Mechanical and Electromechanical Systems

Frosts Mora Swedish Knives Clipper vs. Craftsman Comparison

Posted: April 23rd, 2009 | Author: Tom Scarince | Filed under: Uncategorized | No Comments »

The town of Mora in Sweden is known for its traditional and utilitarian fixed-blade knives.  Many survival and bushcraft experts recommend these simple and very inexpensive knives, especially for beginners.  This article was originally posted by me on the Equipped to Survive Survival Forum.     

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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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