Hacktronics sent us another goody package, containing a very cool LCD Shield, a couple protoshields, and these IR emitter/detector pairs. The TCRT5000 is a reflective sensor which includes an infrared emitter and phototransistor in a leaded package which blocks visible light. The "blue" LED is the IR emitter.
These units have been used for:
• Position sensor for shaft encoder
• Detection of reflective material such as paper, IBM cards,
magnetic tapes etc.
• Limit switch for mechanical motions in VCR
• General purpose - wherever the space is limited
Our goal is to make a tachometer for tools and testing rigs. One of our projects is a motor test jig. We are measuring volts and amps using our previous amp hour meter project, and now want to make sure the motor is turning the correct rpm.
E (emitter) to GND
C (collector) to a digital input pin, and to +5v through a 10K resistor.
C (cathode) to GND
A (anode) to a 150 Ohm resistor, with the other end of resistor to +5V
This project will entail the use of hardware interrupts, which the following video touches on. Code samples to follow soon.