The idea for AddOhms #8 has been around for quite some time.  I’m always trying to find ways to explain why current limiting resistors are necessary.  So while working in the shop one day, I decided to play with some LEDs and a bench-power supply.  Then I decided to record what happens.


In fact, I shot all the lab video used here one day.  Then about 3 weeks later, I got around to writing the script for this tutorial.   Since the two were disconnected, you’ll probably notice a couple of jump cuts in the live action footage.


Fan of making things beep, blink and fly. Created AddOhms. Stream on Twitch. Video Host on element14 Presents and writing for Hackster.IO. Call sign KN6FGY.


  1. Love your site and videos! Great Job… I enjoy LEDs and have used pre designed LED strips, lights, etc for some time. I found a particular wavelength LED I want to use and find I am burning them out! most likely due to direct battery connection and over current supply to the LED, so your video is very helpful…BUT, I recall somewhere on your sites you described most LEDs are designed to operate up to 2 volts above the ‘vf??? That didn’t seem right to me but I set up some lights designed for Vf of 1.9-2.3 on AA batts, running about 2.7 volts and thought that would be ok…funny thing very bright!! and lasted about 5 hours…so your current explanation must the the cause. But how do small LED flashlights I see and have taken apart have AA or AAA batts driving LEDs, but with no resistors?? That’s my question…Thanks for your site…

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