Hey So i have a rather basic question in regards to 5v relay modules.
Basically what i would like to know is the following,
Can i turn on the relays without an arduino, aka run 5v through separate switches to independently turn on each channel of the relays.
Next would be about the 240v power i had running into these relays to turn on Some devices i want to control. I would need a “2 module” relay to turn off both “hot” wires correct ?
You can always turn relay on without Arduino. You just apply necessary voltage to its coil and it will ‘click’. The thing with Arduino is that its max current on the output pins is around 20mA, and relay coils usually have values bigger than this. So, in order not to burn the Arduino output, relay modules are made ,which have integrated transistors or optocouplers to safely connect coil to Arduino.
Yes, I module, with relay, has 1 NC (normally closed) and 1NO (normally open) contact, so you would need 2 module relay to turn off 2 wires, for example this one:
As @igor_X stated you don’t need an Arduino to power the relays, you can simply supply 5VDC to them.
And you are correct, for turning off both hot wires you will need a 2 channel relay like this one or a DPDT relay like this one that is more robust but requires a 12VDC power supply, you can find many other options here.
You should also keep in mind the current consumption of the devices you are going to use because those relays will be able to handle up to 10A.
