Mechanical and Electromechanical Systems

Understanding Mixed Decay and the Allegro A3977 PFD Percent Fast Decay Feature

Posted: April 16th, 2009 | Author: Tom Scarince | Filed under: Stepper Motors | Tags: | No Comments »

This article explains why you might want to use mixed decay and how it is implemented in the A3977’s current chopper PWM scheme with the percent fast decay (PFD) pin. 

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Bidirectional PWM Motor Control

Posted: April 7th, 2009 | Author: Tom Scarince | Filed under: Motor Control | No Comments »

Once you understand unidirectional PWM of an inductive motor load, we can expand the concept to a bidirectional h-bridge PWM circuit.  Read the rest of this entry »


Unidirectional PWM Motor Control

Posted: April 2nd, 2009 | Author: Tom Scarince | Filed under: Motor Control | No Comments »

This article covers unidirectional Pulse Width Modulation (PWM) and how it can be used to control the power applied to a DC motor or the current in a stepper motor winding, for instance. While we eventually want to talk about doing bidirectional PWM with an h-bridge, we’ll start with a simple, one-direction control circuit.

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Intro to H-Bridge Motor Control Circuits

Posted: March 26th, 2009 | Author: Tom Scarince | Filed under: Motor Control | No Comments »

Simplified H-Bridge

An h-bridge is a bipolar driver circuit that is often used to control a load such as a brush type DC motor.  This article covers the most basic concepts of a simplified h-bridge circuit. Later articles dig deeper into the details of practical h-bridge operation and design.

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Stepper Motor Wiring Options

Posted: March 19th, 2009 | Author: Tom Scarince | Filed under: Stepper Motors | No Comments »

Stepper motors may come with four, five, six or eight wires. This article will help you identify the correct way to wire an unknown stepper motor. Read the rest of this entry »