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'[EE] latching relay question'
2011\10\25@145446 by alan smith

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www.aislu.com/documents/HG30T_EN_S101027V1.pdf

If you look at the drive principle, its saying a position DC to latch, and a negative DC to unlatch?  Is this the same thing as just reversing the DC voltage on the coil? Ive not used latching relays before....

2011\10\25@151739 by Carl Denk

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This is not what I am accustomed to seeing for a latching relay, where each pulse (only one polarity is used) switches the relay. But, it is clear for this relay, one polarity closes the contacts, and the other (negative) polarity opens the contacts. As I see it, this is a neat way to control the relay from an AC source, with 2 wires, and assure that the action ( on or off ) is correct. With the latching relay controlled by a pulse, you don't know if it's on or off. This is accamplished with a minimum of components. But this isn't a problem with local control of something where you can see a light on or off, or a motor is running. A closet pull chain controlled light is a good example.

On 10/25/2011 2:54 PM, alan smith wrote:
> http://www.aislu.com/documents/HG30T_EN_S101027V1.pdf
>
> If you look at the drive principle, its saying a position DC to latch, and a negative DC to unlatch?  Is this the same thing as just reversing the DC voltage on the coil? Ive not used latching relays before....
>
>
>

2011\10\25@152802 by Dwayne Reid

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At 12:54 PM 10/25/2011, alan smith wrote:
>http://www.aislu.com/documents/HG30T_EN_S101027V1.pdf
>
>If you look at the drive principle, its saying a position DC to
>latch, and a negative DC to unlatch?  Is this the same thing as just
>reversing the DC voltage on the coil? Ive not used latching relays before.....

Yep.

dwayne

-- Dwayne Reid   <spam_OUTdwaynerTakeThisOuTspamplanet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax
http://www.trinity-electronics.com
Custom Electronics Design and Manufacturing

2011\10\25@152849 by Bob Ammerman

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From: "alan smith" <.....micro_eng2KILLspamspam@spam@yahoo.com>

>http://www.aislu.com/documents/HG30T_EN_S101027V1.pdf

>If you look at the drive principle, its saying a position DC to latch, and
>a negative DC to unlatch? Is this the same thing as just reversing the DC
>voltage on the coil? Ive not used latching relays before....

Yep!

-- Bob Ammerman
RAm Systems

2011\10\25@153326 by Isaac Marino Bavaresco

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Em 25/10/2011 16:54, alan smith escreveu:
> http://www.aislu.com/documents/HG30T_EN_S101027V1.pdf
>
> If you look at the drive principle, its saying a position DC to latch, and a negative DC to unlatch?  Is this the same thing as just reversing the DC voltage on the coil? Ive not used latching relays before....


There are two types of latching relays, the one with one coil that
closes when power is applied to the coil in one polarity and opens when
the opposite polarity is applied.
The other type has two coils, applying a pulse to one coil closes and a
pulse to the other coil closes it. Some two-coil relays also work with a
single coil if the polarity of the signal is reversed.

There is a third type of latching relays, the bi-stable type. In this
type, applying one pulse to the coil makes it close, applying another
pulse makes it open and so on.


Best regards,

Isaac

2011\10\25@154354 by Isaac Marino Bavaresco

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Em 25/10/2011 17:33, Isaac Marino Bavaresco escreveu:
> Em 25/10/2011 16:54, alan smith escreveu:
>> www.aislu.com/documents/HG30T_EN_S101027V1.pdf
>>
>> If you look at the drive principle, its saying a position DC to latch, and a negative DC to unlatch?  Is this the same thing as just reversing the DC voltage on the coil? Ive not used latching relays before....
>
> There are two types of latching relays, the one with one coil that
> closes when power is applied to the coil in one polarity and opens when
> the opposite polarity is applied.
> The other type has two coils, applying a pulse to one coil closes and a
> pulse to the other coil closes it.


Sorry, "a pulse to the other coil OPENS it"...


{Quote hidden}

>

2011\10\25@155921 by Bob Blick

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On Tuesday, October 25, 2011 11:54 AM, "alan smith" wrote:
> www.aislu.com/documents/HG30T_EN_S101027V1.pdf
>
> If you look at the drive principle, its saying a position DC to latch,
> and a negative DC to unlatch?  Is this the same thing as just reversing
> the DC voltage on the coil? Ive not used latching relays before....

Yes.

Relays in home thermostats use latching relays with that method of
operation, also they can have a center-tapped coil so you drive one side
or the other, same idea of reversing magnetic field. A permanent magnet
inside the relay keeps the relay latched.

Cheers,

Bob

--
http://www.fastmail.fm - Same, same, but different...

2011\10\25@194313 by Robin D. Bussell

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A related non obvious thing that happened to me the other day: a relay driving circuit that worked fine the first time round stopped working when I built a second. The relay was a standard 5v non latching miniature type bought from maplin as " BT type 47 relay".
Eventually I noticed that the second relay I bought was a different part ( even though sold as the same maplin part number ) and this one had a coil that only operated in one polarity! I guess there is a permanent magnet I'm there to reduce the operating current or something. I was completely surprised by this having spent far too long probing around convinced that the second copy of the driving circuit must be at fault. Maybe one day this tale will save one of you the same head scratching :)
Cheers,         Robin.

On 25 Oct 2011, at 21:01, "Bob Blick" <bobblickspamKILLspamftml.net> wrote:

{Quote hidden}

> -

2011\10\26@072444 by Sean Breheny

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Sometimes relays will also have an integrated diode (in parallel with
the coil) on the coil to suppress inductive spikes - in which case the
coil will only operate in one polarity. Sometimes they use two diodes
(one in series, the other in parallel) to protect the parallel diode
from damage if the coil is hooked-up backwards (in which case a very
high current would flow through the parallel diode).

Sean


On Tue, Oct 25, 2011 at 7:43 PM, Robin D. Bussell
<.....RobinBKILLspamspam.....excelerate.info> wrote:
{Quote hidden}

>> -

2011\10\26@100504 by alan smith

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Thanks for all the replies.

So I am thinking using a Hbridge to drive this...using the forward and reverse controls to swap the polarity might be a good solution?  Using the Hbridge prevents any chance of having + and - connected at the same time.

So I need a "on" and "off" pulse tied to the Hbridge input control.  Now of course I could use a PIC to do this, thats easy....or I could use a bunch of one shots with F/F (the turn on...turn off....pulse...will come from another processor)

Any clever ideas on this?


{Original Message removed}

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