Yeah, I could get one of the cheaper ones, but this was the cheapest I was satisfied with its safety (not perfect though, but at least it's got fused 20A, separate current and voltage inputs, and some sort of input protection for the V/ohm as well, I think).
I'm thinking to get this one:
Lacking backlighting and frequency. On the + side 3999 capability (a better 4 digit readout) which will be nice for current draws.
Haggai, is your VC99 still working well? using the leads that came with it?
It still works well, still reads the same voltage as some other cheap Chinese multimeters I have (but I don’t have other devices that read current or frequency so can’t compare it there).
Not with the original leads, but that’s entirely my fault - I accidentally shorted one lead in a lamp base connected to the mains (220V) so there was a very nice spark and a bit of the coating of the lead chipped off. Nothing happened to the multimeter or to me, though. I replaced them with what looks like an identical pair from GoodLuckBuy and they worked perfectly since. This happened about 6 months after I bought the DMM, so the replacement leads are in use for about a year and a half now.
This multimeter is quite sensitive to the leads used - its ports are deeper than other two el-cheapo DMMs I have, and a bit wider too. This means most MM leads won’t fit or they would wobble. I recently purchased another pair from GoodLuckBuy and they were a little different and they wobble in the ports (that’s the one I bought on both occasions according to GLB’s records: åæ¸ æ¸ ï½è¥¿å交大åæ¸ æ¸ ï½æ±è¥¿æ°ä½åæ¸ æ¸ ï½åä¿¡éé¹äºåå·¥åæ¸ æ¸ ï½åæ¸ æ¸ äººåï½åæ¸ æ¸ ç®å . The first was 20A, the second 10A. But I can’t say anything to GLB because the new ones look very similar to the older ones, and the listing doesn’t specify anything about the leads themselves).
I ordered a new pair from eForChina ( http://www.eforchina.com/v/81628 ). They look different but at least they are rated at 20A and have a “Victor” impression on them so they may fit better. I ordered them about a month ago so they should be here soon.
I also replaced the VC99’s fuses from glass to ceramic, but other than that and the leads it’s still in its original condition and works fine.
I tested it with mains voltage but not mains current IIRC (maybe just once? can’t remember), but used it quite often for current tests on flashlights, no more than about 3A, that’s about the maximum these leads can read in a good day. I did test it with leads made from thick copper wires, these read higher current, but I don’t have a higher current flashlight so I can’t tell how the DMM copes with it.
Hope that helped…
To test this you just need a meter, a formula and some power resistors.
You can get the last items from Hosfelt.com and similar places or you can use several feet of #30 wire or 120v or 12v incandescent. bulbs, the cold resistance of which is 10x or 15x less than the hot resistance, or you can easily make a salt water rheostat.
So… the eForChina leads never arrived and I used PayPal to get a refund.
I then ordered them from sunsky-online (which is actually the same company; I didn’t know that when I made the order), and these took only 59 days to arrive.
They are not a perfect fit but they are better than any other leads I found for the VC99. Didn’t test them for current, but they have about 0.3-0.5 resistance, like the other leads I have.
Maybe Fluke would be best (as this DMM is based on some Fluke design) but I think I’ll just use what I already have.
Only faulty leads has 0.3 to 0.5 ohm, usual it is a factor 10 lower and a good home made lead can be a factor 100 lower.
Using a DMM with 0.1 ohm resolution will always give the wrong answer, contact resistance and offset errors will swamp the result.
I don’t think I ever had any multimeter leads with less than 0.2 ohm resistance… but all I ever had were cheap Chinese leads.
Maybe I don’t measure them like I should - I just touch the leads’ tips when the DMM is on the “ohm” setting. Is this how it’s done?
I need to test the internal resistance of the MM with some thick wire, maybe the leads aren’t the problem here.
Just touching the probe tips will nearly always give a wrong reading.
I have been checking a couple of DMM leads and usual they are in the range of 20 to 60mOhm (0.02 to 0.06 ohm), I had one that measured 157mOhm (That was one of the leads from my UT61E) and my guess is that there is a fault in the lead (The other measured 54mOhm).
So how should I test the leads for resistance?
There is a couple of ways, I have shown one in my DMM guide, here is another:
Sending 1A through the lead and measuring the voltage drop. The actual mV reading is the same as the resistance in the lead, i.e. 32mOhm in this case.
Ah, but I don’t have a power supply… any way to do it without one?
You need a power source, but it does not have to be a power supply, anything with a fairly stable voltage or current can be used (It might even be possible to use a flashlight or just a LiIon battery, but the precision will be lower).
Then you need a known resistor, value depends on your power source.
For test leads you need a test lead socket or it will be impossible to connect to the DMM end of the lead.
And then you need a DMM with milli volt display (Two DMM's are better).
Thanks, I’ll see what I can do when I get back home today.
My time has come to upgrade from 10EUR multimeter, been with that almost 10 years…
I ordered a Fluke 17B+ from Taobao.
Has not arrived yet but teardown reviews look good…