This filter configuration used in telecommunications uses 4 Jaumnann crystals that are interesting for low and medium frequencies. The circuit is from an 80's documentation.
This circuit was found in the March 1982 Radio Electronics magazine. The component is a special...
This 1969 Electronics World power supply has 5 V to power digital circuits and a 170 V output for...
Found in Radio Electronics from the 90s, this circuit uses a thermistor as a sensor that can have...