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DIY AC Ammeter from multimeter

A general cheap analog multimeter will not have directly AC current ranges.  But we are an Electric Appliance Repair, will always have this problem. For example: Measuring current of the electric appliances.

How to modify our meter?

How to use normal multimeter to measure high AC current

We can modify the multimeter on AC 10V range to measure AC current 0-10A, use a 1 ohms resistors in pallial to lead of meter.


The resistor must withstand power (watts) is adequate, do not burn while measuring.

How to find the power of resistors.
The current of the circuit squared then multiply by 2, to the safety of its use. The current value is about 2A is a resistor value that is equal to 8 watts (2x2x2).

Add to that the resistor will measure current less than 10A. Which is the highest on the scale? If you want to measure more than this to reduce the resistance to the other.

While the measure has to be careful not to resistors in parallel, then dropped it. Otherwise, the meter will be damaged

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This Post Has 9 Comments

  1. Thanks.

  2. hallo,

    danke für den tipp.muss manchmal den strom von waschmachinen messen…..

    viele grüße…..

  3. Hi,walter
    Thanks for your feedback.
    Please type in English because I am not understand you say.

  4. Would The Power Rating of the 1 ohm resistor be 100 watts?? P=IxE= 10A x10V=100watts and P=IxIxR=10x10x1=100watts??? Is This Right???use 1v scale Power would be 10 watts???

  5. @momename…..Thanks for the Tip//Sometimes I must measure the Electricity of the Washing machine.My German is Very Weak but I provided Everybody with a rough Translation..I know only about 300 words in German..Hope This Helps,,Bye For Now!!! PS* I Love This Sit…THANK YOU!!!!

  6. Hi, Mr OHM 1970.
    Thank a lot for your feedback.

  7. You can also rotate a bridge rectifier and place a DC current meter between the + and – output terminals of the bridge, and connect the AC input terminals in series to the load. Just make sure the start current of the appliance doesn’t greatly exceed the meter rating.

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