Choosing Relay for 5V DC & 12V Motor

[TheRedDevil18]

I have a 5v dc circuit and a 12v dc motor. If I had to use a relay, when looking at the specifications, what do I look for ?, will the coil voltage be 5v and the switching voltage be 12v ?

Will these relays work ?
http://www2.mouser.com/Electromechanical/Relays/_/N-5g31?P=1z0x3tdZ1yyfbg3

Also, how do I know the minimum current required to activate the switch ?

 

[Hesch]

will the coil voltage be 5v and the switching voltage be 12v ?

Yes.

how do I know the minimum current required to activate the switch ?

By activation the current will be
I_coil = V_coil / R_coil
However you may insert a save resistance in the circuit, decreasing the coil current when the relay has been activated. Often this save resistance has already been included in a relay with a dc-coil.

Also you should protect the NO-switch ( the righthand in the attached ) by means of a RC series connection. Otherwise you may "burn" the switch, breaking the dc-motor current several times. The values for the RC depends on the motor current and how fast the NO-switch will open.

 

[TheRedDevil18]

Ok, I want to connect an LED to show when the relay is on, but because the LED drops 1.7V I would have to connect the relay in parallel so as to receive the full 5V supply voltage

Here's a schematic

Would this connection be fine ?

 

[wirenut]

Also, usually when you have a relay coil you insert a reversed diode across the coil to absorb the voltage spike when the coil shuts off.

 

[Averagesupernova]

Also, usually when you have a relay coil you insert a reversed diode across the coil to absorb the voltage spike when the coil shuts off.

Not only could you damage the transistor when left out, in this case you could damage the LED also.