This circuit is for traditional old-style telephone lines found in an American 1980s documentation. Components are common and the optical coupler can be replaced with an equivalent.
This filter can be used to eliminate hum in sound equipment. Operational amplifiers can be 741 and...
Found in 90’s English documentation, this rising and falling siren, manually activated, drives a...
This sensor works as an electronic push button, activating a power relay. The circuit must be...