I know that a relay can remain in closed circuit under current and open without current (or the other way around, depending on the relay), but is there any sort of relay that just requires any power to be applied to be switched, then remains under that state (closed or open) without any power applied? Even better if one can suggest one that is manufactured in solid state (opposed to relays that have moving parts).

Wall switches do not fit this description since those need to be switched mechanically and I'm looking for one that switches electrically.

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    \$\begingroup\$ Latching Relay. \$\endgroup\$
    – brhans
    Mar 23, 2016 at 1:46
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    \$\begingroup\$ What @ brhans and @ BobT said. Mechanical Latching Relays are common. They also come in solid state forms, just less common. Just google solid state latching relay. \$\endgroup\$
    – Passerby
    Mar 23, 2016 at 1:53

1 Answer 1


Sure... Those are pretty standard. They're called latching relays. They are bi-stable which means they only need power to switch, and will stay in their switched state without power needing to be applied. See this article for details: http://www.serelays.com/library/section7/105A_755.pdf.

  • \$\begingroup\$ Thank you for the answer. Do you know any equivalent without moving parts? \$\endgroup\$ Mar 23, 2016 at 1:49
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    \$\begingroup\$ @gabrieldiego: In solid-state, thyristors, which include SCRs and TRIACs, are a family of devices that stay on once triggered (but they turn off when the thru current drops to zero). \$\endgroup\$
    – uint128_t
    Mar 23, 2016 at 2:25

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