[avion8706]

I am trying to find a voltage regulator or DC/DC Converter to meet
my specifications. My input voltage is 12VDC (600A) and I need an output of 9VDC.
I've found many that are readily available with that voltage specification,
such as the 7809, but they all seem to regulate the amperage at 1-1.5A. Is
it possible to build a regulator that does not limit the Amperage. The
electric motor I am powering (Input of 9VDC required) currently draws about
18 amps and could easily draw more to achieve higher RPM's. Any information
you could offer would be greatly appreciated.

 

[duke37]

1.This is getting into the realm of power engineering.
2.The current output of a 7809 can be multiplied by adding by-pass transistors. A 7909 may be easier to use.
3.The motor will need more voltage as well as current in order to go faster. What type of motor is it?
4.The amperage will always be limited at some level. All metals can melt!

There are 13.8V power supplies to run small transmitters, it may be possible to bodge one of these to give a lower voltage.

 

[avion8706]

I am using a Novac 17.5 brushless motor with a DC powered Electronic Speed Control (ESC). When I bought it I was told not to exceed much above 9 volts or I may fry the motor. Currently I'm using around 72 AA alkaline non-rechargeable batteries wired in a combination of series and parallel to achieve around 9 VDC and 18 Amps. As you can probably guess it works well and I can achieve extremely high RPM's but it doesn't last very long. I am simply trying to find a single rechargeable battery that can give me the same results. But all of the batteries I've found that can deliver that kind of current are 12 volts or higher. What would you recommend?

 

[(*steve*)]

What would you recommend?

PWM with a duty cycle limited to 75%

 

[ElectronWorks]

try the LTC3890. This is a dual buck converter and you can connect the 2 outputs together to make one big output. Moreover you can simulate the design before you even heat up your soldering iron.

http://www.linear.com/product/LTC3890

http://www.simonbramble.co.uk/lt_spice/ltspice_lt_spice.htm

For the FETs, try Fairchild or Vishay. For the inductor look at Coilcraft