#2 UNBasics: How to measure current without an ammeter.
If you don't have an ammeter or a multimeter with amp measurement, you can use a regular voltmeter or an oscilloscope to measure the voltage across a known value resistor.
Measure the voltage, divide the voltage by the resistance to get the current.
Ohm's law: V=I*R (or I = V/R).
Note about the resistor: while the colour-coding is easy to read, it's not accurate. The resistor's nominal value is 620Ω, but it has a 5% tolerance, so its actual value can be as high as ~650Ω or as low as ~590Ω. For accurate calculations, it's important to know the exact value.
The SHUNT video to which I made a reference: • How to Make a Shunt Current Sense Resistor
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