Truly "universal" laptop power adapter
I am looking for a universal power adapter to power just about all laptop computers - old and new. Just like they make a universal adapter for smaller electronics with adjustments for volts and amps, I need one for laptop computers. I receive a lot of computers for free or cheap, most of them for parts, but some of them work. Most are atleast 10 years old but some are slightly newer, maybe around 5 years or so. I usually get them without the adapters, so I would like a cheap way to test them without having to buy an adapter for each one. I would like to know whether or not to sell them on ebay for parts or as a working unit. The only way I can do this is to power them up with an adapter. So, I need some solution to this. Please advise.