Pull-Pin Security Alarm
Here is a simple and low-cost circuit of pull-pin security alarm. While travelling, rig the alarm unit to your luggage using a home-made security...
Electronic Electroscope
An electroscope is the instrument used to detect charged bodies. Here is an electronic version of the scope that is sensitive and, unlike conventional...
LASER-BASED INTRUDER ALARM
You can use this laser-based intruder alarm conveniently at the entrance of a hall or any other similar location to protect the same from...
AC MAINS BISTABLE SWITCH
This AC mains-operated bistable switch turns on or turns off a device using a miniature neon lamp and a few discrete components. This switch...
MOTOR CONTROL THROUGH PWM
Motion control plays a vital role in industrial automation. It is required in manufacturing plants of industries like chemical, pharmaceutical, plastic and textile. And...
Call Bell With Welcome Indication
Here is a simple call bell circuit that displays a welcome message when somebody presses the call bell switch momentarily. The alphanumeric display can...
CASH BOX GUARD
Most thefts happen after midnight when people enter the second phase of sleep called 'paradoxical sleep.' Here is a smart security circuit for your...
GUITAR EFFECT PEDAL POWER
A friend of mine plays guitar with several guitar effect pedals. He had a problem with battery eliminators and cables of the pedals cluttering...
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...
Keep Away NI-CD From Memory Effect
Ni-Cd batteries suffer from an undesirable memory effect due to partial discharge. The remedy is to completely discharge the battery before recharging.
A simple resistor...
IR-Controlled Water Supply
This circuit can be used in homes or small restaurants for any type of water supply unit, such as toilet flush or washbasin tap.
The...
ELECTRIC GUITAR PREAMPLIFIER
Here is the circuit of a guitar preamplifier that would accept any standard guitar pickup. It is also versatile in that it has two...
Simple Key-Hole Lighting Device
When opening the door of your room in the dark, you may have to spend a few minutes searching for the key-hole. Here is...
Halogen lamp Saver For Bikes
Halogen lamps are prone to burn-out owing to their low cold current. The rapid heating inside the lamp melts the thin filament and cuts...
Twi-light using white LEDs
This sunlight-controlled lamp uses a light-dependent resistor (LDR) as the sunlight sensor and a total of 25 high-brightness white LEDs. Separate resistors are connected...
Timer for Mosquito Destroyer
In electric-heating mosquito repellents, an electric vaporiser heats up a mat or liquid to release non-degrading chemicals into the air and keep the mosquitoes...
Pushbutton Control For Single-Phase Appliances
This circuit lets you switch off and switch on a single-phase appliance using two separate push switches. Such an arrangement is common for industrial...
Doorbell-controlled Security Switch
One way to check whether anybody is at home is to ring the doorbell. Burglars too use this very technique. The circuit described here...