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Larry
Join Date: Oct 1999
Location: Alamogordo, NM, USA
Posts: 908
Re: 12VDC to 6VDC
This is kind of long, but bear with me.
You can use a simple resistor circuit to reduce the voltage in a circuit.
First, you need to know the current draw, in amps, of the component and how many volts you need to drop from 12 volts, (3 to 6 volts in your case). Using Ohms Law, divide the voltage drop by the amperage draw of the component. This will give you the required resistance to use in the circuit.
Now, since there only so many standard resistances that are available, try using 3 volts in one calculation, then 6 volts. If a standard value of resistance falls within your two answers, use that value. It will get you in the range of of 6 to 9 volts the component requires to operate.
If you find a resistor that will work, now you have to determine if it will handle the power, in watts, the component draws. If the resistor is too small, it will overheat. (you can always go bigger with the wattage rating of a resistor). To do this, take the voltage drop that worked in your resistor calculations and multiply this voltage by the amperage draw of the component. This will give you the minimum wattage rating of the resistor.
Remember, this circuit will only work with a component that draws the same amperage as the one you have now. Any other component that draws a different amount of current will change the voltage going to the component.
If you can't find resistor that will work, you can build a voltage divider. It's a little more complicated, but you can get the required voltage very close to what's required. Having a range of 6 to 9 volts will help in both methods.
Let us know if this makes sense!
Larry