Wednesday, December 1, 2021

COMPUTERISED MORSE CODE GENERATOR/TRANSMITTER

The circuit given here can be used to send telegraphic messages via computer. The message data entered through the computer keyboard is converted to corresponding Morse code and transmitted via the...

Secret Bell

Many people move through the corridors and steps in multistoried buildings. As most of them are strangers for the inhabitants of the flats, it becomes necessary to verify the identity of...

Ultrasonic Proximity Detector

We the humans can hear sound of up to 20kHz frequency only. This proximity detector works at a frequency of 40 kHz. It uses two specially made ultrasonic transducers: One transducer...
PC Power Manager

PC Power Manager

Very often we forget to switch off the connected peripherals like monitor, scanner and printer while switching off our PC. This leads to needless energy consumption and possible shortening of the...

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 cash box that thwarts the theft attempt...

TELEPHONE CALL METER USING CALCULATOR AND COB

In this circuit, a simple calculator, in conjunction with a COB (chip-onboard) from an analogue quartz clock, is used to make a telephone call meter. The calculator enables conversion of STD/...

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...

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...

LED Illumination for Refrigerators

The incandescent lamp provided inside the refrigerators glows whenever we open the door. It suffers from several disadvantages like: 1. Being a single light source, located in the upper corner, light does...

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 comes handy in such a situation. It...
 
 
 

What's New @ Electronicsforu.com

Most Popular DIYs

Electronics Components

Testing Times

Design Guides

Truly Innovative Tech