Michael Kohn - drag racing tree

CONTENTS

Drag Racing Christmas Tree For R/C Cars

More electronics projects on mikekohn.net here.

June 9, 2010

Introduction

This is a two part circuit I made for racing R/C cars. The first part is a drag racing christmas tree running on an ATtiny2313. There are 3 yellow lights, 1 green light, and 1 red light on each side. After pushing a button, there is a couple seconds delay and then the top yellow lights turn on. The lights drop down the tree making beeping noises similar to early 1980's car racing games until it hits green, which signals the drivers of the R/C cars that the race has begun. There is an infrared emitter/detector at the front to detect if someone starts before the green light. In that case they will get a red light on their side and automatically lose. At the end of the track is another circuit with an ATtiny13, 2 LED's, and the infrared sensor again which will light up the side of the car that breaks the IR beam first.

Video

I posted a sample video here: http://www.youtube.com/watch?v=xlghOGqn3ds. Unforunately those cars are cheap and hard to control. The surface of the table is too slippery and the cars only have forward, back, left, right as a digital on or off.

Pictures

	Front view of the starter circuit with 2 radio controlled cars. this shows the car on the left moving forward early and faulting, turning on a red light.
	This is a side view of the same thing.
	This is a close up of the starter circuit. Notice the infrared detector and receiver on both sides are covered with black shrink tubing (unshrunk) just to make sure ambient light doesn't affect the sensor.
	This is the simpler end of track circuit that would exist at the end of the race track to detect who has won the race.
	Schematic for the circuit. I separated out the IR proximity detector part of the circuit. This will be needed 4 times.

Source code
drag_race.asm - ATtiny2313 firmware for star of the race track.
drag_race_end.asm - ATtiny13 firmware for the end of the race track to detect the winner.