Ray Carlsen, long-time Commodore repair technician, is now selling Computer Saver (an improved version of his original Computer Saver, the schematic of which had been on his website for years).
This shows a small run of the Computer Saver I designed. It is made to be installed between any C64 and its power supply. The two LED’s on the Saver case are indicators of the PS status. The LED on the left monitors the 9VAC from the supply and it should be on all the time the PS is plugged in to AC power, whether the computer is on or off. The other LED (marked “failsafe”) is normally off. It only comes on if the PS fails due to a shorted internal regulator. That fault is what damages chips in the computer, most often the RAM. Since there is already an LED on the computer case which monitors the regulated +5VDC, one on the Saver was considered unnecessary.
Like the original, Ray’s new Computer Saver functions as a voltage limiter when plugged in-line between the C64 and the C64 power supply.
The cost of the Saver is $50.00 USD. That price could be reduced somewhat with a larger production run, but unless there is greater interest in this device, I’m not ready to tool up for that. More than half that amount was spent for parts, including shipping. Any time something is hand-made and parts are individually purchased, the price of the end product will be higher than people expect. The construction of a stand-alone device is normally higher than the same circuit built into a computer such as the C64. That’s due to the added expense of a case, cable wire and connectors as well as the added time it takes to assemble the device. There are few shortcuts, so the price is firm.
Because the protectors LED’s are on its case, Ray decided to make the cable between it and the computer rather short, about one foot long, so those LED’s can be monitored. If desired, that cable can be made longer so the protector is off the desktop. However, very long cables will reduce the voltage at the computer since it draws nearly one Amp in normal operation. The short cable seemed like the best arrangement.