Make an LED Tester This Weekend
Warm up your soldering irons! This LED tester can be built in a weekend, but it will serve you well for years.
LEDs are one of the most basic components in an electronics hobbyist’s toolbox, but they can also be a little bit tricky to work with. If you have a pile of assorted LEDs without datasheets (who doesn’t?), how do you know what voltage you should drive them at? They vary widely, and if you give them too much juice, they are going to pop and never shine their beautiful, bright light again.
YouTuber Pro maker 101 came up with a nice, clean solution that anyone with a soldering iron and a handful of components could build in a weekend. Pro maker 101’s LED tester has a set of probes that can be touched to nearly any LED’s electrodes to not only verify that it works, but also reveal its operating voltage level.
The device is powered by a pair of 18650 Li-ion batteries connected to a 2S BMS for protection. An XL6009 boost converter does most of the work. In conjunction with a current-limiting resistor, the boost converter will provide exactly the level of voltage an LED requires, and no more. A digital voltmeter displays that voltage level, so you know how to drive it after you have finished testing it. Banana sockets allow probes to be attached to the device so that it is easy to make contact with an LED's electrodes.
To finish the LED tester off, the hardware was installed in a simple 3D-printed case. A switch was installed in the side of this case to shut the power off when it's not in use.
Pro maker 101 walks through the build process in just a few minutes. If you have the parts on hand, you should be able to make your own LED tester circuit nearly as fast. It’s a great tool to have on hand, so you can expect to get many years of use out of this little device.