This sound relay or Vox was found in 70s RCA documentation. SCRs can be common types today and transistor a BC558. The circuit is for the 110V power grid.
This system of sequential lights for shop windows, discotheques, stores, does not use integrated...
This circuit was found in an Elektor from the 90s. Next to the circuit we have a table with the...
This sensor was published in Radio Electronics magazine in April 1962. The two-transistor circuit...