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Project Notes

#732 LED Flicker Kit

A flame or fire emulator driven by an ATtiny85 suitable for use in scale models or displays.



It is quite common that I’ll want to add fire or flame effects to a scale model build. This project is a general-purpose solution that could be installed to provide a range of effects from a raging billowing fire through to gently glowing embers.

I have tried various ways to mimic fire, but one of the most reliable is the one used here: a simple algorithm implemented in a microcontroller (an ATtiny85 in this case).

Circuit Design

The controller is implemented in code on an ATtiny85. Some circuit notes:

  • the PWM outputs are used to control low-side n-channel FETs rather than directly drive the outputs. This ensures that current load on the ATtiny85 does not exceed limits (10mA per pin, 60mA total).
  • the LEDs and accompanying current-limiting resistors are just for demonstration purposes - these can be changed as required for a particular application.
  • the flame animation aggressiveness is set with a variable resistor.
  • I initially built this to be run from 5V USB but got stumped trying to hide a suitable power supply in the picture frame. Luckily, the circuit also works just fin on 3V (2xAAA) - though I don’t know how long the batteries will last.



Testing on a breadboard:



The code is available in GitHub. It comprises:

Protoboard Build

After breadboard verification, I put the circuit on a small protoboard. I’ve given this one to a fellow modeller.


Credits and References

Project Source on GitHub Project Gallery Return to the LEAP Catalog

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.