You cant just use a resistor if current varies as voltage will vary too.
A regulator might be best way to go ?
Look up LM317.
A regulator might be best way to go ?
Look up LM317.
A buck converter can be bought as a ready made solution and doesn't produce waste heat.
You must give details of your application for anyone to give the most appropriate answer.
You must give details of your application for anyone to give the most appropriate answer.