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   REPLYADDR andrews@sdf.org   
   REPLYTO 3:770/3.0 UUCP   
   MSGID:  9b94e192   
   REPLY:  7c626403   
   PID: SoupGate-Win32 v1.05   
   On 2025-02-10, Mike Scott  wrote:   
   >   
   > Thanks for the reply. I was considering complete units (like eg url   
   > below (*)), which differ in operation. They take a pulse on a single   
   > logic-level input, and flip-flop between states: my query is how to   
   > reset from a random state to the power-up state.   
   >   
   > The one you reference uses either reverse polarity or a 2nd coil to flip   
   > and flop.   
      
   [ https://www.amazon.co.uk/dp/B08LCTTR4Z/ ]   
      
   Those are not conventional latching relays but standard one with   
   an external latching circuit.  The semantics oare defiferent.   
   latching relays use two coildand don't need power to maintain their   
   state.  The page tells you all you need to know, namely the relay   
   is not energised when power is first applied, so conductivity is   
   between NCx and COMx, switching to NOx and COMx on the first pulse.   
      
   Lack of proper data sheets is one of the reasons I'm not generally   
   a fan of commercial building block modules like this.   
      
   --   
   Andrew Smallshaw   
   andrews@sdf.org   
      
   --- SoupGate-Win32 v1.05   
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