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Machine consciousness
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Ideas for Design: Vol. 1 No. 1

We start out our collection of Electronic Design Ideas for Design with three articles from our 2012 issues. We hope you enjoy them.

Download Ideas for Design: Vol. 1 No. 1 in PDF format.

Contestant Controller Is Simple and Easy to Expand

Game-show "contestant-selection" controllers aren't new. But the designs are complicated, especially as the number of inputs grows. This contestant controller is simple and expands easily. The idea is to keep arbitration to a minimum. The design has a window of opportunity so small (nanoseconds) that if two or more signals get through, you can call it a tie.

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Simple Circuit Turns PWM Into a Digitally Adjustable Precision Reference

Designs frequently require the conversion of a microprocessor's pulse-width-modulation (PWM) signal into an analog voltage. Often a passive single-pole RC filter will satisfy design requirements, but this approach typically suffers from several drawbacks, including slow response time, noisy results, and having an unbuffered output. The circuit uses the ubiquitous LM431 shunt regulator to implement a second-order Sallen-Key low-pass filter together with a level shifter.

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Simple Circuit Offers Single-Adjustment Tone Control

Early radio receivers and record players nearly always had a knob marked "tone," which was usually a crude low-pass filter with some form of severity adjustment. At best, these controls could partially compensate for bass loss caused by poor speaker baffling. More sophisticated controls were developed for more modern equipment, including the bass/treble (Baxandall) controls, parametric equalizers, and graphic equalizers. Nevertheless, a single-adjustment tone control often can be useful for fine balance adjustment or where multiple controls are impractical or unnecessary.

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