Analog Electronics
Completed

Cascaded Three-Transistor Human Electric Field Sensor

Sensitive detector for human electric fields using transistor amplification chain.

4 months
2 members
Analog Electronics
Analog Electronics · Bio-Sensing · Human-Body Detection
Cascaded Three-Transistor Human Electric Field Sensor

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 ⚡

BJT Circuits
Analog Design
SPICE
Bio-Sensors
PCB Design

Key Innovations ✨

  • 3-stage transistor amplifier
  • 10MΩ input impedance
  • 86dB voltage gain
  • 0.5-1.5m detection range
  • Battery-powered operation

Applications 🌐

Analog Electronics
Bio-Sensing
Human-Body Detection