Multimeter Selection

[jamilm9]

be careful what you wish for. I just read this thread and i wish i had bought a better one and now my meters broken. :'(
sweet i'm elite 1337

 

[Kris.J]

I think we all got the picture.  However, some of us are not willing to spend the money on a Fluke if we're not likely to use it on a normal basis.

The same number of dollars can get you Fluke if you look hard enough.

Regarding measuring current, what I described is absolutely fundamentally true.  Sure there are exceptions - I've used a test load and measure voltage across a known resistance to calculate current via Ohm's Law in many different applications, especially when it is not convenient to get a meter connected in series - since before I knew this site existed.

In my opinion & experience with the electronics education system, fundamentals are learned first - then exceptions can be made.

You seem combative - perhaps you are, perhaps I just read it that way.  When it comes down to it though, I guess I couldn't care less.  I know what's right and proper in my world.  *shrug*

 

[Kris.J]

-You'll momentarily disconnect the circuit (because you're trying to hold the probes in place), charging up a capacitor, in which the eventual voltage spike when reconnected will damage sensitive electronics.

LOL! On a re-read, that one really made me laugh out loud.
Who the hell holds probes when doing a direct current measurement? ;D

 

[jamilm9]

i want
http://www.web-tronics.com/indmmwrspcin.html
but shipping is $30 to canada

 

[WonHungLow]

here is a decent meter from your local radioshack

http://www.radioshack.com/product/index.jsp?productId=2103962

it is normally 90.00 but they have it on sale for 49.00

 

[phoenix3200]

The same number of dollars can get you Fluke if you look hard enough.

When a fuse set for a Fluke costs just as much as a cheap but function-filled multimeter, I would tend to disagree. Meters like this, which is just about the cheapest Fluke you can get on eBay don't have near the functionality of what I was looking for (or got). To get one that measured temperature (which was a must for me) would have cost me $100, when I could have found a knock-off with very similar features for $30 or less.

Regarding measuring current, what I described is absolutely fundamentally true. Sure there are exceptions - I've used a test load and measure voltage across a known resistance to calculate current via Ohm's Law in many different applications, especially when it is not convenient to get a meter connected in series - since before I knew this site existed.

The multimeter measures current in exactly the same manner: it calculates the voltage drop across a known resistance. At the voltage values we are playing with, such a measurement is likely to skew your results. Measuring a voltage drop across an established resistance will set our multimeter in a high-impedance mode, thereby minimizing the side-effects on the circuit.

In my opinion & experience with the electronics education system, fundamentals are learned first - then exceptions can be made.

I hope this wasn't a lame attempt at trying to brand me as another fifteen year old. I taught a laboratory course regarding silicon devices at a Big Ten university to Engineering undergrads last year. Edit: We also spend the first three weeks instructing them to do INDIRECT current measurement rather than direct current measurement.

You seem combative - perhaps you are, perhaps I just read it that way.

One would tend to be after seeing a newcomer try to smear people he has no knowledge about for the second time. You have not given a logical explanation for why a hobbyist should care about owning a Fluke or not; all you've done is say that you like them. Do you think it will matter to them if the adjustment is off by 2% over the course of five years? Most electronics components don't even have such a good tolerance.

When it comes down to it though, I guess I couldn't care less. I know what's right and proper in my world. *shrug*

It's nice to know that you care so little that you changed your custom text to Fluke, even your Mom knows. It's also nice to know that you've given up on learning, which is the primary purpose of forums.

Who the hell holds probes when doing a direct current measurement? ;D

They've been putting the current measurement setting on plenty of meters that have integrated probe cords, which is what most LPF users are likely to have. Many of the users have also not even taken your "fundamental electronics course", so they would be very likely to do the above, damaging sensitive electronics in the process.

 

[phoenix3200]

i want
http://www.web-tronics.com/indmmwrspcin.html
but shipping is $30 to canada

Check what shipping a package from US zip code 47909 to you would be. If it's less than $18, just PayPal me $42 (it costs $12 for shipping to me ) plus the correct amount to Canada, and I'll forward it to you. I'm interested in getting their free offer DMM so that I could dedicate one to temperature measurements, but I did not notice it until the order went through.

Edit: Dang, the RadioShack multimeter really isn't that bad!

 

[Benm]

Holding the probes while measuring current isnt fundamentally bad, as long as you know what you are doing. One thing i commonly do when measuring current consumption of battery powered devices is removing the switch/tailcap and complete the circuit with the meter in 10A mode.

This is fine, your intermettent probe contact on placement is just as bad as the bounce from the switch can be and your device should be okay.

As for soldering in a shunt to measure current: That's all good, but choose the shunt properly. I commonly use 1 ohm resistors, but those DO drop a mV for each mA, which ends up a few 100 mV for typical red lasers. If fed from batteries, the circuit must have enough voltage to work with to overcome this. A 0.1 ohm resistor might be better, but those are not commonly available in the typical E12/E24 series vendors carry.

 

[jamilm9]

[quote author=jamilm9 link=1227395212/0#19 date=1228782920]i want
http://www.web-tronics.com/indmmwrspcin.html
but shipping is $30 to canada

Check what shipping a package from US zip code 47909 to you would be.  If it's less than $18, just PayPal me $42 (it costs $12 for shipping to me ) plus the correct amount to Canada, and I'll forward it to you.  I'm interested in getting their free offer DMM so that I could dedicate one to temperature measurements, but I did not notice it until the order went through.

Edit: Dang, the RadioShack multimeter really isn't that bad![/quote]
well i don't know the weight

 

[pseudolobster]

I recently bought this multimeter: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=270298327902 ... A "Wavetek 15xl", and I'm happy with it so far.. It has a 1kv range and a 10A range, plus an audible continuity tester, which is all I was really looking for... I got shafted on the shipping to canada, the guy charged me $25.60 when the shipping really only cost $3.95, but still it's a decent little meter...

Looks like the one phoenix3200 posted is overall better, in that it measures capacitance and temperature.. Though mine has a "20MHz Logic Testing" feature which appears to be pretty much useless, and is basically saying "while I can't count frequencies, I can sample voltages really fast in case you care"... Looks to be lower build quality though.

In short, Wavetek apparently makes cheap high quality meters (I'm pretty sure they're actually a subsidiary of fluke), and you might be able to find some on eBay..

[edit]After re-reading the OP, I realize you're looking specifically for capacitance measurement and a thermocouple... the "16xl" has a frequency counter, capacitance measurement, and a hold button, but afaik no thermal... I'm not really sure they make one with a thermocouple, so my advice is moot. :-/[/edit]

 

[phoenix3200]

well i don't know the weight

3.0 lbs according to UPS. I'll have to guess on the box size this evening.

 

[jamilm9]

what this look like
http://cgi.ebay.com/Digital-Multime...286.c0.m14&_trkparms=66:2|65:15|39:1|240:1318

 

[Kage]

[quote author=Kris.J link=1227395212/0#3 date=1228517414]You can't go wrong with Fluke

I've got one of those - a Fluke Model 79 Series II

That's 15 bucks that I think is better spent on a used Fluke off eBay.

I think we all got the picture. However, some of us are not willing to spend the money on a Fluke if we're not likely to use it on a normal basis.

Is this a good meter?
http://www.dealextreme.com/details.dx/sku.10018

If you just need a meter for simple DC/Resistance measurements, that's more than adequate.

What setting do you need to put it on to read how much current is coming from the driver? (I know you need a testload : )

When measuring current, the meter is connected in series with your circuit - the meter actually completes the circuit.

NO. ABSOLUTELY NOT. While this may be the "proper" way to measure current, DO NOT do this!!! Do NOT use the current setting on your meter for sensitive electronics. A number of things will occur, including, but not limited to:
-You'll add an unintended resistance/capacitance load to your circuit, which will affect the test load/your driver's operation.
-You'll momentarily disconnect the circuit (because you're trying to hold the probes in place), charging up a capacitor, in which the eventual voltage spike when reconnected will damage sensitive electronics.

The second one is key, and is the main reason why diodes get blown. The driver itself will also not appreciate an infinite resistance load.

INSTEAD, you should get the common test load shown around here, or build your own: 6x 1N400x diodes, and 1x 1 ohm resistor, all in series. If you take your multimeter and measure the DC voltage drop across the 1 ohm resistor, the voltage shown on your meter = the net amount of current flowing thru the circuit. Since a multimeter is usually 1 M Ohm when it's in the DC measurement mode, you won't affect the circuit.

The ONLY location in the circuit which is acceptable to use the current measurement is between the battery and the driver - but unless you're using a linear drop out driver like the DDL, this will not equal the current that your diode will recieve![/quote]

Damn right! You may get away with it once or twice, but sooner or later your diode will end up fried! I have some fried ones for sale, very cheap...

 

[kristopher]

I just recently was looking for a good, cheap multimeter.  Flukes are grand, but they are way overpriced.  I needed to measure dc microamps and have a rs232 output.  

This is what I found: http://www.emovendo.net/magnet/multimeter-digital-with-rs232-computer-interface.html

$33+ shipping.  I don't understand counting functions. List what you really need and make sure it has it.  This one does temperature, though.

The computer connection is typical, but it works.
EDIT: it is also 10A fused. Most aren't at 10A.
I have a 10% off coupon if anyone wants it.  PM me.

 

[phoenix3200]

Damn right!  You may get away with it once or twice, but sooner or later your diode will end up fried!  I have some fried ones for sale, very cheap...

When I read that I thought...you can only look into a laser twice...

This is what I found: http://www.emovendo.net/magnet/multimeter-digital-with-rs232-computer-interface.html

Not bad!  You just sent me into "Buyer's Regret" mode...

My meter is fused for both 10A and 400mA, and has a bar graph, but otherwise, the meter you have can do the capacitance range I wanted (and can use the probes) and its got a frequency counter!  Oh well...

Jamlim, check what shipping would be on the meter kristopher found would be to you.  If you would prefer, I'll box my meter back up and ship it off to you for less than retail - plus I won't charge you so much for shipping.

Edit: Thx for the rep! Someone had to set him in his place.

 

[jamilm9]

no i just bought one locally like the on ebay i showed.