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...
Build a Crystal-Controlled 12 MHz AM Transmitter Without LC Tuning
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...
Build an Automatic Fan Speed Controller with 555
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...
Dual Priority Encoder Circuit Using
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...
UPS FOR CORDLESS TELEPHONES
Cordless telephones are very popular nowadays. But they have a major drawback, i.e. they cannot be operated during power failure. Therefore usually another ordinary...
Telephone Security Circuit to Prevent Unauthorised Line Use
Most of the telephone security devices available in market are simple but quite expensive. These devices provide blinking or beeping type line-tap misuse indications....