Help me chose an ampere meter for mesuring in the range 0-12V & 0-10A

[kjemmo]

Hi

This is my first post.

I am new to DIY electronics and need to learn a lot. I hope that you will all be kind enough to answer some newbie questions.

I am currently playing around with some solar cells and TEG projects for charging my iPhone when I go hiking.

I have a very basic multimeter that can measure voltage, but I need an ampere meter that can give me current measurements with a least 10ma accuracy.

I bought a cheap clamp ampere meter on ebay.com but it seems that it can not measure the low current and voltage that I am playing with.

The specs are as follows:

Range AC20A Resolution 10mA Accuracy ?2.5%+10d)
Range AC200A Resolution 100MA Accuracy ?2.5%+10d)
Range AC600A Resolution 1A Accuracy ?2.5%+10d)

Question #1:
Do I need to find a clamp ampere meter with a lower range like: Range AC2A Resolution 1mA Accuracy

Question #2:
Should I look for a different type of meter like this one: **broken link removed**?

Question #3:
Or are there better options that do not even know about?

The lowest voltage and current I will need to measure will be ~0.5V & 100ma.

All suggestions are most welcome.

Thanks

 

[RCinFLA]

There two basic ways to measure current. By voltage drop across resistance and by measuring magnetic field created by current passing through wire.

Hall effect sensor can be bought that give pretty good resolution. Look for closed loop hall effect sensor for best accuracy. They have an amplifier that drives the magnet field to near zero in the sensor core to reduce the non-linear magnetic properties of core material.

For measuring with shunt resistance start will most sensitive volt meter. 200 mVdc digital module are very inexpensive. You can buy high stablity shunt resistor or fabricate a low resistance shunt by using copper wire. I once made a 50 amp shunt from #12 solid copper house wire. Its accuracy was not bad just by calculating the lenght of wire from charts published on ohms per 1000 feet for various wire types. If you have another calibration reference you can find tune its length in the shunt. Copper wire has some relatively small temp coefficient.