Variable Amperage in DC Circuit. How?

[Jordan A.]

see title, how do you vary the amperage in a DC circuit?

Thanks.

-Jordan

[jon]

I'm not claiming this is at all right, I am by no means an expert in this area... yet... but, it could be right, maybe, if I'm lucky. Someone let me know if it is and i'll be happy.

Knowing that....

I= E/R

I = current (amps)
E = electromotive force (volts)
R = resistance (ohms)

...couldn't some variable resistors do the trick?

Jon basically said it with varying R (resistance) in the ohms law V= IR....

Other info

heavier wires = less resistance = higher current carrying capability. The inverse is true as well, lighter wires = more resistance = less current carrying capability

Ya so that should sum it up

(Thanks to Rich from 93 for the clairification)

[Al Skierkiewicz]

There are many answers to this question. The speed controllers do this very effectively by rapidly turning the supply voltage on and off. The effect is the average current changes. As Ohm's Law is stated above, if the voltage remains constant then adding or subtracting resistance changes the current. If the resistance stays constant, then changing the voltage will change current. Either method can be accomplished with switching (switch resistors in or out, battery cells in or out.) or variable voltage source or resistor. In many of the motors supplied for our use, the resistance of a few feet of wire can be almost equal to the internal resistance of the motor. Whenever the resistance of the wiring equals the internal resistance of the motor, by Ohm's Law only half of the available voltage will be delivered to the motor.

[kmcclary]

Originally posted by Jordan A.
see title, how do you vary the amperage in a DC circuit?

Thanks.

-Jordan

Please define your intent. Are you asking:
- "How do I control a load?" (a control question), or
- "How do I increase the maximum amperage capacity of a circuit?" (a wire gauge question)


- Keith