1999 iBook

A 1999 Clamshell iBook would have used an Apple 45W Power Adapter ("yo-yo" form factor). It may have a text including something like

Input: AC 100-240V 50-60Hz and Output: 24V ⎓ 1.875A.

The DC-out barrel connector is a special model with a centre (approx. 3 mm diameter) plug and a larger outside sleeve.

You should be able to find power adapters through online dealers or an online auction site. If you buy, make sure that the adapter is intended for this very iBook (not another model needing a different adapter/plug).

Addendum

There are barrel connectors of a similar design, but with a smaller centre plug. So, look at the the plug (inside the large sleeve), and compare it to the DC-in power port of the computer.

As always with power adapters, for safety reasons, quality is important. Make sure that an advertised "Apple" adapter is an original Apple adapter. If it is a used item, check that it is in good condition.

The beautiful designed power adapter for the iBook Clamshell has a Plug with 9,5mm external diameter. see

The inner power supply jack is ∅ 3.5mm for Clamshell iBook and ∅ 2.5mm for the new iBooks and PowerBooks (2001 and newer)