### Thinkpad power supply type detection (and how to fool it) ###
       
       
       The Thinkpad W530 detects the type of attached power supply by measuring the resistance between the power supply's ground (outter ring) and the 'detection' pin (central pin). Typical values are:
       
       65W = ? ohm
       90W = open (infinite resistance)
       135W = 0 ohm (shorted)
       170W = 1.5 Kohm
       
       This means that you may fool the W530 into believing it is connected to, say, a 135W power supply while the supply is of another type - just by shorting the outter ring and the central pin.