I want to reduce my 12 volt battery in to 7.2 volts. What is the easiest & cheapest way I could do that?

Question

I want to reduce the 12 volts from my battery into 7.2 volts. (I'm a noob at resistors) How would I go about doing this? Can some one give me a list of resistors I would use to do this, and possibly even a diagram of the circuit? The easier and the cheaper it is, the better.

Answer 1

Cheapest would be a resistor matched to the load, which you haven't told us, but that would also waste a fair amount of power. Much more reliable would be to get a voltage regulator. Since 7.2 doesn't strike me a common voltage, a variable regulator that is set with a small potentiometer for the model would be a choice.
http://dkc1.digikey.com/US/EN/PDF/T073/P3.html

Answer 2

Look up an emitter follower. IIRC you need about 7.5v in Zeners for the base and that will give you 7.2v at the output, you lose 0.3v to switch the transistor on.

See the second circuit in the second illustration below. With the Zener reference the circuit is less susceptible to variations in input voltage and this circuit has much lower output impedence than a voltage divider.

The transistor will dissipate the other 4.8v, so if you pull much current it's going to get warm in a hurry.

In the end a voltage regulator is probably easier.

Answer 3

If u use resistor or linear regulator concept it will be cheaper.
But it will consume lot of power and transform it in the form of heat. Generally these effieciencis vary from 50 - 70%. These are recommended if the total curent is less in the range of mA.

If u want good efficiency go for DC-DC converter (SMPS concept). This can provide u more than 95% efficiency thus less heat and little power consumption. These are recommended for larger currents (few mA to several amps).

All the Best !

Answer 4

For small load devices you can purchase cheaply a voltage regulator with multi tap settings.Try your local auto mobile supply shop or internet sales.

Answer 5

use a voltage divider which is two resistors in series

if you set R2 to 10k ohms then R1 will be around 6.6k a standard size is 6.8k