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Non-Lethal Electrical Defense

Non-Lethal Electrical Defense. ECE 345 Spring 2002 Stephan Nalywajko Brian York. Project Overview. FPGA controlled state machine Keypad input Indicator LED outputs Touch sensor Sensitive to all contact Zapping circuit Integrated with touch sensor. Motivation.

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Non-Lethal Electrical Defense

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  1. Non-Lethal Electrical Defense ECE 345 Spring 2002 Stephan Nalywajko Brian York

  2. Project Overview • FPGA controlled state machine Keypad input Indicator LED outputs • Touch sensor Sensitive to all contact • Zapping circuit Integrated with touch sensor

  3. Motivation • Aftermath of September 11th • New use for existing technology • Apply knowledge from other ECE classes ECE 311 Embedded Systems ECE 330 Power Circuits • High probability of success

  4. Design Challenges • Proper isolation of 4 distinct power sources 120Vac from wall 120Vac from triacs 5Vdc for logic 1000Vdc for PAIN • Physical isolation for high voltage on the touch plate

  5. FPGA • Multiple state machines • Multiple clock frequencies • Volatile memory • Very low output current • Sparse free I/O pins

  6. Touch Circuit • Inputs: 120Vac Touch plate • Output: Triac driven 120Vac • Capacitive touch sensor calibrated with RC network

  7. Touch Circuit

  8. How do we isolate 1000Vdc from our touch sensor while still connecting them to the same touch plate? How do we read a variable AC voltage from the touch sensor? Ideal solution, two 1000V relays. Our ad hoc solution, one lawn tractor solenoid. Major Problems • 3 weeks and 5 designs later, a bridge rectifier with BJT optocoupler and 100uF cap.

  9. Half-Wave Rectifier

  10. Bridge Rectifier with Optocoupler

  11. Future Improvements • 1000V relays • Improve shocking circuit • Modify touch circuit to detect gloved hands • Modify triac circuits to give a true 0Vac output • Optimize VHDL to fit in 256K EEPROM

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