DIY Flashing Safety Light Circuit Using LEDs for Vehicles
During poor visibility, i.e., when there is fog, or at dawn or dusk, or when your vehicle gets stalled on a lonely stretch of...
Auto Muting Circuit During Phone Calls
Telephone conversation can be made disturbance-free using this simple circuit. As soon as you lift the telephone handset to converse, the TV, music system...
DIY Doorbell That Sounds Like a Parrot—No IC Required!
Here is a mains-operated door-bell that produces parrot-like sweet voice without requiring any musical IC. The circuit is cheap and easy to construct. The...
DIY: Replace Fridge Bulb with Energy-Efficient LED Lighting
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,...
DIY Automatic Emergency Light Circuit with Auto Charging Feature
This emergency light has the following two advantages:
1. It turns on automatically when the mains power fails, so you need not search it in...
Simple Automatic Water-Level Controller
Water level controllers are common nowadays. The automatic water level controller described here is built around a timer NE555 and inverter buffer CMOS IC...
Simple High-Sensitivity Temperature Switch
This temperature switch has high sensitivity and is quite reliable. Here, in place of a single transistor, a Darlington pair has been used for...
Connect Two Telephones in Parallel with Intercom Functionality
The circuit presented here can be used for connecting two tele phones in parallel and also as a 2-line intercom.
Usually a single telephone is...
DIY Extra Telephone Ringer with Visual and Audio Alerts
Many a times one needs an extra telephone ringer in an adjoining room to know if there is an incoming call. For example, if...
Build a 1-Second Tone Generator Using UJT for Darkroom or Metronome Use
The timer circuit described here provides a pleasant musical tone in your darkroom at 1-second intervals.The circuit takes up very little space and can...
DIY Electronic Horn Circuit
Here’s a simple circuit of an electronic horn that is built around quadruple op-amp IC LM3900 (IC1). IC LM3900 has four independent op-amps (A1...
CORDLESS PHONE BACKUP
Normally the base of a cordless phone has an adaptor and the handset has Ni-Cd cells for its operation. The base unit becomes inoperative...
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 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...
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...
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....
DIY Telephone Call Meter Using Calculator and Quartz Clock Circuit
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...
Connect Two Telephones in Parallel Without Interference
Often a need arises for connection of two telephone instruments in parallel to one line. But it creates quite a few problems in their...