Found in an Analog Devices documentation from the 90s, this circuit uses operational amplifiers from the time. The power supply must be symmetrical.
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...