This circuit was found in a Philips documentation from 1966. Its purpose is to drive the solenoid of an electric typewriter of the time.
This sound relay or Vox was found in 70s RCA documentation. SCRs can be common types today and...
This two-door doorbell was found in a 1990s US publication. The circuit is still current as...
This sophisticated circuit using a liquid crystal display was found in Radio Electronics from the...