I am automating my room through IoT, I require an 8ch relay for my room, so when I went to buy em I saw that there were 3 types of them (5v, 12v, 24v). What is the difference between these 3 also which one is the best?
These voltages refer to the voltage required by the relay coils on the PCB.
No one voltage is better than the other.
Which ever PCB you buy, you need an external power supply that is the same as the relay coil voltage.
if you buy a 12v relay PCB you need a 12vdc power supply
if you buy a 24v relay PCB you need a 24vdc power supply,
If you plan to switch mains voltages, try to get an opto-isolated relay board.
Do you really feel comfy messing with dangerous mains voltages?
Thanks for helping me my mates <3