Re: latching relays

On Mon, 10 Feb 2025 18:47:21 GMT, David Higton <dave@davehigton.me.uk> wrote:

In message <vocfu0$14uka$1@dont-email.me>
         Mike Scott <usenet.16@scottsonline.org.uk.invalid> 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.

>
It has always been my understanding that they retain their current state
indefinitely, until the next pulse.  So there is no such thing as a
reset state.
>
David

Yes they remain their state BUT sometimes Arduino likes (from experience) & probably Raspi's give of spurious pulses on startup
which can be/needs to be prevented:

Known issue and solutions are on the internet i.e.
https://forum.arduino.cc/t/relay-turn-on-whenever-i-turn-on-arduino/644387

If the state needs to be knows between bootups, store the last setting in a file before/after switching and if needed send the
proper setting again after bootup.  That is why I like dual coil relays ;-)