I'm working on a small project that needs 1.5v DC but only have in my possession a wall wart that pumps out 8.25v DC. Is there a way to (simply) reduce the voltage of the wart so that I don't fry the electronics that I'm working with? I tried linking up resistors and that changed nothing.
The circuit (a small radio) needs 1.5v / 20ma. The wart outputs
It's probably simpler to get a different wallwart. You need a regulator to bring down the voltage and keep it steady. However it will dissipate about 140mW. Or you can use one of the many switching regulator modules.
What do you mean you tried "linking up resistors?" A 330 ohm 1/2 watt resistor in series with the wall wart will probably work. If the current is as you say, it will drop the voltage to 1.5 volts. Place three diodes in series across the 1.5 volt point, forward biased, to common. This will insure that the voltage never goes above about 2 volts no matter what the radio draws. It should protect it.
This scheme has very poor regulation but I doubt the radio will care. It should work and is about as simple as you can do. Of course, regulators with more advanced electronics would be better but probably not necessary.
BTW, measure the wall wart voltage. If it is rated at 8.25 volts chances are that it will put out 12 or more volts unloaded assuming it is un-regulated. Most are. That would require a different resistor.