74*245 Motor Driver

H-Bridge Driver

Simple PWM Gen.

Handy Method Measuring RPM

Measuring RPM via Photo reflector

Introduction to Robotic

DC, Stepper,and Servo Motor

Microcontroller Tutorial

Computer Interface
Tutorial
.............more links

A 74*245-based motor driver
by : Erric Seale

A simple, time-honored approach is to use one or more 74*245 chips (normally the 74AC245 is used for maximum current capability) to provide motor drive current. Here, each channel of drive power is provided by one or more buffer on the chip.

One of these chips can provide 8 individual drives, at up to 35 mA per channel (at least, this is the official number -- read on, and you'll see you can get a bit more out of this chip...). If you need more current than one driver can provide, you can put drivers in parallel, or stack chips (or both):

Note that the available drive current is a function of both your supply voltage, as well as of the output voltage you can tolerate. Below, I've plotted data I collected from a single 74AC245 chip (YMMV):

Since the 74*245 is a 20-pin chip, it'll require 20 connections / PCB holes.

The 74*245 is a popular choice for providing drive power for 2-motor / 4-legged walkers: