I have a Windows tablet with a charger which crapped out. The old charger was 12V / 1.5A - fairly standard but it had a rare tiny pin connector. Rather than buy a new charger, I decided to cannibalise another 12V / 1.5A charger I had with a different connector. I snipped the wires on both chargers about mid way, and rewired them using a block of those plastic wire connectors surrounded by some insulating tape. Not pretty, but secure. The charger works fine.

Recently, I read that a cheap, two pin fitting LED bulb could be highly dangerous. Because the bulb can be inserted either way, the capacitive dropper which protects you from the live wire could easily be connected to the neutral, leaving the live unprotected. A 50/50 chance. While I do steer clear of these cheap LED bulbs, it got me thinking about my DIY charger.

  1. Is there a risk that I've created a dangerous charger?
  2. Is there a 50/50 chance the connector pin is live? If so, is there a safe way to rectify it or should I chuck it and just buy a new one?
  3. Or, since the charger outputs 12V does it mean that it's safe enough?

The output of this "charger" thing should be isolated from the AC line internally. There should be no direct connection between the output and either side of the AC line.

Usually these things full wave rectify the AC, chop it up at high frequency thru a transformer, with a opto-isolator providing feedback from the output side to kill the oscillations when the output voltage gets above the setpoint.

In any case, soldering a different connector to the output isn't going to change whether the charger is isolated and safe or not. If you bought it from a reputable supplier and you can be confident the CE or UL mark on it is real, there is nothing to worry about.

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  • \$\begingroup\$ Note that a CE mark is not a NRTL (nationally recognized testing laboratory) mark like UL is. It only means that you claim to meet certain standards, not that an independent lab has tested it. \$\endgroup\$ – Jon Custer Jan 5 '15 at 23:24

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