Cascaded Three-Transistor Human Electric Field Sensor
Sensitive detector for human electric fields using transistor amplification chain.

Technical Deep Dive 🛠️
This analog design project created a sensitive detector for the weak electric fields naturally emitted by the human body, enabling touchless interaction. Circuit Design: • 3-stage common-emitter NPN amplifier • High-impedance input stage (10MΩ) • Bandwidth: 0.1Hz to 100kHz • Voltage gain: 86dB • Input-referred noise: 2μV/√Hz Performance Characteristics: • Detection range: 0.5m to 1.5m • Sensitivity: 10mV/m field strength • Power: 9V battery operation • Temperature stability: ±5% over 0-50°C Applications Demonstrated: • Touchless light switch • Presence detector • Simple gesture recognition • Sleep monitoring Future Enhancements: • CMOS implementation • Digital output interface • Array configuration for directionality
Engineering Challenges 🎯
- Minimizing environmental noise
- Stability against oscillation
- Temperature compensation
- False trigger avoidance
Achievements & Outcomes 🚀
- Working prototype demonstrated
- Published in college journal
- Potential for commercialization
- Foundation for advanced research
Technology Stack ⚡
Key Innovations ✨
- 3-stage transistor amplifier
- 10MΩ input impedance
- 86dB voltage gain
- 0.5-1.5m detection range
- Battery-powered operation