Found in EEE documentation, this circuit can have the duration and frequency adjusted separately. SCRs can be modern equivalent types.
This circuit was published in a 1977 Radio Shack catalog. The PNP transistor may be BD135 and NPN...
May 2017 - ROHM is announcing the availability through Mouser Electronics of a broad line of fast...
This temperature compensated circuit was found in a Popular Electronics of the 1990s. The circuit...