Mac PowerBook – Universal power supply

Many laptops these days have power supply connectors that are the same. There are ‘universal’ power supplies that can handle loads of different types of laptop, and I got one for just that purpose:

As a side note thi particular model has a USB charging socket AND can be powered from a 12V car power socket! For older laptops that do not require much power this works really well! No so well for larger laptops or ones that require higher wattage. The voltage can be set and is shown on the display.

When a PowerBook came, without a power supply, I ordered a ‘proper’ power supply from eBay…. Ah! I am not sure if I read the specifications correctly, as it seems later models used a smaller plug! The original one is like a strange 3.5mm stereo jack with a metal outer shield.

I guess at the time there were not many laptops around and Apple tend to do what the heck they like anyway! My eBay supply has what looks like a 2.5mm jack with shield and is far too small to connect to my machine… Maybe I should read the specifications in future a little better? Anyway. I knew I had this universal supply knocking about, so let’s try that.

My old PowerBook has a fried battery anyway, so I don’t care about charging it. That would mean the power rating could be less and possible no need to set and sense lines. The pinout on the plug is like this:

So the question is can you leave the sense and outer connector not connected and get some life?

Next we need some supplies. Back in the box of bits and found what we need. A female power jack and 3.5mm stereo jack:

Power adaptor “ASSMBLE!”

Some electrical tape to insulate the connections. Cant use heat shrink as the plug is very tight.

Some continuity testing to see that the positive from the power supply is connected to the largest part of the jack… It is…

Test that there are 24 Volts coming out (Don’t cross the streams!). Looks ok!

Its alive!

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