Circuit Cellar Ink 215
June 2008

Table of Contents


CJ Abate

HTML Task Manager

Communications Hub


John Gorsky

New Product News


Peter Csaszar
Monica Flores

Message Acquisition

Ring Signal Detection And Interpretation

You'll never miss another voicemail message with Peter and Monica's voicemail monitoring system. Their device monitors the signal from an analog phone line, analyzes it, tracks the number of calls and messages, and displays the number on a VFD.



Richard Wotiz

Pump Control

Build A Variable-Speed Drive For Motors

Richard's single-phase, variable-speed drive for AC induction motors is an excellent device for powerful, yet quiet, pump operation. Designed for use with a capacitor-start/capacitor-run motor, it includes active power factor correction (PFC) and inrush current limiting.


Above the Ground Plane


Ed Nisley

Resistance Soldering

In his last two columns, Ed discussed transformer action and the simulated triac control of an inductive load. This month, he describes a real-world application: circuitry connected directly to an AC power line.



Scott Bingham
Yunfan Donald Zhang

Ray Tracing Made Simple

A Ray Tracer Implemented On An FPGA

Scott and Yunfan implemented a ray tracer on an FPGA. The ray tracer can draw spheres and planes with reflections, shadows, Lambertian lighting, patterns on planes, and antialiasing.



Peter Baston

AIS Transmission Decoding

Peter created a system that receives and decodes data transmissions from ships and other vessels via the Universal Automatic Identification System. Built around a Luminary Micro LM3S811 evaluation board, the decoder displays a "virtual" radar screen, showing the position of vessels in the area.



Andrew March

MCU-Based Game System

A Dot-Matrix Game That Targets C Coding Efficiency

Andrew built a hand-held, dot-matrix video game that features scrolling scores and sound effects. You can implement an Atmel AT90S2313 and the C programming language to build a similar system. This project proves that you can use a modern CPU architecture and an efficient compiler to produce compact code without having to resort to assembly language to achieve your desired functionality.


From the Bench


Jeff Bachiochi

Self-Destructive Behavior

Processor Action Requires Power Supply Removal

Fed up with corrosion? Eliminate the contacts. Jeff replaced his old doorbell switch with a capacitive touch pad using only the pair of wires available at the door. If you are not in the market for a new doorbell, this solution could work well in a different project.


The Darker Side


Robert Lacoste

Let's Be Crystal Clear

Many electronic devices are enhanced by crystals, but do you know why? Robert explains why there are usually small capacitors around a crystal, the difference between "series" and "parallel" crystals, and more.

Silicon Update


Tom Cantrell

Touch Me

If you haven't used touch sensors in your designs, you will soon. Tom explores the new touch sensors from Cypress Semiconductor and Silicon Laboratories. Traditional keypads and touchscreens beware!


Crossword Puzzle


Advertiser's Index / July Preview


Steve Ciarcia

HTML Priority Interrupt

It's All In The Whiskers

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