A multimeter is an electronic hobbyist's best friend, as it can measure voltage, resistance and current continuity. Whether troubleshooting malfunctioning electronics, building circuit boards or testing batteries, a multimeter will provide you with instant information about the electricity passing through your circuit and help you fix or improve it. Most multimeter devices have a measurement dial or knob, two probes and three jacks -- common, mAVΩ and amperage. Depending on how much you want to spend or how much precision you need, multimeter prices range from $10 to hundreds of dollars.
Plug the black probe into the common jack (COM) and the red probe into the mAVΩ jack.
Adjust your knob or dial to an appropriate voltage range, depending on the type of multimeter you have and what you are measuring. For battery or circuit-board testing, select the voltage (indicated by a number and the letter V) closest to the highest capacity of the battery or other power supply. For example, if measuring a 9-volt battery, turn the dial to 10V or higher if necessary.
Press the red probe to the positive end of your battery or power source and the black probe to the negative. For a bread or circuity board, simply insert the probes at connection spots with exposed wire, connecting the red probe to a red wire and the black probe to a black one.
Read the result. If no number appears or a strange symbol is displayed, you need to readjust your voltage knob to a better range. For more decimal places, you may need to lower your voltage setting to get closer to the actual number.
Turn your settings knob to an appropriate ohm (Ω) range for the circuit, resistor or transistor you are measuring. Resistors and other circuitry are color-coded, but if you do not have a chart, it's good to start at roughly 20kΩ and work from there. Your probes should be in the same jacks you use to measure voltage.
Touch the probes to the lead wires or cables on either side of the resistor or other device you wish to measure.
Change your resistance settings on the main knob if you are getting no or strange results. Ohm setting come in just Ω and kΩ, which represents 1,000 ohms, so be careful not to keep under- or overshooting the resistance range.
Adjust your multimeter to current measurement setting. Most consumer-grade multimeters have a setting on the dial or a button that is a dot with two or three short, curved lines next to it like a sound wave.
Turn off the power supply of the device you are measuring, as measuring the current continuity does not require power.
Touch the red and black probes to opposite ends of the circuit, breadboard or device in order to measure the current passing through the system. Current is also called amperage and is measured in amps (A), milliamps (mA) and microamps (μA).
Turn off your multimeter when not in use to save the battery.
If you keep getting negative results, switch your red and black probe wires.