DIAC Controlled Flasher
This simple flasher finds various industrial applications as a high-voltage indicator or machine-’on’ indicator. It flashes once every second to give a warning indication. It is simple to design and can be wired lead-to-lead without using PCB.
Audible Continuity Tester
Here is a pretty simple, low-cost audible continuity tester that makes use of just one quad comparator IC LM339, some resistors and a piezobuzzer. The circuit including the comparator works off a single 9V battery.
Audible IR Proximity Detector
This circuit gives an audible indication when any object comes in front of the infrared reflecting sensor (containing IR LED and phototransistor). The sound generated by the sensor will be louder if the object close to the reflecting sensor is opaque.
White LED Based Emergency Lamp and Turning Indicator
White LEDs are replacing the conventional incandescent and fluorescent bulbs due to their high power efficiency and low operating voltage. These can be utilised...
IR Receiver Module Tester
Here is an IR receiver module tester for on-board testing of IR modules used for remote control of TV sets and VCD players. The...
IR Music Transmitter and Receiver
This IR music transmitter and receiver contains two circuits - one transmitter and one receiver. The transmitter transmits musical tones through an IR LED and the receiver receives those signals through a photo transistor.
House Security System
This is a circuit for a home security system that sets off an alarm when someone interrupts a laser beam that continuously falls on LDR of the circuit. A combination of 6 plain mirrors is used to direct the laser beam around the house to form a net.
Numeric Display Digital Dice
This is a circuit for a digital dice with numeric display that generates random numbers from 1 to 6 and displays them on a 7-segment LCD. The circuit can be modified to increase the range from 1 to 9.
Appliance Timer cum Clap Switch
This is a circuit for an appliance timer cum clap switch that can operate devices with a clap or can switch them on/off by setting an advance timer ranging from one second to 100 hours in advance.
Panic Button
Useful for the elderly and ailing persons, this touch-sensitive panic button circuit sounds a panic alarm to catch the attention of others for immediate...
A Multipurpose Listening Device
This multipurpose listening device can detect very faint, remote sounds with a good clarity. It is useful in large conference halls, auditoria, cinema halls,...
Hidden Alarm Switch
This simple hidden alarm switch produces a warning beep when somebody crosses a protected area in your home or office. The switch, hidden below...
Infrared Electronic Shooting Game
This is a circuit for an infrared electronic shooting game that consists of an IR gun and a target board. It consists of eight red LEDs and a green LED. Green LED lights up when a hit is made at the infrared receiver module and a buzzer sounds.
Touch Sensitive Musical Bell with Timer
Recently musical doorbells have become very common. Musical and continuous power doorbells serve as an attempt to bridge the gap between newer digital circuitry...
Photodiode Based Fire Detector
This ultra-sensitive photodiode based fire detector protects your electronic devices like computer and television set. It uses a photodiode as the fire sensor and...
Audio Controlled Running Light
This mains operated audio controlled running light can be used in discotheques. The lamps glow in running sequence as per the sound of music....
Melody Generator With Instrumental Effect
This is a circuit for a melody generator that can provide various modes of melodies along with instrumental effect that can be chosen through dip switches.
PC Temperature Controller
Here is a simple temperature controller that turns your personnel computer (PC) off when the temperature of the PC increases beyond the optimal temperature value. Some of the larger integrated circuits become quite hot and if the temperature inside the PC