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.
Found in American documentation from the 1970s, this circuit is intended for amplifying analog TV...
This circuit uses only passive components and the instrument can be a microammeter or the lowest...
This oscillator generates quadrature signals, that is, with a 90-degree lag. The frequency is...