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From: Mike Scott <usenet.16@scottsonline.org.uk.invalid>
Newsgroups: comp.sys.raspberry-pi
Subject: Re: latching relays
Date: Mon, 10 Feb 2025 14:02:55 +0000
Organization: Scott family
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On 10/02/2025 12:33, Joe wrote:
> On Mon, 10 Feb 2025 09:12:32 +0000, 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. 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.



(*)
<https://www.amazon.co.uk/%E3%80%90%F0%9D%90%84%F0%9D%90%9A%F0%9D%90%AC%F0%9D%90%AD%F0%9D%90%9E%F0%9D%90%AB-%F0%9D%90%8F%F0%9D%90%AB%F0%9D%90%A8%F0%9D%90%A6%F0%9D%90%A8%F0%9D%90%AD%F0%9D%90%A2%F0%9D%90%A8%F0%9D%90%A7%E3%80%91-Flip-Flop-Self-Locking-Bistable/dp/B08LCTTR4Z/ref=sr_1_6?crid=1X3LJ40EW31PS&dib=eyJ2IjoiMSJ9.RT0p7Xw5aJ0Swdoibedry1USbeWgVfw825dY065GrU69oETh7LUKVWnWUjyVpSszgw3nD-k3IJb0JqTj4_dub2sNKoCG5RiD66Y0AXX_2FUXHDzt-3kELJdgbFjrV-fEzfWkFsXFRRZC4yqrRIh2DzCvMEDlqaV1C66gP9H9OtABUWO3miMmsfqPY2OvxIz4ORJ-gEzJ81GrtiW30IbGrE9nNDx5D6MQ_hjlXLgsBaq1iAptiO6lvwn31IMh4vJXsSVS3a7ckkG1MO4Z6DWTI1Og3Tw5QgXRDR7L9c07Uk7Mtd0mccGx33TGtHFf0Q7I_ojHzk-TeNSON2usCmhqoBpo3qK7DbckUoRsRbuv2TLMwKsO_4fpMxQxZk8ba4n19QVDlRdXVJedgWzL5ye6aH0bLnlc5tk1Bk9IsieO-wIIDOqHja6LmsdPjwi52Ltq.uR8nBzN6Nf-BBzOjkOcmfdgfxpIuRN1Ed4Spc0VtRUA&dib_tag=se&keywords=5v+dpdt+latching+relay&qid=1739195865&sprefix=%2Caps%2C72&sr=8-6>

(No, I'd not pay that sort of price :-) )

-- 
Mike Scott
Harlow, England