We found this circuit in the November 1992 issue of Radio Electronics magazine. The circuit has two integrated circuits, one of which is a preamplifier stage. The power supply must be dual.
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...