Dc Motor

Jlittlemyer

I am currrently working on my first project, an autonamous car. I am salvaging an old R/C car that the circuit shorted out..·I checked the motors under a load and they drew nearly·500ma.·Can someone please help me figure out a way to drive the motors without burning up the BS2?·Thanks in advance.··

RoboticsProfessor

Google H-Bridge motor driver.

An h-bridge is a circuit that lets you use a digital, low voltage signal to control the speed and direction of a motor. The designs you will see mainly focus on the max current draw, and yours is small, so smaller/cheaper/simpler will do fine. Reading the current while forcing the motor to stop while you are trying to drive it will give stall current,·a worst case current draw situation. Have your h-bridge be rated at a little better than that. I would also guess that an h-bridge rated at 1 amp would give you a comfortable safety factor. You need one h-bridge circuit for each motor.

You have two general choices:

1. Look for designs and schematics and build your own, or

2. Many manufacturers make dual h-bridge driver circuits you can purchase for a reasonable price.

My students have done both.·Mostly it depends on if you like to build things from scratch or not.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Richard Vannoy

Programming and Electronics Instructor
www.RichardVannoy.info
·

Jlittlemyer

Thanks for the info. I had planned on using an H bridge but I have never built one. I went today to the local radio shack and electronics store but they never have the components needed. I ended up finding two NPN Darlington transistors but im out of luck with the PNP darlington's. I guess Ill be ordering offline and waiting for the shipment.

LilDi

Take a look at the 754410 IC. Its a quad H-Bridg. It is rated at 1 amp, but two of these ICs can be stacked on top of one another for 2 amps.

http://www.makingthings.com/resources/datasheets/SN754410NE_slrs007b.pdf

http://www.acroname.com/robotics/info/ideas/stacking/stacking.html