Laptop power supply "Smart Pin" ?

[k7qlk7ql]

Hi All,

I'm an electronic hobbyist and wanted to use a surplus HP laptop power supply as a power source

for my experiments.  It is a large 'brick' rated at 18.5VDC @ 6.5AMPS, I think (sorry I'm at

work).  When  I cut off the DC plug I was surprised to find a COAX type cable with 2 shields and

a center conductor.  After a little surfing I 'assumed' that the third wire is the center

conductor, or the smart pin.  Cannot seem to find how the "smart pin" works.  Anyone know of a

link as to how this works so I can be "smart" about using this power supply?  All I'm looking

for is some nice, regulated DC.

Buy the way, I own 3 HP laptops and administer hundreds of HP servers at work.  Wouldn't buy

anything else!

Thanks...

[k7qlk7ql]

I did manage to find this discussion...

http://www.techspot.com/vb/all/windows/t-137840-Smartpin-power-connector-HP-6715s.html

[engr_kef]

Hello friend, ignore those websites just cut your hp charger, u will see 3 wires which are the first layer, second and third. Cut off the third layer to prevent shunting cause it almost damage my laptop. Connect your positive to the second layer and negative to the first layer and that solves the problem. Can also be used on dell laptop chargers too. Tested and confirmed. Don't forget to cut of the third layer first. Kudos

[NicholasLEby]

Hey, did you ever find a solution for this?

I'm using a similar HP power supply (19.5vdc) as a DC hobby adapter for model trains. I cut the cable just before the barrel jack and revealed the 3 wires (white, black and blue), then used a multi-meter to determine volatages on each wire. I ended up only needing the white and black, but wondering what I should do with the blue. It reads 19.5 vdc as well. I think I read other people were opening up the brick and disconnecting it from the board in there. Thoughts? Thanks!