XPost: sci.electronics.design   
   From: nospam@gte.net   
      
   "ehsjr"  wrote in message   
   news:gA56j.13916$Lg.11052@trndny09...   
   > West wrote:   
   > > Using a 555 or similar type chip, I would like to have the output change   
   > > from low to high or high to low every time the system is turned on. IOW,   
   the   
   > > output is a high, then the system is turned off. When the system is   
   turned   
   > > back on, the output goes low. Each power up of the circuit changes or   
   > > "flips" the output state. I am willing to incorporate CMOS and a battery   
   > > back up in the design. Some of the ideas I entertained is a divide by 2   
   in   
   > > front of the toggle, giving me the same state every other time. However,   
   I'm   
   > > not sure how to do this practically or if it's the way to go. Any   
   > > suggestions out there? All comments welcomed and thanks.   
   > >   
   > > west   
   > >   
   > >   
   >   
   > Can you use a mechanical device? A motor driven   
   > cam or something like a car door lock solenoid,   
   > with switches & logic to determine direction?   
   >   
   > A mechanical setup has the disadvantage of slow   
   > speed/large size, and the advantage of retaining   
   > the last "setting" forever without needing power.   
      
   I am now studying latching relays. If I go that way I need to find a small   
   one. The criteria again is : power on gives a logic low; next power on gives   
   a logic high. IOW shutting the power off does not change states.   
      
   west   
   >   
   > Ed   
      
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