Transistor Polarity Checker
Presented here is a simple circuit that will help you figure out whether a transistor is npn or pnp type. If the transistor under...
Demo Circuit for Over-Voltage Protection
Over-voltage protection circuits are used to protect voltage-sensitive loads. Voltage transients may occur due to a number of reasons such as transformer switching, load...
Propeller Message Display with Temperature Indicator
Here we describe a microcontroller-based propeller display that displays any message sent to it via hyper-terminal of a personal computer. Moreover, a temperature sensing...
Dual Motor Control for Robots
Presented here is a simple circuit that can drive two motors for a small robot, allowing the robot to negotiate an obstacle course. Two...
Stop Clock With Battery Backup
Stop clock is widely used in various fields to measure the timing of events. Science laboratory experiments, such as measurement of discharge rate of...
EEPROM Interface for Beginners
Electronic systems today incorporate a number of peripheral ICs that have to communicate with each other and the outside world. To maximise hardware efficiency...
Semiconductor Relay for Automotive Applications
Semiconductor relays provide the same function as electromechanical relays but have no moving parts, which increases their long-term reliability. These relays provide an array...
Part 1 of 3: USING AVR MICROCONTROLLERS FOR PROJECTS
The AVR 8535 microcontroller and its new version ATmega8535 are versatile, high-performance but low-cost chips. This article series covers typical applications of this processor...
Electronic Circuit Prototyping More Than Just An Artefact
Certain doubts in the design of an electronic product can be cleared by building and studying a prototype first. Here we discuss the challenges...
Dummy Load for Amplifier Testing
If you want to test an audio amplifier, here is a compact fan-cooled dummy load that can be used to provide any of the...
Multifunction Power Supply
Many embedded systems these days need +5V power supply with some special functions such as power-fail detection, zero-crossing signals for mains power supply and...
GSM-based Dot-Matrix Display
Nowadays, LED message displays are becoming very popular for transmitting information to large groups of people quickly. These can be used indoors or outdoors,...
Simple Antenna Preamplifier for AM Radios
AM radios are still used for capturing transmissions from long distances (DX reception). But AM radios normally require long (10-30m) outdoor antennae. That is...
Part 2 of 3: Using AVR Microcontroller for Projects
In the first part of this article, we had described the main features of the AVR microcontroller and the hardware/software required for an AT-PROG...
Soldering Iron Tip preserver
Although 60/40 solders melt at about 200°C, the tip temperature of a soldering iron should be about 370°C. This is necessary to make a...
Standalone GPS Receiver with LCD Display
This AVR microcontroller-based global positioning system (GPS) receiver can be used to find the exact location of a place and know its standard time....
Put your own Smiley on GLCD
The regular 16×2 LCD can display characters of only certain dimensions. A graphical LCD (GLCD), on the other hand, can display custom graphics. GLCDs...
Calling Bell Using an Intercom
Here is a simple calling bell circuit that can be used in small offices to call the office boy using an existing intercom system....