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.

Open Hornet 16-channel 28 V magnetic-hold coil driver for Honeywell ET switches. Arduino Mega/Pro Micro logic inputs drive low-side 100 V MOSFET channels for ET switch magnet coils with common ground, fail-safe pulldowns, 100 V flyback protection, dedicated 28 V coil input, and conservative high-current 4-layer PCB routing.