Latching relay

Hello this is my first post so firstly greetings from me in UK.

I have a Durite 0-728-02 latching relay to activate the ignition supply from a momentary switch built into my race car steering wheel. The wheel buttons have a 300ma max on wires song have a 300ma in line fuse. The pins are all wired up correctly I think by a thread I saw on here.

30- neg
S- 12v signal for switch
56- per live
56b- to ignition supply
56a- not used

The problem I have is that the relay latches but does not latch off when pressed the momentarty switch again. It worked at first one but now not? I have 2 other relays the same operating a rain light and fuel pumps from the momentary switches on the dash and they do the same.
Please can anyone shed some light?

Thanks in advance
Dan

Oh no, not the bluddy 0 728 02 again!
I looks as if your wiring is ok assuming you mean the same as at durite 0 728 02 relay wiring (page 5, top reply).

As per that thread I still can't find any info on the coil current. Assuming you have clean switch S- GND connections, maybe overall resistance is limiting the required toggle-off current?

Incidentally I'd be more inclined to use a 300mA current limiting circuit if switch current/protection is that critical since a 300mA fuse will allow 330mA for maybe hours and 1A for 30-50 seconds. Of course that depends on switch characteristics, and a current limiter will introduce a voltage drop (eg, 1.2V if using an LM317), but usually such low current interfaces are left unfused.
If switches are that critical or expensive it's better using some buffer - eg, transistor or intermediate relay.

You will find that's a high low headlight switching relay.
It would be cheaper to use a dual coil latching relay from RS Components or Maplin, then feed a regular relay from there, total cost about £7, also you'll need a kill switch for the ignition (goes to the second coil to "unlatch" the relay and turn the engine off.
Go to the RS Components website and enter 12V. dual coil latching relays, any current from 200 milliamps will be sufficient. About £4, then a standard relay, RS, Maplin, Halfords £3-5.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Shoot we're doing it again Peter.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Ok I did not mention space is very limited hence why I have just one relay. It's all mounted behind the dash and its a single seater. Weirdly though it all worked fine for about a minute but then all relays went unresponsive?

A normal or new type "half cube" relay plus the latch would take up less space than the original.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Ok I will see if I can figure out why it's not un latching

Would the 300ma fuse be the issue by adding too much resistance?

No.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Well, unlikely...

But yeah Howie, here we go again... safety & reliability, THAT relay, blah blah.

I know I would not want a steering wheel switch to turn on ignition and pumps etc. Maybe to kill the ignition, and maybe the fuel pump even tho my fuel pumps are automated (unlike idiots that control them from IGN direct, or oil pressure switches...).

But I have been finding more people that use relays for ignitions - either the >$600 types else cheap but usually non-redundant relays. Not that Ive searched but I haven't read yet that any have resulted in accidents or write offs or deaths tho I expect like oil-pressure switched fuel pumps they won't seek to publicise their embarrassment or liability.
Of course IMO it's hilarious when such relays are installed for engine kill AND battery isolate systems. Not that such outcomes should be considered funny, but I'm sick of ongoing arguments and ignorance.

With apols for my rant, but in case it causes some to rethink IMO hazardous implementations...

Ok I just got a relay out. I have wired it up as the first post. There is not live from 56b only perm live all the time on 56a? It was latching on and off when on a bench

I was once confused by that relays info. Some said it was 56a live permanently with 56b as a (latching) on-off whereas other said it was a typical (headlight) latcher - ie, 56a else 56b.
Of course I can't see the point of the former.

IMO if it's permanent 56a then the coil is not activating else the relay has failed.

Switching is achieved by using a single electrical pulse across the coil terminals 30 (12V +) and S (to switch or ground -) to energise the internal coil and is triggered by the use of a momentary on-off switch, which reduces the time duration the switch is kept closed, the pulse pulls the coil in to switch the circuit from 56 (+feed) and 56a (+feed) to 56 (+feed) and 56b (+feed or not connected for off), once the momentary on switch is pressed again the coil is energised again and the circuit switches back to 56 and 56a.

Nicely pasted from thetoolboxshop.com.
I wonder if anyone can translate or simplify what that means? (Especially wrt to BOTH diagrams - ie, their schematic versus the relay housing's schematic.)

It ain't a turn on/turn off device it's a latched changeover device, identical to Mr. Ween's famous Hella headlight relay, in normal use, an electrical dip switch.
Not exactly what I believe our OP intends to use it for, still running with an Omron latcher and a mini cube, much simpler and fail safe.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

I interpret it as a dip switch aka changeover or normal SPDT but mechanically latching despite the contradictory to most relay pic & circuit diagram shown on thetoolboxshop which is like the DNI 0127 (111-941-583) shown on thesamba.com (maybe causing the "permanent" thruput confusion?) - VIZ:


Yet another example of a site I wouldn't use, not that I find Durite's info much good either - eg, why not include in their 0-740-95 datasheet that's it's a 7 minute delay instead of emphasising or confustigating with their "individually programmed ‘PIC’ controlled timer"; or do they tailor each relay or enable user programming? IMO a lack of specification & clarity - as if not including coil resistance or current isn't bad enough.
I seem to be copping a lot of those dubious sites lately... Maybe I need to reOxygenate myself?

https://r./sehMjF

So this?

https://r./sehMjF

Link not working. Can someone tell me where in uk I can get the bistable latching relay which the instruction to my wheel says? Is that the omron you are suggesting? What a mini cube?

I told you where to look.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

RT424A12 Will this one doe howie?

No, single coil, you need a twin coil, on and off.





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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Here you go.
Omron G6AK-234P 12DC

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

howie ll wrote:

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No, single coil, you need a twin coil, on and off.

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Thanks howie would you be able to tell me a product number for what I want? I don't mind paying for your advice

We crossed paths.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Thanks howie. Intake it I need to connect a normal relay to this as its low ampage? Also the mini cube thing is that like a case? Cheers much appreciated

And also I take it you need a reset switch, so 2 switches needed?

Yes to all of the above, push ignition, push start, push off.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Ok so the latching relay has 2 momentary switches connected to it, one to activate the ignition and one to turn ignition off?

To mount it I need a cube? Can't find these anywhere online?

The latch relay is connected to a normal relay?

Sorry these area last notes to confirm and I will not keep bothering you lol

Again yes, mini cube, RS has them, otherwise regular 4 pole from Halford, Maplin etc.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Ah, amazing what a bit of oxygen can do for cavitation. Now for the tractating coffee...

So we're now at page 4. Hmmm...

Dan, if you go down the 2-switch route, have you considered the classic SPST relay circuit (see eg capacitor value for latching relay? - especially the 8th reply - which has appeared many times since (eg, latching relay?) ...and beats this gem of an idea eh?).
It uses any typical SPST relay and no circuitry excluding the diodes in case lower than load current switches are used, hence easy & cheap to source, build, & repair.

For a single button toggle I like the old inverter circuit as per single button latching relay but its switch is circuit internal, ie NOT to GND or +12V. HotWaterWizard has some great circuits as per that last link and elsewhere tho some use multiple relays which I am not a fan of (I prefer circuit logic to relay logic).

For a GND or +12V toggle relay there is also the 4017 based circuit. Tho IMO the "divide by 10" decade counter 4017 seems excessive as a mere divide by 2 counter it's nice because it can have a power-on reset feature and it's easily expanded to more than 2. Transistor or IC flip-flops would seem a more logical choice but I can see why some headlight relays etc use the 4017 instead - especially these days if web product information is so danged ambiguous, misleading or lacking!!


Tho I'm not a fan of mechanically latching relays except where zero power draw is required (except when changing state) I recall liking the OMRON latchers that Howard referred to (low coil currents; small size; good specs, etc).
If they are underrated they can drive normal relays. IMO that's preferable anyhow to keep heavy power short (ie, battery-relay-IGN) whilst keeping control nearby with short signal wires (and optional bypass/override switches) etc.