Multimeter

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zoom zoom
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Multimeter

I have seen several posts that go along the same lines as this quote..

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oh yeah, those leads are 

oh yeah, those leads are woefully inadequate

I took an 18ga automotive wire, tinned about 3/4-1” of one end, folded it over to make it double thick re-tinned together (this is the end I slip down into the multimeter plugs) other end I put banana clips, leads are about 12-14” long, those will give you MUCH better readings for sure

 

I have this multimeter now (3 of them actually) it's been good to me so far!.. 

http://www.autohausaz.com/search/product.aspx?partnumber=3320&utm_source...

 

 

My question is, would soldering some 14 ga speaker wire in place of the crap leads be adequate (low enough resistance) for checking low voltage currents? are clips really necessary or would the pointy ends be good enough with a better piece of wire in between?

 

 

are there any quality multimeters I could get for a reasonable price (not 300+) that would do this job and read up to 100A AC?

Edited by: zoom zoom on 01/08/2015 - 15:55
ryansoh3
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14AWG wires are good, especially if you can keep them pretty short, perhaps under 5 inches.

I don’t think any meter can directly read current up to 100A. Try searching eBay for a current shunt or look into getting a clamp meter.

BLF ≠ B-grade Flashlight Forum

 

wight
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Skip the pointy tip business though. Just tin the ends and use the bare wires.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

Billy X
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If you already have 3 “flashlight“multi meters,I would look at a seperate clamp multi meter.Here is the Fasttech page , for instance.I imagine clamp meters are safer.

kuoh
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Careful, only the top 2 Uni-T meters are capable of DC current, the rest are AC only.

KuoH

Billy X wrote:
Here is the Fasttech page , for instance.I imagine clamp meters are safer.
wight
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Billy X wrote:
If you already have 3 “flashlight“multi meters,I would look at a seperate clamp multi meter.Here is the Fasttech page , for instance.I imagine clamp meters are safer.
I’m not certain that I see the angle from which safety becomes an issue? What safety related concerns do we have here?

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

texaspyro
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wight wrote:
What safety related concerns do we have here?

An AC source that can provide 100+ amps can fry you up extra crispy faster than you can say “Oh, crap”. A clamp meter measures current by clamping around an insulated wire. No need to open the circuit and connect the meter to live conductors. Much less chance of you being converted into bacon. Mmmmm…. bacon…..

wight
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texaspyro wrote:
wight wrote:
What safety related concerns do we have here?
An AC source that can provide 100+ amps can fry you up extra crispy faster than you can say “Oh, crap”. [snip]
Show me your 100-amp AC flashlight and I’ll show you mine.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

texaspyro
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I do have a 5000+ amp clamp meter… and have pegged its’ output many times. Also have a milion watt 3 phase power analyzer… unfortunately not big enough to monitor a 10,000 hp diesel-electric set.

My capacitive discharge spot welder can do 20,000 amp pulses. Alas, I don’t have any equipment that can directly measure those. I have fired it into some LEDs before. Turned them into PEDs (plasma emitting diodes).

texaspyro
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AC only clamp meters usually use a current transformer to measure the current an insulated wire is carrying. Clamp meters that can measure DC currents use a hall-effect current sensor. My Tektronix current probes for oscilloscopes combine the outputs of a current transformer and hall-effect sensor and can measure from DC to 100+ MHz.

BTW, the output voltage of an open-circuit winding of an ideal current transformer is … infinite! You don’t want to open-circuit the output of a current transformer…

kuoh
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I would imagine the safety aspect Billy was referring to was more about accidentally shorting something with the probe tips and frying LEDs, drivers or damaging cells, rather than actually hurting people. While what Tex said about the AC stuff is true, in general, it doesn’t really apply to LED flashlights.

KuoH

wight wrote:
I’m not certain that I see the angle from which safety becomes an issue? What safety related concerns do we have here?
wight
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kuoh wrote:
I would imagine the safety aspect Billy was referring to was more about accidentally shorting something with the probe tips and frying LEDs, drivers or damaging cells, rather than actually hurting people. While what Tex said about the AC stuff is true, in general, it doesn’t really apply to LED flashlights.

KuoH

wight wrote:
I’m not certain that I see the angle from which safety becomes an issue? What safety related concerns do we have here?
That may be the case (probably so, but we’ll see if Billy X says differently). If so, I thought it was worthwhile to flesh that point out a bit for those who are still learning. Personal safety / safety from physical harm is something people get very worried about. No need to unduly stir that up!

I agree with you (kuoh), there’s less chance of accidentally shorting something and damaging flashlight components when you’re using a clamp rather than handheld probes. OTOH the clamp requires more setup in order to see that advantage. Cheap modded meters are mostly not dangerous to your parts and are (IMO) not in any way significantly dangerous to your health / well being when used on normal modded flashlights. If you get into extreme high power mods any danger won’t be coming from the meter: it’ll be coming from the hardware itself.

I’d hate to give people the idea that a modded $10 meter isn’t good enough from a safety perspective and that they need $50-100 DC clamp meters for our purposes. I don’t think it’s the case (but of course I’m willing to hear it out if someone has a legit safety concern).

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

WarHawk-AVG
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texaspyro wrote:
wight wrote:
What safety related concerns do we have here?

An AC source that can provide 100+ amps can fry you up extra crispy faster than you can say “Oh, crap”. A clamp meter measures current by clamping around an insulated wire. No need to open the circuit and connect the meter to live conductors. Much less chance of you being converted into bacon. Mmmmm…. bacon…..


Frying you isn’t the part that kills you…the miniscule milliamps stop your heart, if your pumper ain’t pumpin’ you’re having a bad day Silly

With that said…turning into a pile of smoky charcoal is definitely not a good way to go for sure…makes a HECK of a mess, and the smell :Sp

Bad part is 110~ makes your muscles constrict…grab the wrong wire and you CAN’T let go…at least 200V or higher it likes to toss you away from it (I found out the hard way when I touched the flyback port terminals on a 25” color TV screen I thought I had discharged…waking up about 8 feet away laying in a pile of safety glass after being tossed away was NOT a fun experience)

As wight said though…our hobby unless we are playing with mains rectifiers or something we just don’t see the voltages that do make us crispy critters, I’m more worried about burning myself with a soldering iron or breathing all those daggum fumes

Billy X
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Zoom Zoom had a 2 part question.The first part was about short , thick , low resistance dmm cables.I didn’t respond to that.
The second part

Quote:
are there any quality multimeters I could get for a reasonable price (not 300+) that would do this job and read up to 100A AC?
was what I was referring to and I replied
Quote:
If you already have 3 “flashlight“multi meters,I would look at a seperate clamp multi meter
.Please note the seperate or should it be separate :p.He or she Wink already hes 3 Innova dmms and a $12 to $40 clamp meter just for 100A AC is a lot better than 300+ .
BTW,the FT link was purely because the ad was sitting there on my left while writing,so I used it to link to their clamp dmms.
100 amps at 110 volts , that’s 11kW and a probe meter is in series.I don’t want to be holding those probes when a car exhaust backfires outside Shocked
I hope this clears up any confusion.
LazyJ
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I recently got that version of the Innova and really like it. The battery test function is handy and actually works very well.

wight
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Billy X wrote:
Zoom Zoom had a 2 part question.The first part was about short , thick , low resistance dmm cables.I didn’t respond to that.
The second part
Quote:
are there any quality multimeters I could get for a reasonable price (not 300+) that would do this job and read up to 100A AC?
was what I was referring to and I replied
Quote:
If you already have 3 “flashlight“multi meters,I would look at a seperate clamp multi meter
.Please note the seperate or should it be separate :p.He or she Wink already hes 3 Innova dmms and a $12 to $40 clamp meter just for 100A AC is a lot better than 300+ .
BTW,the FT link was purely because the ad was sitting there on my left while writing,so I used it to link to their clamp dmms.
100 amps at 110 volts , that’s 11kW and a probe meter is in series.I don’t want to be holding those probes when a car exhaust backfires outside Shocked
I hope this clears up any confusion.
Good enough for me! Thanks Billy X.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)