Electricity Primer

Shielding

• Hard to do right
• Emissions hit shield and travel back to ground with resonance

Size of circuit

• Circuits are always loops, and loops will resonate like antennas at a frequency determined by their size
• The smaller the loop, the higher the frequency
• Higher frequencies have a smaller potential to interfere with circuit frequencies
  • Keep hookup wires short

Multiple power sources

• USB is one source, wall and battery power is another
• With only one device, not really a problem
• With more than one device, you create a closed loop between the two devices and the power source
  • Electrons can return via the grounds connecting both devices and the PC motherboard rather than just straight to wall or battery ground
  • Solutions:
    • Make the connections between all devices and battery or wall really desirable to electrons
      • Low resistance
      • Big fat wire
      • As short a wire as possible
    • Use a USB isolator
    • Use Ethernet for data rather than USB (or wireless), only for future Phidgets

Introduction

This primer will help you