Latching Switches

Vehicle prep and projects

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NeilandPat
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Latching Switches

Postby NeilandPat » Mon Feb 20, 2017 1:25 pm

I am looking for a push button style latching switch that when pushed activates a circuit. However, when the power is disconected it releases and has to be re pushed to re activate.
I think it would have to have electronic latching as oppose to a mechanical latch. It may even involve a relay.

Any thoughts on how to do this and where to get one would be well received.

Its 24v by the way

Neil

jonbull
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Re: Latching Switches

Postby jonbull » Mon Feb 20, 2017 1:58 pm

How about a normally open relay with a push to close switch with a live feed from the "actuated circuit" also feeding the switched side of the relay. Push down,..powers relay then power is maintained by the actuated side when the push button is released. Power fails, relay drops out..............

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NeilandPat
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Re: Latching Switches

Postby NeilandPat » Mon Feb 20, 2017 2:06 pm

Thanks Jon

Not an electronics wiz but trying to get my head around that

Are you saying use a momentary switch to activate the relay which will connect an ignition "On " Circuit. Then use the power from that ignition "On" circuit to keep the relay activated .

ie when the power is cut it all unlatches


Sound possible though

Cant help thinking that there must be an off the shelf switch out there that is may suitable

Neil

crinklystarfish
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Re: Latching Switches

Postby crinklystarfish » Mon Feb 20, 2017 6:40 pm

Not sure what you're trying to achieve Neil.

When you say 'when power is disconnected it releases' do you mean something like turning off the ignition causes the circuit to open?

So, push switch, circuit closes and whatever you are powering up receives power, turn ignition off and circuit opens - turning whatever it is you're powering off.

But simply turning ignition on again does not restore circuit power - ie you then have to manually activate the switch again. Is that what you're wanting to happen?

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NeilandPat
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Re: Latching Switches

Postby NeilandPat » Mon Feb 20, 2017 11:07 pm

Steve

That is exactly it.

Unless I see a switch which will do this I think Jons idea is the solution.

Neil

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Zoltan
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Re: Latching Switches

Postby Zoltan » Mon Feb 20, 2017 11:48 pm

I think you need a contactor type switch such as you'd use on machinery so that an electromagnet holds the load switch in when it is powered up but when the ignition current is switched off the electro magnet releases and a spring pushes the load contacts open
What about a remote starter solenoid, what sort of load are you putting through the switch?

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christyler
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Re: Latching Switches

Postby christyler » Tue Feb 21, 2017 12:30 am

this is the easy way to do it.
excuse the shitty drawing

Image

crinklystarfish
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Re: Latching Switches

Postby crinklystarfish » Tue Feb 21, 2017 8:19 am

Had similar requirements in misspent days messing with N2O. I did it a different way but the attached image is swiped off internet (thanks hotwaterwizard ) showing Jon's way using a simple make/break 24V relay.

To de-americanise it:

Push Start = simple momentary switch
Hot = + tap from an ignition auxilliary circuit
Load = + feed to whatever it is you're powering
Com = neutral

NB You'll need to make sure:

the aux ignition circuit you tap
the mom switch
the relay

are ALL capable of carrying the max load to power whatever it is you're powering.

If whatever you're powering needs a heavy current you'll probably need to introduce a further relay powered by the 'load' circuit - or do it a different way altogether.
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NeilandPat
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Re: Latching Switches

Postby NeilandPat » Sat Mar 11, 2017 5:42 pm

Fitted this relay setup today. Small loop from load back to ignition live feed from switch and it worked a treat

Momentary switch activates it all and it stays on until the power is cut then it needs re activating

Perfect

Thanks for the help

The only problem I had was I needed to break into the fuel line from the tank to the pump . I thought it was 10mm but its not, Its 11m .

Who on earth uses 11m for anything , well Mercedes did. No fitting available there then

Neil

Neil

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Brian-reynolds
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Re: Latching Switches

Postby Brian-reynolds » Sat Mar 11, 2017 8:21 pm

NeilandPat wrote:
The only problem I had was I needed to break into the fuel line from the tank to the pump . I thought it was 10mm but its not, Its 11m .

Who on earth uses 11m for anything , well Mercedes did. No fitting available there then

Neil

Neil


11m pipe! Wow, that is one hell of a pipe! Your engine must drink a lot of fuel.....

If you had a decent knife you could have whittled it down a bit.....

B.


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