Voltage divider is ok if your load is only few milliamps. As more load you have the more power (or heat) the series resistor has to dissipate and of course there will be voltage drop on the resistor. This means that it will be difficult to regulate the output.
2 options: 1. Use linear voltage regulator such as LM340T-5.0 or 7805. The most common version is the 1 amp version but there is a 3 amp and a 0.5 amp version. Because this is linear, heat must be dissipated. You need large heatsink if you have high load. 2. Use switch mode regulator such as LM2677. Because it is switch-mode the efficiency is close to 100, thus little heat si dissipated even at full load. Most of the time no heatsink is required and the whole circuit will fit inside the cigar lighter plug.
The 12 v side ampere rating is unnecessary information (You need 5 watts output power, so if the input is 12 volts, you need around 1/2A input current). Use a DC to DC converter. I found an IC made for this purpose at Radio Shack several years ago - I assume they are still available if you are a hobbyist. Otherwise you can buy premade ones (search for 12v to 5v converter).
3.3, 5 and 12 volts DC
Computers use variable DC voltage 12, 5, 3.3, -12, -5 volts
By a DC power supply that runs at 230 volts AC. Basically, you need a full wave rectifier (4 diodes) to convert AC into all positive voltage. Then you need capacitors to smooth out the ripple and then various resistors to reduce the voltage.
If it is AC voltages you need to convert, you need to find a transformer to do this job. Without knowing the application it is hard to guess what you are trying to do.
5000 volts
To calculate the amperage at 12 volts based on 1.5 amps at 5 volts, you can use the formula P=IV (Power = Current x Voltage). First, find the power at 5 volts (P=1.5A * 5V = 7.5 watts). Then, using P=IV at 12 volts, solve for current (7.5W = I * 12V => I = 0.625A). So, at 12 volts, 1.5 amps at 5 volts translates to approximately 0.625 amps.
Because alternating current (AC) voltage varies over time, to the positive and negative, an actual AC voltage measurement will not be the same as a DC voltage measurement. For example: 5 volts DC is 5 volts constantly, viewed over time. The average voltage is 5 volts. 5 volts AC (from zero to peak) is not actually 5 volts constantly, but varies between 5 volts and 0 volts over time. The average voltage will not be 5 volts. Using RMS AC values is designed to make AC and DC measurements equivalent, for example 5 volts DC and 5 volts RMS AC are almost identical.
Because alternating current (AC) voltage varies over time, to the positive and negative, an actual AC voltage measurement will not be the same as a DC voltage measurement. For example: 5 volts DC is 5 volts constantly, viewed over time. The average voltage is 5 volts. 5 volts AC (from zero to peak) is not actually 5 volts constantly, but varies between 5 volts and 0 volts over time. The average voltage will not be 5 volts. Using RMS AC values is designed to make AC and DC measurements equivalent, for example 5 volts DC and 5 volts RMS AC are almost identical.
Both 5 volts DC and 5 volts AC represent the same voltage level of 5 volts. However, the key difference lies in their waveform. DC is a steady voltage that flows in one direction, while AC alternates in direction, changing polarity over time. This difference affects how each type of voltage is used in various electrical applications.
A personal computer's power supply receives 120 volts of AC and converts it to 3.3, 5, 12 volts of DC power.Another answerThe secondary voltage could be any number of voltages depending on what the power supply was designed for. Your best bet is to get a DC voltmeter and measure the output voltage of each wire on the output side.
+3.3 volts +5 volts, +12 volts -12 volts, and -5 volts but -5 is rare