It's widely known among EEs. It's used for lots of interesting things, such as temperature control, motor control and positioning, and LED lighting. You can do

It's widely known among EEs. It's used for lots of interesting things, such as temperature control, motor control and positioning, and LED lighting. You can do it in hardware old-style with a 555 timer or hex inverter, but most modern systems I've worked with do it with a microcontroller. An addendum to this that you may find interesting -- I've experimented with turning the LED on for a few microseconds at higher than rated current, then off for tens of milliseconds. The average current stays far below the specifications. This results in very high apparent brightness per unit of power consumption. Using the IV curve of the LED, this also let me eliminate the typical current-limiting resistor. The power savings are more than the power cost of the MCU that controls it (modern low-power microcontrollers are awesome). Anyway, the end result is a little LED + CR2032 cell + magnet that you stick to furniture, and it runs for about 3 years. I made it so that elderly people I know who wake up at night to go to the bathroom don't bump into furniture (especially in an unfamiliar place, like while traveling). Without creating a thing they have to think about often. If you're curious, I posted the code here: https://github.com/seanboyce/tinylight https://github.com/seanboyce/tinylight An additional one you might like: I did PWM for LED dimming in the tens of Mhz for some 1 Watt red LEDs. This is for my wife -- when she has a migraine she prefers very dim red light to complete darkness. In the Mhz range, there's no visible flicker by a longshot (although it costs a little more power). Most PWM systems I've seen that flicker, use lower-frequency signals. It must have been cool to play with LEDs in the 70s. We sort of take them for granted now, but they are so awesome. Truly we live in an age of wonders.