Miniature Strobe Light
Strobe lights are widely used by disco lovers to create wonderful visual effects in disco halls and auditoria. The circuit of a battery operated...
Mobile Theft Alarm
This circuit works as a mobile anti-theft system. It produces a loud chirping sound whenever someone tries to take away the mobile and also works as a mobile charger.
Aquatic Probe
A number of environmental factors including light and temperature affect fish culture. The temperature of water has profound effect because fish cannot breed above...
Liquid Level Alarm
In water-level controllers for tanks, a DC current is passed through the metallic probes fitted in the water tank to sense the water level....
Electronic Dog Whistle
A dog whistle is a type of whistle that emits sound in the ultrasonic range, which people cannot hear but some other animals can,...
Acoustic/Mechanical Vibration Sensor
This circuit contains a piezoelement that detects any vibrations in the shutter of a shop and activates a lamp and a police tone alarm signal.
Desktop Power Supply
Useful for electronics hobbyists, this linear workbench/ desktop power supply converts a high input voltage (12V) from the SMPS of a PC into low...
Inexpensive Car Protection Unit
For car protection, custom made units are available but they are costly. Here’s an inexpensive car protection unit to protect car stereo, etc. from...
Doorbell cum Visitor Indicator
This doorbell cum visitor indicator circuit can also give identification of the visitor to your home in your absence. When you’re home, you can...
PC Temperature Alarm
This circuit uses a temperature sensor to detect the temperature inside the PC and generates an alarm if the temperature exceeds a pre-set limit.
Automatic Lighting Fence
This circuit can sense the movement of a person within the range of three metres from a fence and produce a tone from the buzzer. This is used as a security system.
Automatic Off Timer For CD Players
This is a circuit that initiates a timer for turning off CD player as soon as the bedroom light is turned off.
Electronic Door Key
This circuit is basically a short-range, infrared remote-controlled electromagnetic relay driver. It can be used to control door motors or solenoid-based locks using a compact and handy remote handset.
Light Operated Doorbell
Light-dependent switches are used in automatic hand-dryers and flushers in toilets. Here is a simple light-operated switch that works in normal light also. You can affix it on the main door of your house to work as an automatic doorbell or a thief alarm.
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...