the sorcery of copper

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I built two remotely controlled flashlight for a Halloween game.

For that I added a micro-controller in flashlights, which would receive the signal from an IR remote, and switch on/off the light (with a flickering fading pattern).


the circuit is really simple:

  • Unordered List Iteman infra-red demodulator (38 kHz, to be compatible with most remotes)
  • a transistor to power the light (nMOS)
  • a micro-controller to decode the IR command and switch the lights.

For the micro-controller I used an Atmel ATtiny85V. This can directly work with 2xAA batteries (2.0-3.0V) and 3xAAA (3.0-4.5V). Thanks to its small size it can be installed inside the flashlight.

1st prototype

this was more a proof of concept. it used an old incandescent-bulb-based flashlight. since the case is transparent, the IR receiver can also be placed inside.

2nd prototype

this uses a more robust flashlight in an aluminium case. the LED in the center has been replaced by the IR receiver.


two firmware versions have been writte:

  • the first to receive commands from more common remote controls using the IR NEC protocol
  • the second to receive commands from the more task appropriate Nikon shutter remote



to remotely control the flash light, I used a Nikon remote control. it was originally intended to trigger the shutter of some Nikon camera. but I re-used it because the form factor and single large button fitted my use case.

here are sigrok traces of the IR signal transmitted by the remote.

TV-B-Gone kit

to be sure the operator could remotely control the flashlight in all circunstances, I also provided a TV-B-Gone (Kit) re-programmed to only send the Nikon code (at very high power).

remote_flashlight.txt · Last modified: 2024/01/07 17:49 by