The Multimeter

The Multimeter is an Electronics and General Electricity measuring device. All Multimeters will measure at least Voltage, Resistance, and Current- it is the perfect Ohm's Law measuring device.

A multimeter has three main parts:


The Display is where the value of your units is displayed. Be sure to pay attention to where the decimal point is on the number and match that up to the value of the unit you are measuring. 

Selection Knob

A typical Multimeter will have a radial dial Knob. Looking at the Knob, the Multimeter can measure Voltage (V), Current (A), and Ohms (Ω.) All Multimeters also measure something called "continuity" and that symbol is marked by a diode schematic or "wifi" symbol.


All Multimeters have at least three ports. These ports are COM, 10A, and mAVΩ. COM stands for Common at that is where the negative (black) probe always plugs into. The other two ports are for your positive probe (red) and which one you use depends on the total voltage and current you are testing. High Current only uses the 10A and low voltage, current, and resistance uses mAVΩ. This will have to be set on your Selection Knob as well.  


Banana Plug

Banana Plugs are used in many situations like the plugs that go into the ports of a multimeter or the ports of a DC Power Box or Oscilliscope.

Test Leads

Test leads allow for precision testing of small electronics and component leads. The downside of these is that you have to hold them while testing. 

Alligator Clips

These are great cables for connecting to large wires or pins on a breadboard. Good for performing longer-term tests where you don’t have to have to hold the probes in place while you manipulate a circuit. 

Reading Voltage

Use the V with a straight line to measure DC Voltage

Use the V with a wavy line to measure AC Voltage

To measure voltage, set your multimeter dial to a voltage value of the correct current that is higher than the anticipated measured voltage. For example, if you are measuring a power outlet at home in the United States, the voltage is 120V AC, so set your dial to 200V V~. 

Note: If you do not know the voltage, always start as high as possible and work down as to not break the multimeter. As you work down to smaller units, the meter will display a more accurate measurement. 

Reading Resistance

When resistance, you are measuring in Ohms (Ω.) For this, find the Ohm section on the dial. A good rule of thumb when measuring resistance is to always start higher than the component you're measuring. If you do not know the resistance of the component you are measuring, start at the highest value and work your way down. As you work down, you will get more accurate numbers from the display.

Knob set to 20 KΩ

Note how the Display is reading 0.46. This means it is 0.46 KΩ because the Knob is set to a high Kilo-unit.

Knob set to 2 KΩ

Note how the Display is reading 468 This means it is468 Ω because the Knob is set to the base Kilo-unit. As you get closer to the value, it becomes more accurate.

Knob set to 200 Ω

Note how the Display is reading 1. This means the value is higher than the base unit the knob is set to. In this example, we are measuring a 1 KΩ Resistor with a max measuring range of 200.

Reading Current

Reading current is one of the trickiest and most insightful readings in the world of embedded electronics. To measure current you have to physically interrupt the flow of current and put the meter in-line. This effectively “breaks” power to the circuit. We then insert the multimeter in-line so that it can measure the current as it “flows” through to the multimeter.

On the Current (A) section of the dial, you will see Amp values from 10A to 20uA. When measuring 10A, the Positive (Red) probe should be in the 10A, most left, port. All other currents can be read using the mAVΩ, most right, port. Just like when reading resistance, the display will show a number that must then be multiplied by its unit- A, mA, or uA. Pay attention to the decimal as well.