The ZN416E integrated circuit is uncommon today. It consists of a complete radio, like the one found in a 90s Popular Electronics. The power is from a single battery.
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...