DC-DC reduction circuit needed

[polar_explorer]

Does anyone have a circuit diagram, with a parts list, for a DC-DC voltage reduction circuit. I know the principle and have general circuit diagrams, but they don't show the actual components needed (like the MOSFETs) and how they connect. I am needing to drop the main ship 12v battery to 7.2v for my bow thruster. I know there is an Action electronics module that will do that, but its 36quid so i'm looking to do it a bit cheaper DIY. The circuit will need to be able to take 4 amps. Hoping there might be an electronics genius on here somewhere.

[FrancisMcN]

Is the bow thruster either fully on or off without controlling speed in between? If so you might be able to get away with a simple dropping resistor in the circuit. To produce a drop of 4.8v at 4 amps requires a 1.2 ohm resistor capable of 20 watts heat dissipation.

[polar_explorer]

The bow thruster could be just on or off, but i'd rather have it speed controlled so i can have finer control over it. I did think about using a resistor, but if its speed controlled that won't work. Having it on/off is plan B if i can't get a voltage convertor to work.

[Laurent]

Why don't you get a 7,2 V battery to feed your bow thruster motor? could be cheaper than the Voltage drop option you want to take.

Regards,

Laurent

[Kiwimedic]

Hi
I just get on E-Bay and look for a BEC unit 12v to 7.2 V
Not on every day but they are there regularly.
Last one cost me �7.00 delivered.

Phil