12 vdc to 4.5 volts transformer

[Inferno]

hello..
i need to transfrom a 12 vdc source ( battery ) to 4.5 volts ... how could that be done ?? does any one have a good circiut ?? :?:

 

[ante]

If the required current is less than 1A the LM317 is a good choice.

Ante :roll:

 

[stevez]

There are several ways to reduce the voltage. Current or power requirements must be known.

If voltage regulation is not an issue then a resistor could accomplish the task if the load is constant. If the load varies or regulation is important then regulators like the LM317 might be a solution - dependent on current and stability requirements. Any of these methods are somewhat wasteful since as 7.5/12 of the total power is lost to heat. On top of the waste the heat has to go somewhere - sometimes that's a bigger problem.

There are power supplies made with discrete components or ICs that can provide the reduced voltage with less waste in power. The complexity and cost of the power supply goes up so you have to decide if it's worth the trouble. In most cases the resistor or simple linear regulator (LM317) is good enough.