5VDC Regulator

I hope this is in the correct topic. If not' I am sorry.

I have an RC car that the main board operates correctly with 5v. I am running 8.4v to the car. It is ok and all but Im about to add some more cells and was curious how I could hook up a 5VDC, 3 pin, regulator to the car so I know the electronics gets the 5v it needs and the remaining volts and amps get transfered to the motor. I have seen it done but the guy that has this setup will not release the info on it. Please help. I will provide all the info I can on the electronics etc. if needed.

If You apply a linear regulator, cannot extend the battery life. Need a buck regulator (SMPS) for best results. Visit to National website for type selection, depending from desired power.

I can not find anything at National on what I need and/or want. Any help would be great.

If the electronics was designed to drive the motor with 5 volts, you will have to do major surgury to seperate the control and drive circuits.

Do you have a schematic? Is the power to the main board separate from the power to the motor?

Sebi is right in that a linear regulator will waste power however you may be willing to accept that in order to keep the electronics really simple.

well, i have seen that some RC cars have a regulator of 5v on them, ususally with a zenner or a 78L05 (100mA) regulator for electronics, and the part that controls the motor goes to the full power suply.
if you only need the electronics to run with 5V and the rest(motor+driving circuit) can be connected directly to the battery than the solution is rather simple. if you have a zenner circuit on board, than you might need to replace a resistor.
a good picture on the circuit would be excellent. from both sides of the PCB.