This solidstate signal lamp is a good alternative to revolving mechanical signaling lamps used in ambulances. It uses ultra-bright blue LEDs for signaling. However,...
This parallel telephone circuit provides secrecy when two or more telephones are connected in parallel to a telephone line. The circuit also prevents incoming...
The circuit automatically disconnects power supply to the audio/video system whenever the mobile handset is lifted off the holder for making or receiving a call.
Burglar alarms have become standard equipment in stores and other businesses, and they're becoming increasingly common in private homes as well. If you've ever...
At night, parking lights make your parked car visible to motorists so they don’t smash into your car. However, these lights drain considerable power...
This simple intercom circuit functions quite satisfactorily. The circuit does not involve any complicated switching. The switches S1/S2 must be fixed in such a...