Electrical energy is used to power many devices we use daily. However, the type of energy--direct current or alternating current--often differs from device to device. Even when several devices use the same type of electrical energy, these devices may have different voltage requirements. To operate the widest array of electrical devices, you will need to know how to change electrical energy from one voltage to another. As an example, let us consider how to convert a 12 volt energy source into a 6 volt energy source.
Conversion from 12V DC to 6V DC
One way of converting from one voltage level to another is by means of a circuit called a "voltage divider." All circuits behave in the manner explained by Kirchhoff's Voltage Law, which explains that the sum of the voltage drops in an electrical circuit will equal zero. Creating a voltage divider is one practical application of that law.
To create a voltage divider that will provide a 6 volt DC output from a 12 volt DC power supply, you will need two electrical resistors of equal resistance. Connect the resistors in a series circuit and connect the free leads across the 12 volt power supply.
According to Kirchhoff's Voltage Law, since each resistor in the circuit provides half of the total resistance in the circuit, the voltage differential across either one of the resistors will also provide half the voltage in the circuit.
Conversion from 12V AC to 6V AC
Another way of converting from one voltage level to another is by using a step-down transformer. A transformer preserves the power level in a circuit by raising or lowering the voltage level, and performing the opposite function in equal magnitude with electrical current. For example, if a 12 volt AC, 2 amp power supply is attached to a transformer that reduces the voltage level to 6 volts AC, the electrical current is increased to 4 amps.
Since electrical transformers work by means of an alternating magnetic field through the transformer core, attaching a transformer to change the voltage level only works if the transformer is attached to an alternating current circuit.
To change 12V AC to 6V AC, use a 2:1 transformer, and attach the 12 volt power source to the side of the transformer with more windings. When the power source is activated, there will be 6 volts AC between the two unattached transformer leads.