SMART PHONE LIGHT
The circuit shown here is used to switch on a lamp when the telephone rings, provided that the ambient light is insufficient.
The circuit can...
CLAP REMOTE
An infra-red or wireless remote control has the disadvantage that the small, handy, remote (transmitter) is often misplaced. The sound operated switch has the...
CD-ROM DRIVE AS DIGITAL AUDIO CD-PLAYER
ACD-ROM drive can be used as a stand-alone unit for playing digital audio CDs without interfacing with a computer. The stereo output of CD...
SHORT WAVE AM TRANSMITTER
The main feature of this transmitter is that it is free from the LC (inductor, capacitor) tuned circuit and operates on a fixed frequency...
SOLID STATE AUTO POWER-OFF ON MAINS FAILURE
A good number of circuits which turn off the power to the load on mains failure have already appeared in EFY. This circuit is...
AUTOMATIC SPEED-CONTROLLER FOR FANS AND COOLERS
During summer nights, the temperature is initially quite high. As time passes, the temperature starts dropping. Also, after a person falls asleep, the metabolic...
FREQUENCY MEASUREMENTS USING PC
PROBIR GOYAL
Here is a simple technique for measuring frequencies over quite a wide frequency range and with acceptable accuracy limits using a PC. It...
A Hierarchial Priority Encoder
Anormal priority encoder encodes only the highest-order data line. But in many situations, not only the highest but the second-highest priority information is also...
DIGITAL SWITCHING SYSTEM
This circuit can control any one out of 16 devices with the help of two push-to-on switches. An up/down counter acts as a master-controller...
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...
