This unusual circuit from a Popular Electronics of the 90s uses LED indicators, operating as a bridge. The components used are common. It is based on the tuning of the signal by a PLL.
Found in an Electronic Design from the 80's, this circuit uses components from that time. The...
This circuit was suggested by an Electronic Design from the 90s. Its purpose is to detect...
This circuit was found in Italian magazine (1988), but can be mounted with ease even with the...