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Relays

Big Nige

New Member
I have a a momentary switch which activates a 12V* DC voltage; I want to use this voltage to trigger a relay to activate a 15V DC current to operate a remote doorlatch; is this non-latching relay suitable: Finder 3451.7012.0010 SPDT PCB Mount Non-Latching Relay, 12V dc Coil 6A? (ultra slim due to space constraints) * the supplied voltage is actually 15V DC but due, I suspect, to length- and possibly type of cabling, there is a voltage drop to 12 +/- .25V at output.
 

gophert

Well-Known Member
Most Helpful Member
I have a a momentary switch which activates a 12V* DC voltage; I want to use this voltage to trigger a relay to activate a 15V DC current to operate a remote doorlatch; is this non-latching relay suitable: Finder 3451.7012.0010 SPDT PCB Mount Non-Latching Relay, 12V dc Coil 6A? (ultra slim due to space constraints) * the supplied voltage is actually 15V DC but due, I suspect, to length- and possibly type of cabling, there is a voltage drop to 12 +/- .25V at output.
That slim relay requires 12v applied to the coil and the coil has 840 ohm resistance (15 mA current will flow).

Once the coil is activated, the relay's switch can handle loads of 230vac at 6 amps
 

Reloadron

Well-Known Member
Most Helpful Member
What are the specifications on the door latch? The door latches I have worked with needed very low current so there is a possibility you really don't need a relay.

Ron
 

Big Nige

New Member
1. Thanks gophert; a) should the coil activate immediately, ie as soon as the momentary button switch is pressed, or might it take .5sec perhaps? b) would the +/- .25V tolerance in the 12V I mentioned above make any difference? 2. Not sure what current the latch draws RR, I'll try and test it/find the spec and get back to you.
 

Reloadron

Well-Known Member
Most Helpful Member
All of this would go much, much better if the make and model number of the locking mechanism were known. Electric door locks also called electric door strikers can operate in several modes, things like fail safe depending on what is happening if power is lost. Some use a basic solenoid and some use a small motor to drive a tumbler. The response times vary with the design but a very basic striker (solenoid) type will normally respond in less than 0.5 second and the door can only be opened while the circuit is complete as in a button held down. Most of this information is found in the data sheet for a specific model.

The process all begins with you making a draft or list of the features you want or need and with that list finding a make and model which fit your needs within your budget or price range. Only with a data sheet will you know how much current the unit will draw and select a switch and power supply accordingly.

Ron
 

gophert

Well-Known Member
Most Helpful Member
1. Thanks gophert; a) should the coil activate immediately, ie as soon as the momentary button switch is pressed, or might it take .5sec perhaps? b) would the +/- .25V tolerance in the 12V I mentioned above make any difference? 2. Not sure what current the latch draws RR, I'll try and test it/find the spec and get back to you.
Most relays move quickly and you can expect much less than 0.5 seconds. Give it 0.05 to 0.1 if you have power supply that meets the specs of the coil (almost any 12vdc adapter will be fine for the 840 ohm coil.

Most relays that are high enough quality to have a published datasheet will state the latching voltage, the holding current and the fallout voltage (not exactly those terms but those concepts. Most can handle a few Volts above the stated voltage.
 

Big Nige

New Member
Thanks Chris for the spec sheet, and Ron for the sound advice - I agree; however it's an old/existing door lock and no details or make visible, it's the solenoid type which lifts a latch, allowing the rotating striker to move as the door is opened. I've got the relay but it's closed circuit until activated and it needs to be open; I've contacted Finder to query but attach the pic here in case there's something obvious I've missed.
 

Attachments

ChrisP58

Well-Known Member
If the relay truly has SPDT contacts as shown in your drawing, then it has an open contact and a closed contact.
The normally closed contact is between pins 11 and 12. The normally open contact is between pins 11 and 14.
 

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