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Topic: Measure current ? (Read 936 times) previous topic - next topic

StenKrog

Hey Everybody

Can someone tell me the cheapest way to measure current. I need to measure up to 10A / 230VAC. ??

Maybe there is a link to a look-a-like project ??

retrolefty


Hey Everybody

Can someone tell me the cheapest way to measure current. I need to measure up to 10A / 230VAC. ??

Maybe there is a link to a look-a-like project ??


Well how about a digital multimeter rated to be able to measure up to 10 amps AC current? That is usually just at the limit of some meters and some are pretty inexpensive these days.

Lefty

jonisonvespaa

have a look on ebay for,

30A ACS712 Current Sensor Module 30 Amps

£3.50

BillO

A hall effect sensor would be my first choice.

A a few loops of wire around one of the current carrying conductors would be another, but you'd need to load it, rectify it and filter it so that you got an appropriate signal to feed to an MCU.
Facts just don't care if you ignore them.

jonisonvespaa

or this one
https://www.sparkfun.com/products/8883

cr0sh


Can someone tell me the cheapest way to measure current.


Cheapest way (ok, maybe not cheaper than inserting the multimeter directly in the circuit, using the 20A current measurement setting most meters come with)?

Homemade current shunt.

Basically, get a thick piece of solid copper wire of a known gauge that can handle your maximum current. Look up for the particular wire gauge what the resistance is per linear measurement. Measure out that much, then mount it using a couple of standoffs (copper bolts/nuts are best) to a non-conductive board (an small HDPE cutting board is perfect); you may have to coil or zig-zag it (don't let the coils touch each other!) to fit it in place. Hook your load up in series with it. Since you know the resistance of the length of wire, you know what it's voltage drop will be, and from that can calculate the current (Ohm's law, remember). Measure the voltage drop across the wire, and Bob's your uncle:

http://www.reuk.co.uk/Make-a-Shunt-Resistor.htm

More examples can be found online...

/note that this isn't as accurate as a -real- current shunt, due to heating and other enviromental factors over time, but it is much cheaper
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

kama1982

The best way to measure current is to use a wideband (including DC) current probe. If you don't have a current probe, then you need to insert a small resistor in the circuit to sense current. The resistor needs to be rated to handle the power, and it should be low enough that it doesn't effect the circuit much.

And you also find online stuff.

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