A resistor is easiest if the supply voltage and current draw
are fairly constant. You didn't indicate what sort of
device you are trying to power; some are much more forgiving than others.

Voltage divided by Current = Resistance
(3 volt drop/1 ampere = 3 ohm resistor)
Current squared times resistance = power in watts
(1 x 1 x 3 = 3 Watt resistor - get a 5 watt for safety)
So you need a 3 ohm 5 watt resistor

Bart Bervoets wrote:
Power resistor or voltage regulator?
Anyone a simple diagram?(if i need one)
Draw is about 1A but i would like to have some tolerance.

Bart Bervoets