Wiring a DC motor for variable speed control

I am wiring up an electric motor from a drill. The catch is that I cannot use the switch with which it came. It is a 9.6v drill motor, and I want to be able to vary the speed with two potentiometers. Also, if at all possible, I would like to use a 24 volt battery. If more info is needed please ask. Thanks for your input. Craig Cordill

I am wiring up an electric motor from a drill. The catch is that I cannot use the switch with which it came. It is a 9.6v drill motor, and I want to be able to vary the speed with two potentiometers. Also, if at all possible, I would like to use a 24 volt battery. If more info is needed please ask. Thanks for your input. Craig Cordill

Why 2 potentiometers? One varies the speed - what does the other do?

Here is a circuit diagram for one:

This will run at 24v but you will have to put a 7.5v zener in series with the supply to the electronics. It's max voltage is 18v.

With a bigger heatsink, or forced cooling, you could run to 12A or so - over 100W of motor power.