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The resistance may be increased, logically enough, by adding a resistor, a device with less than perfect conductance, originally made from carbon or thin wire.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.
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.
12 volts
12 volts
Yes, series the two batteries to produce 12 volts. Tap off of the two end terminals for the 12 volts. Tap off of the series jumper for the 6 volts of one of the batteries. The two 6 volt batteries can not be paralleled in this connection as they will short out.
Yes. Since the coil is run at full voltage when starting 12 volts may be too much for a 6 volt ignition coil. It would be at about 8 volts when running. There is a starting resistor.
6 amps
12 volts
If the voltage is AC a transformer can be used.
It is 12 volts.
No. 12 volts peak to peak would be 6 in the positive polarity and 6 negative polarity. Simply saying 12 volts AC would be 12 volts in each polarity or 24 volts peak to peak
12 volts
12 volts
Automobile batteries today are all 12 volt. Most auto manufacutures switched from 6 volts to 12 volts in the 50s.
they are 12 volts
It is 12 volts.
You need a regulator.
12V.
Reduce the primary voltage and the secondary will also drop.