Power Suppy Failure Alarm
The power supply failure alarm circuit presented here needs no additional supply source as it employs an electrolytic capacitor to store adequate charge...
Experimental Study of Switched Capacitor Circuit
In recent years switched capacitor circuit has gained popularity due to their suitability in integrated circuits.
The two major problems faced by IC designers are:
1....
Dual Audio Signal Tracer
The circuit described here is of a dual audio signal tracer. An audio signal tracer is a simple device used to troubleshoot for audio...
Automatic Bathroom Light with Back-up Lamp
Sometimes we forget to switch off the bathroom light and it remains on unnoticed for long periods. This automatic bathroom light circuit solves the...
Mains Supply Failure Alarm
When ever AC mains supply fails, this mains supply failure alarm circuit alerts you by sounding an alarm. It also provides a backup light...
Manual EPROM Programmer
The programmer devices required for programming the electrically programmable read only memories (EPROMs) are generally expensive. Here is a low-cost EPROM programmer circuit to...
Wireless Stepper Motor Controller
Here is a low-cost and simple wireless stepper motor controller using infrared signals. Using this circuit you can control the stepper motor from a...
Digital Frequency Comparator
Here’s a digital frequency comparator for oscillators that indicates the result through a 7-segment display and a light-emitting diode (LED). When the frequency count...
Microcontroller Projects: RGB Colour Generator
Presented here is a red, green and blue or RGB colour generator using AT89C2051 microcontroller (MCU). This is a simple and low-cost circuit for...
Smart Foot Switch
This is a circuit that can be used to switch on and off two devices alternatively or both together by using switches. Two switches are for each device to turn them on and switching off other device, also it has a separate switch with an option to turn on both the devices simultaniously.
Automatic Soldering Iron Switch
Soldering irons are most often used for installation, repairs, and limited production work in electronics assembly. High-volume production lines use other soldering methods. You...
Programmable Timer for Appliances
This is a circuit for a programmable timer that can be used to switch on/off a device after a pre-set time period that can be varied from 8 seconds to 2 hours. It works in two modes, cyclic mode and off mode that can be switched by using a slide switch.
Multiband Transmitter
A radio frequency oscillator is at the heart of all radio transmitters and receivers. It generates high frequency oscillations, which are known as carrier...
Versatile LED Display
This versatile LED display circuit uses an erasable programmable read-only memory (EPROM) to display various light patterns on LEDs. Since bicolour LEDs (comprising green...
Sound Operated Intruder Alarm
When this sound operated intruder alarm detects any sound, such as that created by opening of a door or inserting a key into the...
Soldering Iron Temperature Controller
When soldering, sometimes the need arises to control the temperature of the soldering iron. It is not possible to change the solder iron every...
Electrolytic Capacitor Tester
Using this electrolytic capacitor tester you can detect leaky and dead (open) electrolytic capacitors. It operates based on the time constant (T) of the...
Digital Mains Voltage Indicator
This is a circuit for a digital mains voltage indicator that displays main voltage in the form of a LED bar graph with 16 LEDs. The first LED indicates voltage level at 50 V and the 16th LED shows voltage level for 280 V.