March | 2011 | Embedded Lab

Monthly Archives: March 2011

Automate lights in your kitchen area

Posted on March 10, 2011 by R-B 2 comments

This project describes an automatic light system for kitchen sink where you need sufficient light to properly clean your dishes and vegetables. It uses an ATTiny84 microcontroller with a PIR motion sensor. When motion is detected, the microcontroller turns on the light. The light source consists of 10 bright white LEDs that are driven by a IRF612 MOSFET. One advantage of using a microcontroller is you can create light fade-in and fade-out effects using PWM.

555 Contest Entry: Music synthesizer

Posted on March 10, 2011 by R-B One comment

A music synthesizer is Frank’s entry to the 555 contest. He used a 555 timer to make a really cool synthesizer that is played with a stylus and has filtering and volume enveloping features. Various note frequencies are generated with precisely calculated resistances.

Commandments for using PIC Microcontrollers

Posted on March 5, 2011 by R-B Leave a comment

Based on his working experience with PIC microcontrollers, John Chandler has summarized some basic rules that could minimize the project development time and increase the reliability of PIC operation. Some of these rules (he said commandments) are related to power supply, clock and reset operation and hence they are applicable to all PIC circuits. Some PIC microcontrollers have multiple pins for Vcc and ground. He suggests to connect all of them not just one pair. A 0.1 uF bypass capacitor must be connected closest to the microcontroller. Similarly, the MCLR pin must not be floating, if it is enabled. Read more

555 Contest Entry: “Whack a Mole” style game

Posted on March 5, 2011 by R-B One comment

Jim Chen made a very interesting LED chasing game that uses six 556 timer chips. This is his second entry to the 555 contest which is recently closed. There are nine LEDs in the game. Any of them could glow randomly. The player has to turn off the LED by touching an electrode next to the LED. While the player continue playing the game the time available for the player is less and less. When you missed to turn off an LED within the provided time frame, the game is over. Here’s how the game works.

555 Contest Entry: Direct conversion RF receiver for 80 meter amateur band

Posted on March 4, 2011 by R-B Leave a comment

Direct conversion RF receivers are different from the standard superheterodyne one as they don’t have IF stage, and so the radio signals are directly converted into audio signals. This project uses 3 555 timer ICs as the only active devices to construct a direct-conversion radio receiver for the 80 meter amateur radio band.

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