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EEVblog => EEVblog Specific => Topic started by: miceuz on March 04, 2014, 06:54:19 pm

Title: You need at least 4 multimeters?
Post by: miceuz on March 04, 2014, 06:54:19 pm
Does anyone remember in which episode Dave talks that you need at least 4 multimeters? One my friend just got caught by burden voltage trap, I want to give him some additional food for thought  ;D
Title: Re: You need at least 4 multimeters?
Post by: hans on March 04, 2014, 08:12:33 pm
Episode 110, let's design a SMPS @ 31:20

It was about the efficiency Dc/Dc converter, so you need input voltage/current and output voltage/current
Title: Re: You need at least 4 multimeters?
Post by: uwezi on March 04, 2014, 11:08:34 pm
Episode 110, let's design a SMPS @ 31:20

It was about the efficiency Dc/Dc converter, so you need input voltage/current and output voltage/current

And then you need a fifth one when you want to measure something which is inside the circuit, while still monitoring input and output. In other words, you cannot have too many multimeters - because then there is always number six, which is currently without battery...
Title: Re: You need at least 4 multimeters?
Post by: dr_p on March 04, 2014, 11:17:35 pm
And you have to like all of them, so you need at least 10 to choose the 6 from.
Title: Re: Re: You need at least 4 multimeters?
Post by: zapta on March 05, 2014, 02:32:54 am
And you have to like all of them, so you need at least 10 to choose the 6 from.

And then there are the cases when you work on two DC/DC at the same time...

I am getting alone with one.

Sent from my Nexus 5 using Tapatalk

Title: Re: You need at least 4 multimeters?
Post by: Pillager on March 05, 2014, 04:38:00 am
... In other words, you cannot have too many multimeters ...

Yes, you can. Fluke has so many they're selling them... ;D
Title: Re: You need at least 4 multimeters?
Post by: Fsck on March 05, 2014, 05:02:57 am
And you have to like all of them, so you need at least 10 to choose the 6 from.

occasionally, you might actually need/want all 10.
Title: Re: You need at least 4 multimeters?
Post by: Jon86 on March 05, 2014, 05:38:48 am
And you have to like all of them, so you need at least 10 to choose the 6 from.

occasionally, you might actually need/want all 10.

In what situation?
Title: Re: You need at least 4 multimeters?
Post by: robrenz on March 05, 2014, 05:42:43 am
For a post picture in show your multimeters  :-DD
Title: Re: You need at least 4 multimeters?
Post by: Dave Turner on March 05, 2014, 06:34:54 am
Don't forget the obligatory analogue meter(s).

I wouldn't be without my TMK 500, which is at least 30 years old, replacing another old trusty from the 60s (unfortunately accidentally destroyed by a friend  |O). Yes it has a 'burden' of 30k ohm/VDC, and requires careful thought before choosing the range and interpreting results.

Nevertheless analogue meters still have their place as discussed in another thread.
Title: Re: You need at least 4 multimeters?
Post by: Fsck on March 05, 2014, 07:24:07 am
And you have to like all of them, so you need at least 10 to choose the 6 from.

occasionally, you might actually need/want all 10.

In what situation?

some kind of electronic function test.
something with many sensors.
troubleshooting/analyzing a multiple channel power supply
there's a bunch of RF applications
characterizing a whole system for repeatability

the 3458a feels like the defacto physics research bench DMM. to save money, many labs combine it with a switch system to have multichannel capabilities. which gives you similar capabilities to multiple DMMs: I've seen this more often in SS&CM physics. on the other hand, I've also seen some labs equipped with half racks of 3458's and a high speed switch system for faster acquisition and higher accuracy or to ensure certain sets of measurements are done simultaneously: more common for particle physics.

addendum: need for 4 -> it's pretty common to want 2 voltage readings and 2 current readings simultaneously.
Title: You need at least 4 multimeters?
Post by: madshaman on March 05, 2014, 07:41:13 am
I don't understand how anyone can get by with just four DMMs :-)
Title: Re: You need at least 4 multimeters?
Post by: robrenz on March 05, 2014, 07:49:51 am
At least 2 of the 4 must have built in graphing :-+
Title: Re: You need at least 4 multimeters?
Post by: gdewitte on March 05, 2014, 08:05:03 am
You really need an odd number, so they can vote…
Title: Re: You need at least 4 multimeters?
Post by: sacherjj on March 05, 2014, 08:10:31 am
You really need an odd number, so they can vote…

If you have an even number voting, you can cast the last vote towards what direction you "need" the measurement to go. 
Title: Re: You need at least 4 multimeters?
Post by: Jon86 on March 05, 2014, 09:52:26 am
I wonder how big the largest collection of multimeters on here is...
Title: Re: You need at least 4 multimeters?
Post by: pickle9000 on March 05, 2014, 09:56:47 am
I wonder how big the largest collection of multimeters on here is...

Ask Dave.
Title: Re: You need at least 4 multimeters?
Post by: Astroplio on March 05, 2014, 10:29:12 am
You really need an odd number, so they can vote…

If you have an even number voting, you can cast the last vote towards what direction you "need" the measurement to go.

LOL you guys!
 
Title: Re: You need at least 4 multimeters?
Post by: babysitter on March 06, 2014, 07:24:38 am
I would say you need two DMM (for both labs), Computer control (GPIB) and a Multiplexer O0
Title: Re: You need at least 4 multimeters?
Post by: GiskardReventlov on March 06, 2014, 08:38:56 am
What's the handheld:bench ratio though?
Title: Re: You need at least 4 multimeters?
Post by: Dave on March 06, 2014, 01:12:50 pm
What's the handheld:bench ratio though?
4:7
Title: Re: You need at least 4 multimeters?
Post by: BMac on March 07, 2014, 12:04:47 am
Really, can you ever have enough test equipment, ooohh wait i see a new shiny piece of test equipment, gotta go!

BMac
Title: Re: You need at least 4 multimeters?
Post by: rjk5378 on March 07, 2014, 02:08:24 am
You also need experts on this forum and elsewher to opine often about the need for multiple multimeters and other types of equipment. This is useful when one needs to convince the bean counters at work or, as in my case, for the hobbiest to justify yet another expenditure to the spouse! And, in that regard, having lots of test gear on the bench makes it less obvious that I have smuggled in a new addition. I see each and every unit in all its beauty, but my wife just sees a bunch of junk! <g>
Title: Re: You need at least 4 multimeters?
Post by: GiskardReventlov on March 07, 2014, 10:15:12 am
having lots of test gear on the bench makes it less obvious that I have smuggled in a new addition. I see each and every unit in all its beauty, but my wife just sees a bunch of junk!

So true.  A variation on this theme is to maintain a certain level of messiness, it's easy to camouflage something new.  Don't leave the shipping carton laying around though.
Title: Re: You need at least 4 multimeters?
Post by: BravoV on March 07, 2014, 02:57:36 pm
Once you have graduated and have enough in the progress of collecting more and more DMMs  >:D, then don't forget the task on getting more ... <gulp> ... bench power supplies !!!  :-DD

Damn .. the curse never ends.  :palm:
Title: Re: You need at least 4 multimeters?
Post by: linux-works on March 16, 2014, 02:46:17 pm
another vote for some analog meters, too.

I am partial to the classic simpson 260.  not high Z, but just a classic that every EE should own.  when I see one hanging on someone's bench, I know they are fairly good at electronics ;)  (either that, or they're as old as the hills, lol)
Title: Re: You need at least 4 multimeters?
Post by: Rutger on March 18, 2014, 07:59:19 am
I don't want to brag, but I have 16 x Fluke 189 and 2 x Fluke 85V sitting on my bench. (The first lot I picked up at an auction and am sellling on ebay!).

I will probably end up with 2 of each kind. I love the 189 display and it isn't much larger than the 85V.

You can never have too many DMM's.   

:-DMM  :-DMM  :-DMM  :-DMM
Title: Re: You need at least 4 multimeters?
Post by: ErikTheNorwegian on March 18, 2014, 08:49:05 am
I got 3 Fluke 87V , 2 Flukev87V EX, 2 Fluke 8846A , 1 Fluke 8845A, 2 Fluke 123, 1 analog, 1 Keetly 2000, 1Fluke 115, pluss annother 5-10 diffrent ones in diffrent suitcases. Have a broken Fluke 123 in the post from ebay... so how many one needis realy a strange queastin, plenty pluss some more!
Title: Re: You need at least 4 multimeters?
Post by: Wim_L on March 22, 2014, 02:44:49 pm
A good reason to have some analog meters: if you sometimes need a lot of meters, but not often, an analog one will still work on volts/amps ranges without the batteries. So you can store them empty, without having to worry about batteries leaking after a while.

Assuming you can live with their lower input impedance, of course.
Title: Re: You need at least 4 multimeters?
Post by: zapta on March 28, 2014, 04:12:02 am
For a post picture in show your multimeters  :-DD

I see a big business opportunity here. Sell mock multimeters that look great in pictures you take. Will be a hit on Kickstarter.