I have small collection of vintage computers. Several computers do not have PSU, other one have very specific ones. The problem is with some that looks like “standard”, have same connector like others, but have reversed polarity. Like ZX Spectrum or Commodore 16.
I decided to introduce some standard for my collection:
- The computer must accept any PSU in collection without damage to computer. It may work, o just do not work. But no damage to computer.
- The computer may harm PSU by shorting it.
- The computer must accept unregulated transformer PSU with “12V” marking (up to 16V unloaded) for few minutes without harm.
- Computers can have upgraded internal regulators. (DC/DC converters) and crowbars.
- Round connectors are “CENTER POSITIVE”.
To prevent reverse polarity, computer may have serial diodes, rectifier bridges installed.
Silicon rectifier installed in Commodore 16.
To prevent polarity errors it is possible to use 3..5A diode to short power input (assuming that PSU bricks are <3A).
