Light Sensors
Working with photodiodes, phototransistors, and light-dependent resistors.
Light sensors convert optical radiation to electrical signals. From simple LDRs for ambient light detection to fast photodiodes for optical communication, each type has distinct characteristics.
Objectives
- Understand photodiode, phototransistor, and LDR characteristics
- Interface photodiodes in photovoltaic and photoconductive modes
- Design transimpedance amplifiers for photodiodes
- Select appropriate sensors for speed vs sensitivity tradeoffs
- Implement ambient light sensing circuits
Key Takeaways
- Photodiodes: fast, linear, need amplification
- Phototransistors: high sensitivity, slower response
- LDRs: simple but slow and nonlinear
- TIA converts current to voltage with controlled gain