Milliamps, Microamps, and True-RMS

[Merkava_4]

I've been looking at different multimeters on the internet and I gotta couple of questions:

1. How important is it to have Milliamp and Microamp functions?

2. How important is it to have the True-RMS capability?

Some multimeters will have Milliamps and Microamps, but no True-RMS.

Some multimeters will have True-RMS, but no Milliamps and Microamps.

 

[tcp71]

What are you using it for? How much do you want to spend? Electronics board level troubleshooting will require milliamperes. General home and auto work a regular amp setting and true rms(for home) is useful.

 

[zrxkawboy]

1. It simply depends on whether you need these ranges.

2. The true-RMS capability assures the accuracy of non-sine wave AC voltage readings. A non-true-RMS meter will calculate RMS voltage based on a perfect sine wave, so the further a waveform is from a sine wave, the less accurate the reading will be. A true-RMS meter will display the correct RMS voltage regardless of the waveform being measured.

 

[Merkava_4]

Originally Posted By: tcp71
What are you using it for? How much do you want to spend?


I need it for testing automotive OBD-II circuits. I wish I didn't have to spend more than $125.

 

[edhackett]

This looks promising. It has everything you would likely ever need; TRMS, uA, mA, temp, frequency, etc., and a ~$85 street price. It's not a Fluke, but is far from junk.

http://www.extech.com/instruments/product.asp?prodid=272

Ed

 

[punisher]

For automotive use, true RMS is not necessary. If you have the budget, fine, if not, don't let it be a dealbreaker.

Milliamp is a must. Sometimes you have to trace low current draws, and 10-20 mA is the difference between pass/fail.

If you can get a clamp on DC ammeter as well, even better. Comes in handy to diagnose alternator output and starter draw.

I picked up a AC/DC clamp on ammeter/multimeter combo a couple years ago and it is my go to diag tool. Not enamored with the mA capability though, so I sometimes break out the trusty old Fluke 88.

 

[901Memphis]

I have the Extech MN35 and the EX330 has to be much better. The MN35 seems to be darn accurate. The hold feature is nice too.

 

[Mr Nice]

I have a Fluke meter from work but Ive seen a BITOG member have a low cost meter he uses for automotive repairs that was quite handy.

I think it was JHZR2 with the low cost meter.

 

[Y_K]

be careful with extech, you get what you pay loved comments with resoldering itself with 10A jolts. OTOH it may be good enough for an amateur

 

[sleddriver]

Thanks for posting that link. I linked over to some videos and some others as well. What a shame more simple electronics isn't going on in jr. high & high schools.

 

[Quest]

for automotive testing (general stuff), uA is not needed.

mA is commonly used, as in 5A, 10A DC capability.

true RMS may not be needed for you are mostly dealing with DC issues (true RMS is for dealing with AC-related measurements, where sine-wave is of reference).

Q.

 

[wokeupdead]

For intermittent home use, a ten dollar one from Wal mart would suffice. You don't have to be precise to ten thousandth of a volt. I use one even in the shop when I don't want to bring out the big meters or oscilliscope.

 

[1 FMF]

Originally Posted By: Merkava_4
Originally Posted By: tcp71
What are you using it for? How much do you want to spend?


I need it for testing automotive OBD-II circuits. I wish I didn't have to spend more than $125.


you should be fine with a craftsman multimeter from sears, they are $50 or less. I prefer the autoranging ones, which are $50.

it sounds like for what you are doing or want to do, you don't need anything offering true rms.

http://www.newark.com/pdfs/techarticles/fluke/whyTueRMS.pdf
http://www.testequipmentdepot.com/applic...s-matter_an.pdf