How can you do the 12 volts reduce to 6 volts?

Answer 1

It really depends on your circuit. I can give just a generic answer for a simple circuit, simple being a voltage source and some resistances.

Ampere is a measurement of current. The ratio of voltage to current is resistance (V/I = R or V=IR is a more typical notation).

So your question starts with V = 12 and asks how to lower I. I am going to assume V is a constant source, so to lower I all we need to do is increase R. Once we increase R, I will automatically decrease so that the relationship V = IR is held constant. So first determine what you want your I to be, and then add resistors in parallel or series in order to get an R that keeps the voltage constant. or, to put it another way: The current, or Amperage, or the quantity of Amperes, flowing in any simple electrical circuit (at any given voltage) may be lowered or decreased by increasing the resistance in the circuit according to Ohm's law: V = IR, or in this case, its equivalent I = V/R The resistance may be increased, logically enough, by adding a resistor, a device with less than perfect conductance, originally made from carbon or thin wire. Or, if there is a variable resistor (a Rheostat) in the circuit, it may be adjusted to increase its resistance. Electronic devices, such as transistors or vacuum tubes, can also provide variable resistance in a circuit.

Answer 2

That depends a lot on how much current you need and what you want to use it for. You could use a voltage regulator, for instance.

If it's for really low and constant currents, you could use a resistor or a few diodes in series with the load.