Your Multimeter
2. Setting the Stage
Alright, grab your multimeter. Don’t worry if it’s been gathering dust in the garage; it’s about to have its moment in the spotlight. First things first: we need to set the multimeter to the “diode test” setting. This is usually represented by a diode symbol, which looks like a triangle pointing to a vertical line. If your multimeter doesn’t have a dedicated diode test, you can sometimes use a low voltage resistance setting, but the diode test is generally the preferred and most reliable method. If your multimeter has an audible beep, set it to continuity checking mode.
Make sure the probes are plugged into the correct jacks on your multimeter. Typically, the black probe goes into the jack labeled “COM” (for common or ground), and the red probe goes into the jack labeled “VmA” (for voltage, ohms, and milliamps). Double-check this because having the probes in the wrong jacks can lead to inaccurate readings or even damage to your multimeter (though that’s rare with modern multimeters). You’ll want to avoid touching the metallic tips while testing, hold by the insulated areas of the test leads.
Before you even touch the LED, give your multimeter a quick sanity check. With the probes not touching anything, the display should show “OL” (for overload) or some other indication that the circuit is open. Now, touch the probes together. The display should drop to near zero, indicating a closed circuit. If your multimeter beeps, that means it’s detecting continuity. This confirms that your multimeter is working correctly and ready to sniff out some LED polarity.
Remember, safety first! While working with low-voltage LEDs and a multimeter is generally safe, it’s always a good idea to exercise caution. Avoid working in wet or damp environments, and if you’re unsure about anything, consult the multimeter’s manual or a knowledgeable friend. Now, let’s get those LEDs glowing!