Hello All

I'm looking for a sensor that can detect a thin black line (about 2mm) on a white background and at a distance of about 1/2 inch away.

Thank you

 

Shine an LED down then "see" the black line with a photo-transistor.
Look in Google for Line Following Robot Circuit.

 

Hello,

Take a look at the attached PDF.
It comes from this page : http://www.educypedia.be/electronics/robotics.htm
There is more information on sensors and motors over there.
Motor and generators: Brushless DC motors Motor AC Motor-Synchronous Single phase AC motors Generators Motor DC Robot Stepper motor Generator: asynchronous Motor overview Servomotor Stepper motor drivers
http://www.educypedia.be/electronics/circuitssensorslight.htm

And a lot of genaral electronics.
Electronic circuits: Verticaal 1 wire circuits Infra Red Circuits RF-Crystal radio Application notes LED circuits RF- FM transmitter Analog circuits Measurement Sensors Audio Micro controller Sensors-fluid Audio amplifiers Motor control circuits Sensors-Light Battery chargers Opto electronics Sensors-sound Computer Power - control Sensors-temperature Digital circuits Power supplies Sensors-weather Fluorescent Lamp Power supplies-SMPS Telephone technology General RF circuits Video circuits
Greetings,
Bertus