> The huge 170W power brick is the reason not to just move to it now, since I have a fleet of 90W AC adapters I've been using for everything since the T60.
Can't you get a barrel connector on top of a modern GaN adapter? It should be much smaller!
Can't you get a barrel connector on top of a modern GaN adapter? It should be much smaller!
You may need a circuit to negotiate the USB-PD, then to ouput 20V from that, but it should be possible.
It could even be a very interesting project: expose an artificial resistance on the barrel plug to simulate the Lenovo AC wattage resistor by matching what the USB-PD can deliver.