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 obtained from an American documentation from the 1980s. The T1 triggering...
Found with variations on this site, this circuit was taken from an American documentation from the...
With the original components, suggested in a Motorola documentation from 1971, this circuit can...