555 Timer Ignition Coil Driver Design

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Parts are selected: NE555P, IRF840 TO-220, screw terminals, a high-voltage TVS clamp, and a 1N4007 supply-protection diode. I’m adding the timing network and required 555 decoupling now.

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I renamed the project to 12V 555 Ignition Coil Driver, set a matching description, selected library-backed parts, consulted the NE555 and IRF840 datasheets, added the schematic components, and wired the main circuit.
Current schematic includes:
  • U1 NE555P astable timer on a protected 12 V rail
  • Q1 IRF840 low-side MOSFET coil switch
  • J1 12 V input terminal
  • J2 ignition coil primary terminal
  • D1 P6KE200A TVS flyback clamp from MOSFET drain/coil low node to GND
  • D2 1N4007 reverse-polarity protection diode for the 555/control rail
  • Timing network: R1 1 kΩ, R2 6.8 kΩ, C1 100 nF for roughly 986 Hz
  • Required 555 support: C2 10 nF control bypass, C3 100 nF decoupling, C4 10 µF bulk
  • Gate drive: R3 47 Ω gate resistor, R4 100 kΩ gate pulldown
Blocked now because the account has no available ACUs, so I couldn’t run the final design review or fix any ERC/DRC findings. Remaining work: run review, resolve any violations, then create bring-up documentation before moving to PCB layout.
Run design review
Adjust to 100 Hz
Check gate drive
Add safety note
Plan PCB layout
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12V 555 Ignition Coil Driver

12V 555 Ignition Coil Driver thumbnail
12 V NE555 astable ignition-coil driver using an IRF840 MOSFET low-side switch with gate conditioning, decoupling, input/output connectors, and flyback clamp protection.

Properties

Properties describe core aspects of the project.

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