This little dude likes light

By LordGG
@ November 12, 2010

• Actuators / output devices: Autonomous
• Power source: 2 AA cells
• Sensors / input devices: Photoresistors
• Target environment: indoor flat surfaces

Hi all !

That was my first robot, a few months ago. I wanted to start from scratch, so no micro-controller here !

It is a simple photophile robot, but it was a way to discover new fields to me like :

• electronic basis
• principle of gear motor reduction 
• building a simple chassis
• making a PCB of me own

The principle

First of all, I got inspired and guided by a french book named "Je construis mon premier robot mobile" by Frédéric Giamarchi.

2 photoresistors mesure the light from 2 different directions (front/left and front/right), 2 comparators (LM393) compare the tension of the 2 photoresistors and activate (or not) one motor. A variable resistor allows to compensate the difference between the photoresistors.

Gear motor reduction prototype

Final gear motor reduction

Electronic prototype

The PCB finished and perforated

The robot head

View from below

The finished robot

The reduction happened to be a bit to strong, so the the robot was quite slow.