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help with a 12v control circuit

MADEHN

Aug 27, 2023
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I am a great mechanic, a good carpenter, 1/2 way electrician, but a total doof when it comes to control circuits. I have a need that when a 12 volt circuit is energized, it fires a MOMENTARY 12volt signal to a latching relay. I currently have it activating a relay that signals the latching relay unfortunately the latching relay cannot handle a continuous signal current. Basically i need to flash a quick jolt to the latching relay then go back to no signal-- how can I accomplish this?
 

Bluejets

Oct 5, 2014
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several ways...possibly 555 simple enough.
One can get the mono stable modules online Ebay etc for a couple of dollars.
You could use a transistor setup but the above are already made so......

https://www.ebay.com.au/itm/185460563580

What does the rest of your circuit look like as it might be done simply with a cap and a small signal transistor.
 
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kellys_eye

Jun 25, 2010
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I have a need that when a 12 volt circuit is energized, it fires a MOMENTARY 12volt signal to a latching relay.
You need a MONOSTABLE although it is perfectly possible to achieve what you want using an ordinary relay by using an extra set of contacts to short across the activating signal. You will, of course, need a button to de-energise the relay (or rely on the removal of the power source to achieve the same result. I don't know what your specific application is).
 

AnalogKid

Jun 10, 2015
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This could be a simple as adding one capacitor, but not without more information.

For your relay - manufacturer / part number / coil current / coil wattage / datasheet / link to product page

- anything - ?

ak
 

MADEHN

Aug 27, 2023
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I think the monostable will do the job for me-- thanks for the quick assistance and many thanks to all who replied.

a little more information- this is for a security system on a boat- basically when you step on a pressure switch mat, it energizes a latching relay-- this latching relay then sends power to 6 other relays which turn on horns, strobes, sirens, beacons etc some of which are quite heavy amperage- thus powering them thru relays rather than running power thru the latching relay.
 

Bluejets

Oct 5, 2014
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basically when you step on a pressure switch mat, it energizes a latching relay
As far as I can see you already have your voltage pulse....the mat switch will turn off again after one steps off the mat....all-be-it a second or so pulse.
 

AnalogKid

Jun 10, 2015
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Relay coil current or resistance?

Also, what if someone steps on the mat after everything is up and running? Wouldn't the latching relay go to the off state?

ak
 

Bluejets

Oct 5, 2014
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Quite possible to set up a basic latch circuit (not a mechanical latching relay as such) with your existing pressure mat triggering the alarms.
Then it would be a simple matter of an internal "secret location" alarm reset button.
With this arrangement one could jump up and down on the pressure mat until the cows come home and the alarms would merrily carry on beeping until the "boss" hits the reset button.

OR...someone turns off the power....... :rolleyes:

As below......
 

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atemple492

Oct 20, 2023
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To achieve the momentary signal to the latching relay, you might want to consider incorporating a timer or a pulse generator into your circuit. This will allow you to send a short, controlled pulse of voltage to the latching relay when the 12-volt circuit is energiSed. This way, it won't receive a continuous signal current that it can't handle.
 

Bluejets

Oct 5, 2014
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To achieve the momentary signal to the latching relay, you might want to consider incorporating a timer or a pulse generator into your circuit. This will allow you to send a short, controlled pulse of voltage to the latching relay when the 12-volt circuit is energiSed. This way, it won't receive a continuous signal current that it can't handle.
Perhaps like in the previous suggestions above, you think..............? :rolleyes:
 
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