Voltage regulator help

[crashmasher]

Hey,

My experience for circuits and such is just down to a minimum, i get the jist of how things work but be patient as i am not an expert. I have just started a project for building led light for my friends rc car. He wants to use a 9v battery so first off i though that resistors would do the trick, but thinking more into it i realized that the leds would just get dimmer as the battery ran below a about 8.5, im looking for full brightness at all times. Now the voltage regulator comes in, i bought a LM1117 Low Dropout Voltage Regulator 3.3V 800ma and wired it up. now I can get 3.3v at all times until the voltage drops below about 4.5v. Now my problem. HEAT, the regulator creates a huge amount of heat. I'm fine with a small heat sink (which i was planning on having anyways) but it seems that only a very large heat sink would cut it, which seems ridiculous considering that they are just leds on an rc car. Is their a way to wire resistors into the circuit to lessen the heat? or is their a simpler way that i am just not seeing

Thanks in advance to whoever feels like dealing with my lack of knowledge

[FOOKz™]

The dissipated heat is inevitable. Your circuit will emit heat from the resistors and the regulator no matter what you do but the more components that share the "load" of the heat it may seem like its not s hot.

Wiring resistors in series with the regulator is the simplest way to do it. If you do it should be at least a nice fat 1 watt resistor.


(see diagram attached)
Adjust the value of R_x so you read 4v across the resistor, and/or you read 5v across the voltage regulator input.

[crashmasher]

Yea, this is what i thought i might have to do. thanks a lot for the help and the diagram. I will stop by the store and pick up some resistors

Thanks again