Found in a 1964 Electrronic Design, this circuit is intended to control analog video signals. The circuit has an attenuation of 45 dB at 20 kHz.
Found in old documentation about neon lamps, this circuit shows how to add a simple blown fuse...
This circuit was found in a 1980s documentation. It triggers a relay when liquid from a reservoir...
For counting to values higher than 16, many 4520 can be cascaded as shown in Figure . The EN...