Wire a rheostat (two-pole variable resistor) into the circuit between the supply and the motor.
The speed of the motor depends on how much current passes through.
( The Mock TurtIe ™ --- Thinks you are a cunt, on, Fri 28 Jan 2011, 22:33, 1 reply, 15 years ago)

I
thought that too, but the electro-engineer at work told me that the current the motor would draw at that wattage would melt such a thing in no time and that I'd need a PWM instead.
(dchurch bah, Fri 28 Jan 2011, 22:36, Reply)

Hmm, that looks more complicated.
From a few minutes' googling, it seems like your best bet is to use integrated circuits or rig up a simple pulse train in conjunction with a MOSFET. Or a buy a kit.
( The Mock TurtIe ™ --- Thinks you are a cunt, on, Fri 28 Jan 2011, 23:01, Reply)

The
more I google about it, the more confused I get.
(dchurch bah, Fri 28 Jan 2011, 23:10, Reply)

i reckon...
all you'll need is a heavy enough rheostat.
the 100A rating'll be max so 30A may be enough.
( blaireau69 , the Cumbrian Travis Bickle., Fri 28 Jan 2011, 23:11, Reply)

This will just lead to the installation of an electric fire with a small motor attached.

( Bartleby A dead man on vacation, Fri 28 Jan 2011, 23:15, Reply)

isn't that the idea?

( blaireau69 , the Cumbrian Travis Bickle., Fri 28 Jan 2011, 23:18, Reply)

And empty the battery in no time too.
I thought the idea was to control a motor.
( Bartleby A dead man on vacation, Fri 28 Jan 2011, 23:21, Reply)

sorry, i've been feeling flippant all day.
it's been a cunty week.
( blaireau69 , the Cumbrian Travis Bickle., Fri 28 Jan 2011, 23:35, Reply)

What about putting a big resistor before the rheostat and a power transistor after it?

( The Mock TurtIe ™ --- Thinks you are a cunt, on, Fri 28 Jan 2011, 23:30, Reply)

Yeah, something like that.

( Bartleby A dead man on vacation, Fri 28 Jan 2011, 23:32, Reply)