1. Diodes Part II Intro to ECSE Analysis K. A. Connor
Mobile Studio Project
Center for Mobile Hands-On STEM
SMART LIGHTING Engineering Research Center
ECSE Department
Rensselaer Polytechnic Institute
Intro to ECSE Analysis

2. Outline LED as Optical Transmitter
Photodiode or Phototransistor as Detector
Applications

3. Optical Transmitter/Receiver
LEDs can produce light pulses for digital communications
They can also have their intensity modulated with an analog signal

4. Optical Receiver
Photodiode I-V curves change in lower left quadrant when exposed to light.
Current produced can be detected.

5. Optical Receiver Could use a photocell (variable resistor)
Could use a solar cell
All have their pluses and minuses
In each case observe how the receiver responds to the transmitted light pulse … does high produce low or high, etc?

6. Applications
Opto-isolators – no direct electrical connection between input and output
Fiber optic communication
IR Remote

7. Applications
Sensors
And?