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[on:]

Here is a way how to measure a current on an ie. arduino system.
http://www.maxim-ic.com/datasheet/index.mvp/id/1853
Download pdf, and the figure 11. shows the current monitor schematics. It is a simple I->U converter.

[Reply #1 on:]

I am not sure to understand your question but if you want to measure a current with a voltmetrer (Arduino analog input are like a voltmeter) you can  use a transimpedance amplifier.
Search on google with this name there are many explanation and schematics.

[Reply #2 on:]

Basicly the Arduino A/D measures voltages.  So you need to run the current through a resistance, called a shunt, to generate a voltage.  Usually you want a very small resistance so you don't disrupt the current you are measuring.  This means you get a very small voltage, so you usually have to amplify it to get to voltages that an Arduino can accurately measure.

What type of currents do you want to measure?

[Reply #3 on:]

Hello!

I'm working into a project where  I need to measure the current, actually I'm using a multimeter to do it,
but I want to use arduino to improve the measures, so, How can I do it? I have a very basics knowledges in electronics
I designed and develop  a program that measure the voltage and storage into a data base, my program can display a graphics of this
but I really need to measure the current. In my laboratory we have some kind of bio-battery  that produce energy so I need to measure the current.
somebody can help me?

PD
Sorry for my english

Thanks for any help!

[Reply #4 on:]

Try using a current sensor instead. Very nice solutions include the S22P series from Tamura. They do most of the heavy lifting for you, i.e. the output signal is always positive, centered around 2.5V so the Arduino can read it no problem. Lesser solutions cost a lot less also, see the openenergymonitor project for guidance, theory, sensor selection, and the arduino code to remove a biasing signal.

[Reply #5 on:]

Thanks Constantine,

I'll read the information about openenergy.

I have one more question, in the next image


In this image we use a simple circuit and a protoboard with a variable resistor, we use a protoboard with a variable resistor, we use too three multimeters to measure
the current, voltage and resistence, so I was thinking, if I connect the wires to the multimeter to measure amperage to arduino, it will be possible to measure the current?, and if is possible, How I can  write this into the program for the arduino?.
The actual measures with the multimeters are for example, in current is around to 12 mA or 14 mA, in voltage is 750 mV.

[Reply #6 on:]

Hi again,

I forgot to mention that it is a DC power supply

[Reply #7 on:]

It would help to have a diagram of what you are measuring and where in the circuit. The picture is certainly nice to have, but the circuit is more important. Please include voltages being applied, resistances, etc.