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 can operate with 5 uV to 1 mV input signals from low impedance sources such as...
This very simple circuit with neon lamps indicates who pressed the button first, lighting the...
This circuit was originally designed for the practice of Morse code, something common in 1966, the year...