I had a laptop given to me for the parts, a Hewlett Packard. The jack for the battery charger is broken. The guy that gave it to me said that's all that's wrong with it and he didn't want to fix it, the user wanted to upgrade to a better one anyway. So I'm thinking I can fix that, only I don't have the wall wart. It uses 19v, 3.16amp. Anybody know how to build a circuit with these specs, or give me an idea of what I need to do it? I might can use my workbench power supply, but I don't know how to limit the current to 3.13 amps. Thanks.

 

Usually the charger is built into the laptop. All you need is a 19V power supply that can supply up to 3.13 amps. There should be no need to limit the current except to prevent damage in the event of a fault with the laptop (use a 5amp fuse). I've run my own laptop directly off a 12V battery and the input spec for that one was 16V.... 12V might be too low for your laptop though.

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My old laptop used to charge alright from 12V but it wouldn't run from it.

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