Peripheral driver IC is interfaced with the
microcontroller IC to get the output. Through this IC we
connected three relays, and these relays control the motors.
The NPN transistors connected in Darlington pair fashion
are ideal for interfacing between low logic level digital
circuitry (ATMEL 89C51) and high current/voltage
devices like lamps, relays and other applications in
industrial and consumer fields. The ULN2003 IC is a high
voltage and high current interfacing IC.