This tiny circuit can protect your Locker or Almirah from a burglary. If the locker opens in the armed state, the circuit generates a loud police siren to thwart the attempt of burglary. The siren stops only when the locker door closes again. The circuit is too compact and can be powered by 3 volt…

 You can use this Simple Alarm to protect the door or Window. It gives a loud beep and switch on the room light when an intruder/burglar attempts to breaks the door lock. The alarm functions only after 5 minutes to confuse the intruder.   Working of this burglar alarm circuit is simple. IC1 is used…

 This light triggered circuit can be used to turn on / off a load such as lamp through the IR rays from a remote or light from a torch. This is an ideal circuit to switch on / off the room light using TV remote while watching the TV .The circuit uses a Phototransistor and…

 Here is a low cost Surge protector circuit for Electric appliances, TV, Computer etc from high voltage spikes that appear in the power lines. Very high voltage spikes and transients develop momentarily in the supply lines when lighting occurs. Such short duration high voltage spikes also super impose on the mains when high current loads…

Here is a simple Music Bell with In and Out indicator. The bell as well as the display turns on for 2 minutes and stop automatically. The circuit uses the popular ROM IC UM66 to generate music tone and a common cathode 7 segment display to show In or Out.   IC1 (NE555) is wired…

 Sleep is the physiological process by which body gets sufficient rest to rejuvenate the cells including the brain cells. It is actually a shift in brain’s activities to slow the basic bodily functions. This shift in the brain’s activity is accompanied by a major shift in the consciousness.   Science of Sleep Sleep can be…

 Here is a simple circuit to protect TV from high voltage spikes during lightning or a power surge in the cable. It can be incorporated in the Coaxial cable of TV Antenna or Set top box. It uses a GDT and Safety capacitor to provide protection from high voltage spikes. The same circuit can also…

You can fix this circuit in the switch board that provides power to the loads such as Water heater, Electric Iron etc to remind you that the load is switched on. LED blinks indicating the load on status and the buzzer beeps every 30 minutes. This helps to prevent the wastage of energy usually happens…

Save your spare batteries from self discharge due to improper charge- discharge cycles. If you forget to charge the sealed lead acid battery for long period, it will not accept full charge during charging and its performance deteriorates. A solar panel can solve the problem and since it charges only during day time, over charging…

 Colour is the visual perception of different wavelengths of light such as red, green etc. Colour derives from the spectrum of visible light which interact with the colour sensitive cells of the retina to give the colour vision. Colour may be defined or quantified based on the degree by which the various colour sensitive cells are stimulated. The science of color is…

Some Microcontroller based Laboratory instruments such as Digital balance, pH Meter etc have rechargeable battery inside. This inbuilt battery should be properly charged for the error free operation of these instruments. If the instrument is not using (or charging) for long time, its inbuilt battery will be destroyed permanently. This charger timer circuit helps to keep…

 Here is a simple but useful battery level indicator to monitor the battery terminal voltage. Efficiency of the battery reflects in its terminal voltage. A good Lead Acid battery will show 13.8 volts in the fully charged state and if it is below 10 volts, the battery needs immediate charging. If the battery voltage goes…

This circuit can sense the overload condition and breaks the power if the load increases above the set point. It is an ideal circuit to protect Uninterrupted Power Supply devices like Inverter.Let us see its working …The Optocoupler MCT2E and the Resistor R3 (1 Ohm 10 Watts) will do the trick. The Optocoupler has an LED and a Phototransistor inside with connecting leads. The LED of MCT2E is connected parallel to the resistor R3 with a current limiter R2 for the LED. The phototransistor of Optocoupler is connected to the transformer derived 9 volt DC through the current limiter R1. The load is connected through the Common and NC contacts of the relay. So it will work normally at power on. 

Here is a dual colour lamp to read the code printed on the Transistors and ICs. The code and number printed on the black coloured body of these components are difficult to read if the room light is low since the printing is in faint colour or as impressions. This LED lamp is useful to…

Interactive white board is an interactive display device that displays the computer screen that can be controlled using the electronic pen. It is also known as Smart Board. A projector, projects the computer screen on to the interactive board so that the user can control the PC by touching the surface of the board. It…

 UM 3561 is an excellent Siren generator IC widely used in Toy applications and Surveillance systems to generate different tones. It a ROM (Read Only Memory) IC which can be operated in 2 pen cells and it functions normally down to 2.4 volts. Using only a few components, it is very easy to construct a…

In contrast to the ordinary TV, Digital TV or DTV uses the transmission in Digital format. Digital TV supports various types of picture formats of different combination size and interlacing. The digital format may be High Definition TV (HDTV) or Standard Definition TV (SDTV). HDTV transmission is in p720 (720 Progressive scanning) or i1080 (1080…