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   REPLYADDR mjmahon@aol.com   
   REPLYTO 3:770/3.0 UUCP   
   MSGID:  a98397b9   
   REPLY:  7c626403   
   PID: SoupGate-Win32 v1.05   
   Mike Scott  wrote:   
   > On 10/02/2025 12:33, Joe wrote:   
   >> On Mon, 10 Feb 2025 09:12:32 +0000, Mike Scott   
   >>  wrote:   
   >>   
   >>> Hi all. I think a latching relay is the way to go for a pico-based job I   
   >>> have in mind. However the prevalent ones all seem to be controlled by a   
   >>> pulse on a single input wire which flips and flops the state.   
   >>>   
   >>> No doubt they reset to a known-state at power-up. But I see no   
   >>> indication of any way of resetting them to that known state without   
   >>> turning off the power - eg after reloading the pico control program.   
   >>>   
   >>> Has anyone used these and can offer advice please? Thanks.   
   >> I am using the HFD2/005-S-L2-D dual coil relays.  They work for my   
   purpose....   
   >>   
   >> See: https://source.hongfa.com//Api/DownloadPdf/323   
   >   
   > 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.   
   >   
   >   
   >   
   > (*)   
   >    
   >   
   > (No, I'd not pay that sort of price :-) )   
   >   
      
   In that case, the only reliable way to proceed is to provide a way to sense   
   the current state of the relay so that the desired state can be selected.   
      
   --   
   -michael - NadaNet 3.1 and AppleCrate II:  http://michaeljmahon.com   
      
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