By LDR (9 years old) (+dad)

LDR logo


In this game, you roll coins down a ramp onto a board with foil islands. When the coins make a bridge from one side to the other, it is a complete circuit and an LED lights up.


Version 1

Simple series circuit with LED. The coins make a conducting ‘bridge’ across the foil ‘islands.’

Version 1

First, I cut out the box and the foil islands. Then I stuck the islands onto the box and two rails along two opposite sides with glue. We made a circuit that made a LED light up and connected that to the rails with paper clips.


When coins made a “bridge” between the islands, the electricity flows and lets the LED light up. (We soaked the coins in vinegar to make them shiny and conduct well).


I made a ramp to roll the coins down out of cardboard and the game worked….


But not well enough!

Version 2 (writing the Node-Red)

We improved the game using a Raspberry Pi and Node-Red. I wanted a timer to make the game more exciting. We had a traffic light, so I used that by putting it straight onto the output pins of the Raspberry Pi.


We connected the two side rails to input pins on the Raspberry Pi so that it could tell if the coins had made the circuit complete.


I used a buzzer to tell you when the time was up.


I also used a switch to start the game. The green light went on for 20 seconds. Then the amber light came on for 20 seconds. Then the red light came on for 20 seconds. Finally, the buzzer went off.


If the coins made a bridge before the time was up, all of the LEDs flashed.


Node_Red Code


The Node Red code showing the start switch sequence and the ‘you won’ sequence.


The game is fun to make and fun to play. It is a good project because it teaches you how to programme a real game, not just on the screen.


Final Version


The full Node-Red version



LDR (9 years old)