Archive for February 2010

A Parallel Port Stepper Motor Driver With Discrete Components

Using PC’s parallel port is a convenient way to control a stepper motor. For unipolar stepper motors, up to two motors can be controlled with the 8bit data line. Continue reading ‘A Parallel Port Stepper Motor Driver With Discrete Components’ »

An Isolated MOSFET Serial Port Relay Controller

Using DTR (data terminal ready) and RTS (request to send) pins of a PC serial port (RS-232) without actually using the serial data pins, we can interface at least two relay devices with a computer. Windmeadow Labs has an excellent article on how to achieve this using a bipolar transistor (BJT). Here I will show you a similar relay control circuit built using an opto-isolator and a MOSFET. Continue reading ‘An Isolated MOSFET Serial Port Relay Controller’ »