Guitar pedal power supply?

Ok , this is tricky but you can easily try something here. Assuming your pedal is of standard 9-volt consumption, a lot of people mistake the fact that 9-volts isn't simply 9-volts. To a battery , yes - but when you're dealing with a 110v current reduced to 9v for pedals, there is also something called Ma, or miliamps. Look on the case of your power supply, it should have some raised type lettering and numbers - you'll see input (110v) , output (9v) and "ma" which is normally 300ma , sometimes 500ma.. The possibility could be a mismatch in miliamps between your power supply and your pedal requirements, which would cause some hum. Just check the pedal and the supply to make sure the supply is providing the correct miliamps for your pedal, if not then i bet the culprit is the supply. Then , you would get a corresponding power supply and that should make everything fine.

As long as your pedal has a adapter jack on it, then you can use it. Some adapters have a two pole terminal (like what you put your battery into inside the unit) for devices that don't have a DC input jack. Just make sure you match the polarity of your pedal with the adapter. You should see a symbol near the jack that has a circle and a curved line around it. there will be a + or a - sign in the inner circle. Set the polarity switch on the adapter to match what your pedal has.