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Project Notes

#446 RGB Joule Thief Night Light

Testing a slow-flash RGB LED with a 1.5V joule thief power supply.


Here’s a quick demo..



I recently got hold of some 5mm RGB Flashing LEDs from a seller on aliexpress - some slow and fast flashing varieties just out of curiosity. Here I’ve put one the slow-flash kind in a “night light” circuit.

I decided to power from a little 1.5V CR1216 coin cell. To boost the voltage sufficient to power the LED, I’ve attached a toroidal joule thief circuit, similar to LEAP#137 ToroidJouleThief.

The oscillating voltage produced by the joule thief is not suitable for the flashing LED as it is liable to get stuck on a single colour, so I’ve added a diode/capacitor charge pump to provide a more stable power source for the LED.


The circuit and breadboard equivalent are shown below, however for the actual construction I’ve gone a bit freeform including fashioning a battery holder from 0.9mm copper wire. The CR1216 battery slips in nicely (I haven’t added a power switch - the battery must be removed to turn it off).




Credits and References

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This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.