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...
CLAP SWITCH
Here’s a clap switch free from false triggering. To turn on/off any appliance, you just have to clap twice. The circuit changes its output...
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 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...