DIY Bi-Colour LED Dancing Light Circuit with 555 Timer
The circuit as shown in the figure employs 14 bi-colour (red and green) LEDs having three terminals each. Different dancing colour patterns are produced...
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...
SONG NUMBER DISPLAY
Here’s a circuit to display the song number in an audio system for quick reference to songs. It also serves the purpose of an...
Build a DIY Electronic Lock System with Punched Cards and Relays
The circuit presented here can be used as a lock for important electronic/electrical appliances.
When card is inserted inside its mechanism, depending upon the position...
Build a 1-Second Tone Generator Using UJT for Darkroom or Metronome...
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...
Teleremote Control
Here is a teleremote circuit which enables switching ‘on’ and ‘off’ of appliances through telephone lines. It can be used to switch appliances from...
SLEEP SWITCH CUM WAKE TIMER
Here is a sleep-switch circuit that can be easily converted into a wake-up timer. A dual-mode time setting makes the system versatile. The circuit...
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...
PRECISION DIGITAL AC POWER CONTROLLER
Triacs and SCRs are extensively used in modern electronic power controllers—in which power is controlled by means of phase-angle variation of the conduction period....