How to use a multimeter for measuring a current???

hello guys, how are you??
Recently i ordered this multimeter from DX
http://www.dealextreme.com/details.dx/sku.9636
because i need to set a current for my Lavadrive V3.. of course in a future i would like to build my own DDL driver and i will need those knowledges as well..
I havent recieved multimeter yet but  i want to be prepared for wokr with my first ONE..  
I have a couple of questions about this device as i have never used it before and i found on the DX site between customers feedback that this multimeter comes with chinese manual, which means that i will be probably unable to learn how it works by myself. :-/

Could anyone please described what does marked points 1-6 on my picture means??? what can i measure in each position?? what for is each position?
On the other hand everything i will need to know for now is
HOW TO MEASURE A CURRENT [ch8211] which position i must to set for measuring a current...

thanx in advance

Re: How to use a multimeter for measuring a curren

one more question..

i was watching couple of videos around the youtube how to measure a current and there was described that i need to connect a multimeter

IN SERIES with circuit...

on the other hand i found this schema on the forum -see picture 1- where you measure a current across the resistor..

so i drew my idea how to measure a current by following advice from youtube - picture 2-...

which one is right?? i am little bit comfused...

Re: How to use a multimeter for measuring a curren

You need to do some more research and reading on the existing posts...

It has been stated a hundred times if not more on the Posts on this Forum...
what the safest way to measure the current of your driver's output is....

You need to do some reading... :'(

It is all there.... that is where I found  the info....

BTW... I'll believe what is posted on this forum.... way before I believe what
I see on YouTube...

Jerry

Re: How to use a multimeter for measuring a curren

MilanTheOne said:

one more question..

i was watching couple of videos around the youtube how to measure a current and there was described that i need to connect a multimeter

IN SERIES with circuit...

on the other hand i found this schema on the forum -see picture 1- where you measure a current across the resistor..

so i drew my idea how to measure a current by following advice from youtube - picture 2-...

which one is right?? i am little bit comfused...

Click to expand...

Both are correct. If you're going to use option 1, then you need to measure the voltage across the resistor. Voltage on your multimeter is either position 1 or 2, I am not sure which, but one of the options measures voltage in alternating current, and the other option measures voltage in direct current. We want to measure in direct current.
If you're going to use option 2, then set the multimeter to position 6 to measure the aperage going to the diode.

Re: How to use a multimeter for measuring a curren

lasersbee said:

You need to do some more research and reading on the existing posts...

It has been stated a hundred times if not more on the Posts on this Forum...
what the safest way to measure the current of your driver's output is....

You need to do some reading... :'(

It is all there.... that is where I found  the info....

BTW... I'll believe what is posted on this forum.... way before I believe what
I see on YouTube...

Jerry

Click to expand...

well i have done a lots of reading around the forum but i have a specific question about multimeter which i purchased... in my second question i need only answer which of those two case is right.. i suppose that those first one which i found on the forum, but could anyone explain why???

Re: How to use a multimeter for measuring a curren

Jimmymcjimthejim said:

[quote author=MilanTheOne link=1232904347/0#1 date=1232904867]one more question..

i was watching couple of videos around the youtube how to measure a current and there was described that i need to connect a multimeter

IN SERIES with circuit...

on the other hand i found this schema on the forum -see picture 1- where you measure a current across the resistor..

so i drew my idea how to measure a current by following advice from youtube - picture 2-...

which one is right?? i am little bit comfused...

Click to expand...

Both are correct. If you're going to use option 1, then you need to measure the voltage across the resistor. Voltage on your multimeter is either position 1 or 2, I am not sure which, but one of the options measures voltage in alternating current, and the other option measures voltage in direct current. We want to measure in direct current.
If you're going to use option 2, then set the multimeter to position 6 to measure the aperage going to the diode.[/quote]

so it is possible to measure a current without connecting a multimeter in series, right... like on the first picture..
it is far easier, isnt it??

Re: How to use a multimeter for measuring a curren

People say that option 1 for measuring current is far more accurate, but I have yet to experience this. Whatever one is easier is your preference

Re: How to use a multimeter for measuring a curren

Jimmymcjimthejim said:

People say that option 1 for measuring current is far more accurate, but I have yet to experience this. Whatever one is easier is your preference

Click to expand...

thank you very much that is exactly th ANSWER i was expecting when i posted my question.. simple and helpfull..

but my first question about MY KIND OF MULTIMETER still remains.. i will appreciate every suggestion

cheers

Re: How to use a multimeter for measuring a curren

Option one is safer, you can connect and disconnect your meter any time you like and you will not kill the LD.....which you may do if the meter is part of the circuit and you forget to discharge the capacitor.

BTW... I'll believe what is posted on this forum.... way before I believe what  
I see on YouTube...

Click to expand...

I couldn't agree more.

Meter settings
1) AC (mains stuff)
2) DC volts (our stuff, including measuring ma from driver through the 1ohm resistor)
3) Resistance
4) Checks continuity of circuit and can check LD's (connecting to the + - pins, one way will show zeros, the other way will display around 1.4, means LD is probably OK)
5) & 6) Amps @ different amplitudes :, ( I tend to leave this section alone)

Regards rog8811

Re: How to use a multimeter for measuring a curren

I read somewhere long ago that it was not possible, but  you can also measure the current simply by placing the test leads straight across the output of the driver with no load.

This is a very bad idea if your measuring anything other than a LMXXX, like a lavadrive or any boost that needs a load.

OR

If you need to measure say 400mA and the meter can only do up to 200mA, than using the 1 ohm resistor is the better bet.

I would like my spoon back now... :

Re: How to use a multimeter for measuring a curren

MilanTheOne said:

[quote author=lasersbee link=1232904347/0#2 date=1232905371]You need to do some more research and reading on the existing posts...

It has been stated a hundred times if not more on the Posts on this Forum...
what the safest way to measure the current of your driver's output is....

You need to do some reading... :'(

It is all there.... that is where I found  the info....

BTW... I'll believe what is posted on this forum.... way before I believe what
I see on YouTube...

Jerry

Click to expand...

well i have done a lots of reading around the forum but i have a specific question about multimeter which i purchased... in my second question i need only answer which of those two case is right.. i suppose that those first one which i found on the forum, but could anyone explain why???
[/quote]

I responded to your 2nd question on how to measure current of your driver's output...
No offence.... but the response was valid...

Your question is NOT a new one.... :-?

Too many times... new members ask the same questions that have been answered
in the Forum an "umpteen" number of times before... merely because they don't want
to spend the time and effort to do their own research (on this free forum)... or are too
lazy and want to be "Spoon Fed" all the answers.... :-/

Jerry

Re: How to use a multimeter for measuring a curren

Option one is safer, you can connect and disconnect your meter any time you like and you will not kill the LD.....which you may do if the meter is part of the circuit and you forget to discharge the capacitor.

Click to expand...

I just quoted myself louder as I think this is the important point, it is so easy to do the safest thing why pee about with a way that is fraught with danger?

Regards rog8811

[edit] first post here, case in point  http://www.laserpointerforums.com/forums/YaBB.pl?num=1232841355/0#0[/edit]

Re: How to use a multimeter for measuring a curren

As I already posted in another thread....

Using your DMM set to read amperage... and putting it in series with the load (assuming you're
measuring the actual LD's current) is risky... because as we all know... intermittent connections
can blow the Laser Diode... and putting the meter in series you will probably use alligator clips
to make the connections (not a solid connection) that could slip loose..(that is 4 possibly connections
that could come loose or be intermittent)..
Not to mention the 2 test leads plugged into the meter (if not 100% tight) may also be a point
of intermittent connection.. that makes 6 possible intermittent connections... :-?

IMO... It is obvious which is the better method.... unless you like buying LDs on a regular basis..

Who would like the Spoon next... :

Jerry  

Re: How to use a multimeter for measuring a curren

rog8811 said:

Option one is safer, you can connect and disconnect your meter any time you like and you will not kill the LD.....which you may do if the meter is part of the circuit and you forget to discharge the capacitor.

Click to expand...

I just quoted myself louder as I think this is the impoertant point, it is so easy to do the safest thing why pee about with a way that is fraught with danger?

Regards rog8811

[edit] first post here, case in point  http://www.laserpointerforums.com/forums/YaBB.pl?num=1232841355/0#0[/edit]

Click to expand...

I use the 1ohm resistor when testing diodes, and have to just monitor the mA while going through a few of them. When I setup the etched boards and have 20 in front of me, I use the meter straight across the output to check that the boards are good and are putting out the expected current.

A 1ohm in series with the load is much safer if you are still new to things and dont want to take any chances. But only seems to be important if the diode is hooked up while testing. I no longer find myself testing any boards with an LD, but rather a test load if any. I have noticed though, that using the 1ohm will drop the mW output by a few digits, and that value will change when its removed.

I guess its dependant on the individuals needs and what works better for ones purpose.

Re: How to use a multimeter for measuring a curren

this reminds me of another thread, also about the ddl driver. ended in him flaming me via pm...

//edit: please ignore, got that messed up.

Re: How to use a multimeter for measuring a curren

rog8811 said:

Option one is safer, you can connect and disconnect your meter any time you like and you will not kill the LD.....which you may do if the meter is part of the circuit and you forget to discharge the capacitor.

BTW... I'll believe what is posted on this forum.... way before I believe what  
I see on YouTube...

Click to expand...

I couldn't agree more.

Meter settings
1) AC (mains stuff)
2) DC volts (our stuff, including measuring ma from driver through the 1ohm resistor)
3) Resistance
4) Checks continuity of circuit and can check LD's (connecting to the + - pins, one way will show zeros, the other way will display around 1.4, means LD is probably OK)
5) & 6) Amps @ different amplitudes :, ( I tend to leave this section alone)

Regards rog8811

Click to expand...

Thank you Rog..
Great answer as always..    

you are THE ONE for me

lasersbee said:

[quote author=MilanTheOne link=1232904347/0#4 date=1232905785][quote author=lasersbee link=1232904347/0#2 date=1232905371]You need to do some more research and reading on the existing posts...

It has been stated a hundred times if not more on the Posts on this Forum...
what the safest way to measure the current of your driver's output is....

You need to do some reading... :'(

It is all there.... that is where I found  the info....

BTW... I'll believe what is posted on this forum.... way before I believe what
I see on YouTube...

Jerry

Click to expand...

well i have done a lots of reading around the forum but i have a specific question about multimeter which i purchased... in my second question i need only answer which of those two case is right.. i suppose that those first one which i found on the forum, but could anyone explain why???
[/quote]

I responded to your 2nd question on how to measure current of your driver's output...
No offence.... but the response was valid...

Your question is NOT a new one.... :-?

Too many times... new members ask the same questions that have been answered
in the Forum an "umpteen" number of times before... merely because they don't want
to spend the time and effort to do their own research (on this free forum)... or are too
lazy and want to be "Spoon Fed" all the answers.... :-/

Jerry
[/quote]


well i must to tell you that it is not my case... i am not a brand new here as you can see by my posts..
i did ask because i didnt find an answer selfhelp.. you shoud see that i have spent some time to find answer by myself as i have seen a lots of videos and checked a lot of stuff around the forum and Wiki..
i am sure that answer could be here on the forum because since i am here and i regularly check a lots of stuff in each section i can see that lots of new questions are actually answered and that  new members have same questions all the time, but i really didnt find an answer [ch8211] probably i didnt check on right places..   :-/
no offence  - peace on you, but in this case my question was valid as well..  :

lasersbee said:

As I already posted in another thread....

Using your DMM set to read amperage... and putting it in series with the load (assuming you're
measuring the actual LD's current) is risky... because as we all know... intermittent connections
can blow the Laser Diode... and putting the meter in series you will probably use alligator clips
to make the connections (not a solid connection) that could slip loose..(that is 4 possibly connections
that could come loose or be intermittent)..
Not to mention the 2 test leads plugged into the meter (if not 100% tight) may also be a point
of intermittent connection.. that makes 6 possible intermittent connections... :-?

IMO... It is obvious which is the better method.... unless you like buying LDs on a regular basis..

Who would like the Spoon next... :

Jerry  

Click to expand...

Thank you for this answer  

kendon said:

this reminds me of another thread, also about the ddl driver. ended in him flaming me via pm...

Click to expand...

i dont know if you are talking about me or about a LASERSBEE, as i have never sent you a PM  




anyway thank you guys, now i just need to study what does each position exactly mean and what for it is..

thanx