Picture of Geiger counter triggered LED decorations

Bored of blinky lights that blink in response to time?
Make them blink with space instead!

This instructable shows a quick method for connecting LED tree decorations to a Geiger counter via arduino, so that the lights blink between different strings each time radiation is detected.

It's nicer to think of this as "cosmic rays" than some of the other possibilities...

What you'll need:
  • A Geiger counter with pulse output (I'm using the Gieger counter from MightyOhm)
  • A few strings of battery-operated LED decorations (I'm using stars and snowflake decorations from Poundland, 'cos you gotta love dem luminous spheres of plasma and dem frozen supercooled cloud droplets)
  • Arduino-based microcontroller (either a proper development board, or I'm using a stripboard bare bones version)
  • Female header (two or three sockets' worth)
  • Batteries/alternative power supply for your Geiger counter and Arduino
  • Assortment of connecting wires (either jumper leads or multi-core stuff to solder)
  • Soldering equipment, wire cutters, wire strippers etc.
  • Maybe a spare LED for testing, insulation tape...

Step 1: The Geiger counter

Picture of The Geiger counter
The Geiger counter from MightyOhm includes a pulse output :

The PULSE connector (J6) has the following pinout:

1. VCC (nominally 3V)

2. pulse output – a short (100us) active high pulse every time the geiger tube fires

3. GND


Geiger counter triggered decorations

We need to connect the GND pin (the one on the right) with a ground pin on our arduino and the pulse output (middle) with a pin on the arduino so we can detect the detections.

Cut 3 sockets' worth of female header. (You can get away with two if you have to.)

Cut yourself two lengths of wire long enough to reach between your Geiger counter and your arduino. It's helpful to have two different colours, but not essential. I'm something of a traditionalist and have used black for ground and red for the pulse output...

Solder the ground wire to one of the outer pins and the pulse wire to the middle pin.

This assembly should fit nicely onto the male pins on the Geiger counter:

Geiger counter triggered decorations
13thvulture3 years ago
just don't give a anyone an atomic warhead or a cellphone for christmas if they have this, it will ruin the surprise.
Silence3 years ago
So the faster the lights blink, the more you should be worried about whats under the tree :P
Christmas at ground Zero
PS118 beat me to it, but the video isn't available in my country :P
I wouldn't be so worried about who got there first. If all the lights appear to be on at the same time, move house--VERY QUICKLY.
PS1183 years ago
Finally! The perfect decoration for "Christmas at Ground Zero". :)

kelseymh3 years ago
Hey, hey, hey! That's "luminous spheres of self-sustaining nuclear fusion" to you, buddy!

This is extremely awesome (and physics, too :-). I just wish the G-M kit was less expensive -- you could drive each strand from a separate counter, and have a muon-telescope (or air shower detector) tree!
nikkipugh (author)  kelseymh3 years ago
I stand corrected and will use the correct term of address in future :)

*adds "2 x Geiger counter and a packet of muons" to Santa's list*