Can I use relays for motor control?

I'm making an Arduino sumo robot, and the Arduino can't give enough current to the motors.  I don't want to have to buy anything while making this.  I was wondering if I could have the Arduino activate 5 volt relays and then have the relays activate the motors, which eould have their own power supply.  If that's not possible, tell me some way that I can just use a few transistors or whatever (but no ICs).

frollard4 years ago
You can use relays but they aren't very good at variable speed generated with PWM - because it involves pulsing the power VERY quickly (100-1000Hz) and relays don't like being pulsed.

What I would recommend is building a motor driver, or better yet, pick up an arduino Motor Shield. It has special transistors called MOSFETS - they work like relays but have no moving parts - relying on just semiconductor to switch big loads with little arduino pins.