Commodore 64 Power Saver

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This project originally conceived by Ray Carlsen

The original Commodore 64 brick power supply can fail with a dead short across the 5V regulator, damaging its chips.

This circuit can be installed internally in a C64 computer which detects an overvolt condition and disconnects the power supply, preventing harm.

Base Component List

Purchase these parts as a kit

C64 Power Saver Schematic
  • 5v Relay, low power, 2A minimum rating or greater
  • 4.7v Zener diode
  • 1.5a fast-blow fuse
  • 470Ω Resistors (Quantity 2)
  • 2.2kΩ Resistor
  • 2N3904 or 2N2222 Transistors (Quantity 2)
  • 1N914 Diode

Optional Components

Status LEDs can also be added, as show in the schematic. LED resistor values will vary.