Telephone Sentry

It is quite common to find extension phones in homes these days but this kind of convenience also comes with a distinct disadvantage: the possibility of another person listening in. This...

Night Lamp From Scrap CFL

Compact fluorescent lamps (CFLs) are available in different shapes and power ratings. These consist of an electronic ballast circuit and a programmable-logic-controlled tubelight. Most CFL manufacturers offer a guarantee of half...

Versatile DC-DC Converter

Here is a versatile power coupler that connects a device to 5V-19V DC generated from AC mains by a power adaptor. Power adaptors come in different voltage outputs like 5V (for...

Door Alert

This circuit can be operated by any kind of switch. For example, it can be used in a shop to warn that a customer is waiting, with a micro-switch attached to...

Over-Temperature Alarm

This circuit can be used as a warning device which triggers an alarm whenever the temperature exceeds a preset level. It can also be used as a door-alert or general warning...

FLASHER FOR DEEPAWALI

Here is the circuit for a portable electric lamp-cum-LED flasher. It uses a 25W, 230V AC bulb and nine LEDs. When the bulb glows all the LEDs remain 'off, 'and when...

CAR ANTI-THEFT GUARD

Here is an easy-to-build car anti-theft guard. The circuit, shown in Fig. 1, is simple and easy to understand. When key-operated switch S2 of the car is turned on, 12V DC...

Night Lamps

Here are two night lamp circuits using LEDs. One could be used as a night-vision clock and the other as a TV lamp. Both the circuits are AC operated and consume...

Temperature Monitor for Electronic Equipment

As most electronics components’ characteristics vary with temperature, they are selected as per expected operating temperature range of the equipment. So it is important that the equipment stays within the temperature...

Multicolour Curtain Backlights

This circuit comprises two parts: a string of 5mm high-intensity white LEDs connected in series and the circuit wired around. IC CD4060 with an inbuilt oscillator. The IC is wired such...
 
 

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