On Monday, October 29, 2018 at 5:34:29 AM UTC-7, jurb...@gmail.com wrote:   
   > The vibrator in an old car radio. Not only does it oscillate without   
   > transistors or tubes, some rectify without diodes. A second set of contacts   
   > make for a synchronous rectifier.   
   If you ever opened one, you would find it is basically an electromagnet   
   configured as a buzzer, just like the one you probably built in grade school   
   science or shop class, and just like the one you mentioned a couple weeks ago.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)