Good day! i need some help from you guys.
I'm planning to make a home automation, to light fans , lights aircon etc. via bluetooth
what relay should i use?
thank you in advance
Good day! i need some help from you guys.
I'm planning to make a home automation, to light fans , lights aircon etc. via bluetooth
what relay should i use?
thank you in advance
What power supply do you have? Both sorts of relays will work and both need a transistor to drive them, there is nothing in it.
12v relay would generally draw less current compared with a 5V one... but it also depends on the availability of power supply. Sometimes current consumption is important if the power supply is far from the controller. This is sometimes true in building automation projects where dc power is distributed eg along cat5 cables
I think 5v is better in this case.
More importantly... know the current of the load being switched. That will make sure you have relay switch contacts properly specified.
If you might possibly switch up to 5 amps at house mains voltage, buy a 5V relay with 110/220 8 to 10 Amp contacts. You never want to use a relay in conditions that come close to it's marked contact ratings.
jean_howard:
I think 5v is better in this case.
Very much the opposite.
You generally want to consider 5 V as your "logic" power supply. Since you must switch your relays with transistors (or FETs, or a TPIC6B595), powering the relays from the "raw" 12 V supply from which your 5 V supply is regulated is more consistent with isolating the relays from the logic supply.
The commonly available opto-isolated relay modules, correctly wired, are rather useful for this.