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BD243 DIY Mini Tesla Coil Prototyping Kit

BD243 DIY Mini Tesla Coil Prototyping Kit

High-Voltage Wireless Power Demonstration – Build Your Own Spark Gap Tesla Coil

Introduction

The BD243 Mini Tesla Coil Kit is a DIY prototyping set that lets you build a functional tabletop Tesla coil using the BD243 power transistor. This educational kit demonstrates wireless power transfer through resonant inductive coupling and produces impressive electrical arcs.

Mini Tesla Coil Kit

Key Features

High Voltage

Generates 50,000+ V arcs

🔧 DIY Assembly

Complete through-hole components

📡 Wireless Power

Demonstrates resonant coupling

🎓 Educational

Learn high-frequency AC principles

Kit Contents

BD243 Transistor1x Power NPN transistor
Primary Coil3-turn thick copper wire
Secondary Coil800-turn enameled wire
Capacitor Bank4x 0.1μF 1kV ceramic caps
Spark GapAdjustable screw terminals
Base BoardPre-drilled prototyping PCB
Power Supply12V 2A DC input
ToroidAluminum foil covered sphere

Technical Specifications

Input Voltage12V DC (2A minimum)
Resonant Frequency200kHz-1MHz (adjustable)
Secondary Coil800 turns, 28AWG enameled wire
Arc LengthUp to 2cm (depends on tuning)
TransistorBD243C (60V, 6A)
Dimensions100mm diameter × 150mm height
Safety FeaturesOn/off switch, insulated base

Assembly Instructions

  1. Prepare the Base: Mount all components on the prototyping board
  2. Wind Secondary Coil: Carefully wind 800 turns of enameled wire around PVC pipe
  3. Assemble Primary: Create 3-turn spiral coil from thick copper wire
  4. Install Capacitors: Solder four 0.1μF capacitors in parallel
  5. Mount Transistor: Attach BD243 to heatsink with thermal paste
  6. Connect Spark Gap: Adjust screw terminals to 1-2mm initial gap
  7. Add Toroid: Secure aluminum-covered sphere to top
  8. Final Check: Verify all connections before powering
Assembly Diagram

Schematic Diagram

Circuit Schematic
Note: This is a basic Slayer Exciter circuit using the BD243 transistor as the oscillator

Tuning Procedure

  1. Power on with 12V supply
  2. Adjust spark gap to 1mm initially
  3. Observe if arcs form at toroid
  4. If no arcs, slightly increase gap
  5. For maximum output, adjust primary coil taps
  6. Fine-tune by moving primary coil up/down secondary
  7. Optimal tuning occurs at loudest buzzing and longest arcs
Safety: Always use insulated tools when adjusting while powered

Safety Precautions

High Voltage Protection

  • Never touch components when powered
  • Keep flammable materials away
  • Discharge capacitors after power-off

Electronic Safety

  • Use proper heatsinking for BD243
  • Ensure adequate power supply (12V 2A+)
  • Check for shorts before powering

Operational Limits

  • Limit continuous operation to 2 minutes
  • Allow cooling between demonstrations
  • Monitor transistor temperature

Troubleshooting

No Arcs

  • Check spark gap adjustment
  • Verify secondary coil continuity
  • Ensure proper primary-secondary orientation

Weak Output

  • Increase input voltage (up to 15V max)
  • Optimize primary coil positioning
  • Check capacitor bank connections

Transistor Overheating

  • Improve heatsink attachment
  • Reduce duty cycle
  • Verify proper base resistor value