I am looking to supply a bit of kit with 5 volts. I hate switching power supplies and the obvious answer is to swap to a linear power supply.

Currently the kit is powered from a laptop computer via USB but the computer itself is powered from the ubiquitous switching power supply.

I was thinking if I switch off the mains power to the computer and let it run on it’s batteries will I get a clean 5 volts or will the internal machination of the computer conspire to dirty the USB 5 volts