This circuit triggers a Sonalarme when the LED used as a sensor receives light. The circuit was found in an old documentation, but the components used are all current.
Using a 4046 PLL this circuit recognizes a 1.6 to 1.8 kHz tone by driving an output LED. The...
This battery charger circuit was found in ancient American documentation. The components are...
This circuit is of great use today, when solar energy is becoming increasingly important. The...