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An easy way to build an ammeter is buying a small voltmeter module with LCD, usually with 200 mV range.
To convert current to voltage you can use three different shunts
1 kΩ 1% -> 20 µA
1 Ω 1% -> 200 mA
0,51 Ω 1% -> 400 mA
If you need to be more accurate you can use a trimmer to adjust reading.
If 1 kΩ is too high you have to add an op amp amplifier to the circuit.
If you need an overload protection add two diodes and 1 resistor to the voltmeter input.
What i know is that in all ammeters a voltmeter is used. You can convert current to voltage using a resistor. Then use a A/D and a micro controller to get the value of the current.
The picture above is my voltmeter circuit. The value of R1 and R2 is 990kΩ and 9kΩ respectively. The ranges of my voltmeter are 200mV, 20V and 200V. When the input voltage is 200mV, use switch1. If 20V use switch2 and when 200V use switch3. All of these will have an output of 200mV which will then be amplified to 2.5V that will be connected to the ADC.
From the circuit above, how can I add my Ammeter circuit?
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