Why do you need a Power Saver for the Commodore 64? Basically, Commodore intended the computer to live for a maximum of 5-6 years and so the components chosen reflected this view - no thought went into considering what happens past this point. Now that it's 30 years later we know that the 5v regulator has a tendency to short out input and output voltage, meaning that those sensitive 5v chips will intermittenly, or sometimes even permanently, end up getting something like two or three times that... enough to melt that precious silicon! Your options are either to get a brand new power supply or combine your old one with a C64 power saver for as long as that'll still be around, running unprotected is simply foolish these days!

How does it work? The design is based on the one developed by famed C64-tinkerer Ray Carlsen, what it does is monitor the 5v line coming from your power supply and when it starts outputting voltages above 5.6v a relay is slammed shut and the line is cut. You have the option of mounting a buzzer to the board so that you can get annoyed at it until you realize it's time to buy or build a new PSU, or when mounted externally you can look at the nice LEDs to figure out wether your supply is good or not. Once a PSU has started to go bad, put a "Bad PSU" sticker on it and never use it again!

Complete BOM and pictures of the completed boxed version of this can be found on my github, see link to documentation.

NB! Some Commodore 64 power supplies use a different pin for the 5v, earlier versions of this board needed to have wires added to it in order to account for these variants - revision E already has these on the board, so you do not need to add them. See the github page for details on how to modify the earlier revisions of the boards if you already have them.