Laptop power supplies could be okay or they could be a total pain in the ass.
Some of them will put out a reasonably clean voltage all the time and others won't put out anything at all until they receive some kind of signal from the laptop (to make it harder for other companies to sell cheap aftermarket replacements for the power supply)
Some of them are probably quite RF clean and others are probably noise machines.
I would test it with a voltmeter to see if it puts out the proper voltage, and then maybe into a load like a small lamp and see if the voltage stays up. And I would probably add a couple of capacitors across the supply output for good measure, a bigger one like a 10uF tantalum electrolytic in parallel with a small 0.1uF ceramic or something.