Thinkpads Forum

Hi,

The Maplin car adaptor does not have a plug which fits the T60. While my friend is trying to make one he may not succeed as he cant figure out why the AD/DC adaptor has three terminals in it.

Can anyone recommend a car adaptor? I've seen the Targus combined one but it's quite expensive. The Maplin adaptor cost me £25.

If anyone is interested, the reason for the adaptor is to complete my solar panel setup. I purchased a 50W solar panel and sealed lead-acid battery to power the laptop. I have internet via 3G.

I generally stick with the IBM AC/DC combo adapters. You can usually find them on eBay using 22P9003 as the search term.

Not clear on where you are seeing three terminals. Is this at the end of the DC power cord (i.e., the plug that goes into the laptop)? Or are you talking about where the cigarette lighter cord plugs into the adapter? On the IBM combo adapter, there's actually a 4-pin plug being used to supply power from the vehicle to the adapter:

http://www.kawakami-ca.com/images/ibm_dc_cable.jpg

Two are for +12V and the other two are ground. It may be that a pair of connections are being used in order to handle the couple of amps of current.

If your adapter has three connections to the input of the power adapter then it's possible that the third one is an extra ground (as you say there's no power on it). If, however, you are talking about the plug that goes into the laptop, then the third terminal is probably being used as a "sense" line to monitor and/or regulate the voltage. That can happen as you are using a "universal" supply which uses different plugs which control the voltage being supplied to the laptop.

edit: Ignore this... this is the 16VDC version, not the one for a T60

The yellow tipped plug which goes into the back of the laptop has three terminals on it. One is the pin, and then the outer cylinder is actually made up of two cylinders (inner & outer).

It seems that the 20V DC is carried in the cylinders. We're not sure what the pin does though!

Duh! Just goes to show you that I don't always read which conference I'm replying to and that my speed reading course from back in high school didn't do much for my overall comprehension (you mentioned T60 but it didn't register).

I don't have a 20V adapter with me at the moment so I can't measure what voltage is showing up on those three terminals, nor check continuity. If you don't get an answer by this evening (USA Pacific time), then I'll look at the one I have at home.