If the battery is good, the LED flashes. This simple tester uses an LM3909 integrated circuit. We found this configuration in an old documentation.
This series and parallel sensor circuit was found in Popular Electronics from the 1990s. Any SCR...
This circuit is based on an MC1408, an integrated circuit that is not common today. The...
This power supply for gas laser (HeNe) was found in a 90’s Popular Electronics. It generates from 1300...