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Topic: Need Help(providing correct Voltage) (Read 619 times) previous topic - next topic

kylec123

Nov 09, 2011, 04:39 am Last Edit: Nov 09, 2011, 05:36 am by kylec123 Reason: 1
I'm very new with working with electronics like this and need some advice.  

I'm trying to build and RFID door lock(yeah i know..very original) that triggers a 12V electric strike lock.  How  do i provide this power?  As much description as possible would rule.  I'm a noob with the hardware/physical side of this.

CrossRoads

http://www.dipmicro.com/store/DCA-1210

How much current do you need?

You can use arduino to read the RFID, turn on a relay and let the 12V be applied across the strike lock, which I imagine is similar to a solenoid.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

kylec123

"and let the 12V be applied across the strike lock,"

I think this is what i do not know how to do. 

CrossRoads

You're going to have some electromechanical thing that moves out of the way to unlock the door, yes?
Pick a mechanism for that, mount it, and bring out two wires from to connect up to a relay so that current can be run thru it similar to a motor.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

kylec123

Ok, so i need a relay.

This is what im using
http://www.ebay.com/itm/Electric-Strike-Door-Lock-Fail-Secure-NO-Long-plate-/160446497488?pt=LH_DefaultDomain_0&hash=item255b5b42d0#ht_2629wt_754

What relay would you suggest getting?  Obviously a 12V one but i've never messed with one before.  Any help?

CrossRoads

Something like this
http://www.mpja.com/prodinfo.asp?number=18474+RL
5V coil, resistance >=125 ohm so current is 40mA or less (5V/125 ohm = 40 mA)
Contacts that handle 12V & 450mA
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

dc42

Unless you need to isolate the 12v supply from the Arduino supply, I'd use a transistor rather than a relay - it will cost less, consume less power and be more reliable (as long as you remember to include a diode across the coil of the lock).
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

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