From: bretcahill@aol.com   
      
   This must be a really really common problem and the only reason it is   
   difficult to find on youtube is the wrong search terms:   
      
      
   If a device has a power on button latch switch and you want it to turn on and   
   off like a light bulb, i. e., when the power supply is plugged in or a relay   
   connects the power, or for solar, when the sun comes up, is it a common   
   solution to run a wire from    
   the power supply through a cap and maybe a large drain resister in parallel   
   then to one side of the latch switch?   
      
   The current would flow through the cap just long enough to set the latch   
   switch before the cap is charged and stops the flow.   
      
   Then the device turns on and stays on until power is disconnected.  The   
   process can repeat after the charge drains off the cap.   
      
   First check the voltage through the on switch is the same as the power   
   supply.  (This will not werk on a lap top.)   
      
   I'd need some idea of the time it takes to latch and some thresh hold voltage   
   for the latch to select the cap and resister.  Maybe look at it on an   
   oscilloscope.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)