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Choosing power supply, how to get the voltage and current ratings?

Is it possible to set up a DC source of power for a laptop so that it mimics the specs of the adapter (basically set up something with the same voltage and amperage)?

The specs I am trying to mimic are 19V and 2.42A. I'm not sure exactly how to set up something with specs near that, but I do have a model train set that can output a variable voltage amount, and using batteries might also work. Any suggestions on this would be appreciated.

I also have other adapters lying around that can be cannibalized for spare parts.

Is is harmful to laptops to use slightly too much amperage or voltage? If not I may just hook it up to a different adapter that uses 20V (I don't know the amperage, but I'd imagine it is higher).


marked as duplicate by The Photon, Michael Karas, Dave Tweed, Nick Alexeev, zebonaut Jan 13 '13 at 10:49

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  • \$\begingroup\$ Not exactly. That was about using different adapters with the same pin. I'm asking about either constructing one our of things that aren't adapters, OR switching the head on two of them that are close enough. \$\endgroup\$ – PixelArtDragon Jan 13 '13 at 1:33
  • \$\begingroup\$ I have one of those pans that was designed to cook spaghetti. Is it okay to cook spaghetti in another pan if it fits? \$\endgroup\$ – Matt Young Jan 13 '13 at 3:17

Voltage is the first thing you need to consider. You must find a regulated voltage source which matches what your laptop requires. The next step is figuring out if your voltage source has a current source which can supply enough amperes to power your laptop (in this case, it should be able to provide at least 2.42A). So what you're looking for is a power supply which outputs 19V, and can deliver at least 2.42A. If it can deliver more, that's fine. Your laptop will only pull as much as it needs.

If you do hack something together, beware that you will be working with mains power source. Also, make doubly sure that you don't get the polarity wrong.

I don't know if 20V is alright or not, you have to check what range your laptop can tolerate. I will claim, without justification, that 20V should work fine.

You can use batteries, of course. It depends a lot on what kind of batteries. If you plan on wiring up a bunch of AAs and such in series/parallel to get what you want, you may, but they probably won't last long.

My suggestion would be to buy a power adapter for your laptop. They're very common and easy to find, and will save you a lot of trouble/concern for safety.

  • 2
    \$\begingroup\$ +1 on buying an adapter and staying out of trouble. Check local swap meets or craigslist. \$\endgroup\$ – Chetan Bhargava Jan 13 '13 at 3:41
  • \$\begingroup\$ "but I do have a model train set that can output a variable voltage" the train PSU is probably unregulated and therefore a bad idea. \$\endgroup\$ – jippie Jan 13 '13 at 11:29

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