, to stop your fingers sliding down the probe, although they're a bit smallish.The bad:
The 20A current input is unfused. If you forget the probes are plugged into the 20A input, and then try to measure the voltage of your car battery, you'll have a fire, possibly a small explosion, and burns. Unless you really need to measure currents greater than 200mA, I recommend filling the 20A socket hole with epoxy to make sure it doesn't ever get used. Similar dangers if you leave the probes in this socket and try to measure 240V mains.The 240V warning:
If you have to measure 240V, your leads MUST be in good condition. A pin-hole in the insulation and sweaty hands could kill you, electricity can arc through tiny holes. Preferably measure 240V with one of those plug-in mains power meters that cost about $20 from Aldi or Jaycar - no leads, much reduced danger.
The 20A current input is unfused.
That is bad, but I think you exaggerate.
There will be some arcing at the probe, probably a bang from the meter, and a loss of magic smoke. There is a small resistor in series that will fail quickly.Am tempted to test this with car battery plus old broken meter with shorted fuse. (And safety glasses etc :)
A pin-hole in the insulation and sweaty hands could kill you
exteremly unlikey, but possible. Best to avoid sweaty hands, and hold the probe, rather than the leads.
There is a small resistor in series that will fail quickly.
In all of the multimeters I use, it's a solid bar of metal about 1mm diameter and 25mm long, looks like it could be stainless steel. Admittedly all of those multimeters cost a bit more than $10 each, but this multimeter might use a bit of stainless bar too.
I have seen the result of a Fluke 77 multimeter where this fault happened. The shunt resistor didn't fail, the PCB track right beside it did. But if the track had been a bit thicker, the weakest point could have been the leads themselves, which could get red-hot and melt through their insulation in a second or so.
If the leads are draped over your arm when they get red hot, you'll be really unhappy with the result.
I've made this mistake before, but fortunately only with a single NiCad battery. Nicad batteries can dump 50 Amps into a short circuit, for a short period of time. It didn't melt the wire, but I did burn myself with the probe tip which was hot but not red-hot. Very similar to a soldering-iron burn.
Ouch! Why no fuse in the Fluke?
@manic:
Early Flukes had no fuse on the high-current range. My own Fluke (Fluke 75, 1986 vintage) doesn't. Now all Flukes have fuses on all current ranges - possibly because they were the preferred multimeter for workers in the electrical industry, and it's quite likely a few people died because of the lack of a fuse. If you forget the leads are in the wrong socket, and measure the output of a megawatt-scale transformer, you get a much bigger "bang" than measuring a power point.About the Fluke with the burned-out track: the owner soldered a wire link across the burned-out track, and the multimeter still worked, and was still accurate. This may be one reason why Flukes were a preferred multimeter.
Price comes down to US $6.99(AU $8.41) ;)
Why not? Its the chinese power adapters you should worry about, especially the really tiny ones.
Multimeter does not have the problem of AC->DC isolation failure.