I have a 12v deep cycle battery for my wheel chair and I would like to power
a 6v radio receiver from it. I kinda of know what a voltage divider is but
do not know what values to use. I also would like for it not to waste too
much power on the side of a divider that's not used. Don't know if a
regulator or a zener would be a good idea. What would be a good circuit for
my situation? Thank you very much.
bill
I'm assuming you just want a portable transistor receiver for music?
Easiest/safest/best way would probably be a three terminal regulator
like the LM317 adjusted for 6 volts out.
It will waste half the power - but it is probably not a concern if the
radio is a portable that is designed to run on dry cell batteries,
since the battery in your chair would be several orders of magnitude
bigger/longer lasting than a dry cell - and it doesn't take much power
to work a radio.
Voltage divider isn't a good idea - the power a radio takes varies
considerably depending on the volume and type of program material it
is playing - the voltage would fluctuate a lot - and you need to know
the average current and high and low to calculate a resistance divider
(or even learn if it might work OK) - you might get away with it if
you just use earphones at moderate volume. You need to know current
drain of the radio for a calculation.
Zener is a possibility - you could put one six volt type or some
combination that equals 6V in series with it - their power dissipation
will be low (hard to find high power zeners these days).
A one watt zener would give you 166 milliamps for the radio without
burning out - plenty for a small transistor receiver. If it did
overheat and short it might take out the radio.
A really good albeit a lot more complicated solution is to use a
switcher regulator like the National series of "simple switchers."
That gives you a regulated output voltage with minimal waste power.
Unless you're using a high power ham radio transceiver or like a huge
amount of bass and lots of loudness - the three terminal is your best
and easiest option.