ON / OFF switch with separate power circuit

Projects General Guidance
1

Hi.

Is it possible to controll only a switch without having the power circuit through arduino? That it gets power from grid/powerline, but arduino is controlling when it should turn on and off?

Here is a picture of what I mean if my description is unclear:

thanks in advance!

2

Is the fan mains powered? If so, a relay (mechanical or solid state) would be easiest. Google 'arduino relay driver' to see the circuit. Check Sparkfun or Adafruit for relay boards with built in drivers and solid state relays.

3

go0fy:
Hi.

Is it possible to controll only a switch without having the power circuit through arduino? That it gets power from grid/powerline, but arduino is controlling when it should turn on and off?

Here is a picture of what I mean if my description is unclear:

thanks in advance!

Take a look at this

Is this something like what you want?

I did a experiment hooking up 3x 12V fan's to a thing like this controlled by the arduino, with a LCD display with buttons so i could turn on and off fans, monitor temprature, set stepps on speed of the fans to run faster or slower or just have the speed depending on the temprature.

4

You could use something like the PowerSwitch Tail.

5

groundfungus: Yes, the fan is plugged in the wall outlet and getting power from main grid.

Mr_Supportman: Isn't the power going through arduino?

JohnLincoln: thanks, looks what I need.

6

go0fy:
Mr_Supportman: Isn't the power going through arduino?

Nope, you have to have common GND but the arduino PWM pin is only comunicating with the Tip 120 to tell it how much current to feed your fan, and in your case that would be 0 or 255 ( off or on )?

But if you want the same grid to supply power to the arduino allso thats easy aswell.

7

Yes, the fan is plugged in the wall outlet and getting power from main grid.

You cannot use a transistor to control mains power! The power switch tail is the safest way to control the mains powered fan (off and on, no speed control). Controlling a mains powered fan speed is a whole different problem.

8

Thanks for answers!

As long I can turn fan on and off I'm happy. The Speed of the fan is unrelevant in my case.