This circuit was published in the July 1993 issue of Electronics Now magazine. It uses a sensor from the time and triggers a buzzer with a Sonalert-type oscillator.
Using a 4046 PLL this circuit generates rectangular signals in three wavebands that depend on the...
This circuit is from the LM3914 manual and can be found elsewhere on this site and from other...
The circuit used is the 4093 configured as an inverter in this application from Radio Electronics from...