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need to convert 12 volts to 6 volts @ about 4-6 amps

I don't know if I am in the right category - if I am not somebody
please direct me there. What I am looking to do is to use a 12volt
car battery to run 6 volt electrical motor. It used to use 6volt 4
amp/h battery. I wold like to find out if there is a way of convering
the power from car battery without waisting any juice. I think I can
just take some wire and wrap it into a coil and run my positive
through that, but then I will be loosing the juice. It might not be
enough to worry about, but, I would like to know the specifics. there
might also be another way - which I don't know about. I would also
like to keep it cheap if possible.
please if you have any ideas -let me know. thanks
 
N

Nobody

Jan 1, 1970
0
I don't know if I am in the right category - if I am not somebody
please direct me there. What I am looking to do is to use a 12volt
car battery to run 6 volt electrical motor. It used to use 6volt 4
amp/h battery. I wold like to find out if there is a way of convering
the power from car battery without waisting any juice. I think I can
just take some wire and wrap it into a coil and run my positive
through that, but then I will be loosing the juice. It might not be
enough to worry about, but, I would like to know the specifics. there
might also be another way - which I don't know about. I would also
like to keep it cheap if possible.
please if you have any ideas -let me know. thanks

The standard mechanism for efficiently controlling power to DC motors is
pulse width modulation (PWM). IOW, you turn the current on and off rapidly.

The alternative (dropping voltage across a load resistor) is going to
waste 50% of your power. If the motor draws a lot of current, you would
need a high-power resistor, which may well cost more than the components
required for PWM.

Essentially, you need:

1. A transistor (bipolar or MOSFET) which can take the motor current.
2. A diode with the same current rating.
3. A square wave oscillator, typically running at a few KHz (for a fixed
ratio, a 555 is the obvious choice).

Connect the motor between the +12V supply and the collector or drain of
the transistor. Connect the emitter or source to the ground (0V) line.
Feed the square wave to the base or gate (for a bipolar transistor, via a
resistor). Connect the diode across the motor with the *cathode* to the
+12V supply.

If you can provide the specifications of the motor (preferably the
current; failing that, the power), someone may be able to recommend
specific components.
 
J

John B

Jan 1, 1970
0
I don't know if I am in the right category - if I am not somebody
please direct me there. What I am looking to do is to use a 12volt
car battery to run 6 volt electrical motor. It used to use 6volt 4
amp/h battery. I wold like to find out if there is a way of convering
the power from car battery without waisting any juice. I think I can
just take some wire and wrap it into a coil and run my positive
through that, but then I will be loosing the juice. It might not be
enough to worry about, but, I would like to know the specifics. there
might also be another way - which I don't know about. I would also
like to keep it cheap if possible.
please if you have any ideas -let me know. thanks

This question should be in sci.electronics.basics.
 
D

DigitalRaptor

Jan 1, 1970
0
I don't know if I am in the right category - if I am not somebody
please direct me there. What I am looking to do is to use a 12volt
car battery to run 6 volt electrical motor. It used to use 6volt 4
amp/h battery. I wold like to find out if there is a way of convering
the power from car battery without waisting any juice. I think I can
just take some wire and wrap it into a coil and run my positive
through that, but then I will be loosing the juice. It might not be
enough to worry about, but, I would like to know the specifics. there
might also be another way - which I don't know about. I would also
like to keep it cheap if possible.
please if you have any ideas -let me know. thanks

If you are needing something in a 12 volt system, but need to pull 6
volts off to power something else, couldn't you just use two 6 volts
batteries wired in series to run the 12 volt stuff, but then tap
directly into one of the 6 volt batteries to power the 6 volt motor?
 
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