Interesting - but nothing like those on my board. I no longer have it so can't take pics. The description isn't that clear - does it take (near) zero current when made or just a reduced amount? For long battery life it would need to be zero. Nor did the noise it made when the 'switch' operated sound anything like a relay.
No current at all. Imagine a balanced metal arm pivoted in centre and a coil at each end with some remanent magnetism. A current pulse through either coil is sufficient to overcome the small static magnetic pull and trip the bistable to the other condition. The Danfoss WP75H uses a much larger Gruner 703H to switch up to 25A for an immersion heater.
This article has a short explanation and some driving circuits:-
Excellent - thanks for that. I can think of a few uses I could put them to.
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