I need to power a light bulb or something like 110 V or 220 V at normal amperage for TV or something at that range like a fan...

My micro-controller is an Arduino with 5 V out and 12 V max out trough transistor switch.

To my understanding a stepper motor drive could be a viable option to enable the relays... I can even control current, right?

Up to 8 channels

Could this work better?

  • 1
    Just remember SSRs are not good with fluorescent light bulbs as there is a small current through the relay in closed state.
    – KIIV
    Oct 17, 2016 at 6:44

3 Answers 3


Which to use where

Ok, so I've narrow the 2 main choices that you have : either a MOSFET or a RELAY. For higher voltages, it is much safer to go with a relay but for higher current, you might as well use a power MOSFET.

Option 1 - Relays

They are mainly used to control already made stuff like a bulb using main's voltage. They are also used to control stuff like a fan (pre built), lamp, and many more. Relays are also simple to wire and don't quire much electronics skills. The main disadvantage of a relay is that they are not as good as MOSFETs when it comes to current handling.

Advantages: Light bulb, stuff bought from the sotre (TVs, fans, small heater), house automation, laundry, house heater, fridge

Opition 2 - MOSFETs


MOSFETs are great when it comes to kick some voltage in to your devices. I remember as a kid, I use to stock these in NERF guns. Motors will instantly start with MOSFETS!. For even higher current control. Try power mosfets, they are designed for high current. Also know that mosfets are bad in the way that they tend to warm up a lot (if the current is high).

Advantages: Neon light, motors, things that need to be responsive (drone motors), things that need to be precise (PWM)

In conclusion, relays master the world of high voltages and MOSFETs the world of high current!

  • MOSFETs have an intrinsic body diode between source and drain. You want this diode to be reverse-biased when the MOSFET is off. Hence MOSFETs are not good for switching AC, and mains is AC. Oct 21, 2016 at 8:58
  • Well thats why I said that Relays are better for mains voltage. Shoud I modify anything?
    – Dat Ha
    Oct 21, 2016 at 11:37
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    Yes, make it crystal clear that a MOSFET is unsuitable for switching mains. It is absolutely not obvious from your answer as it stands now. Oct 21, 2016 at 12:09
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    Quick link : youtube.com/watch?v=LLFQ8sBWc80. He uses a cheap 2-channel but a 8-channel should work. See how he does it and follow CAREFULLY. I can't insist on safety with relays!
    – Dat Ha
    Oct 22, 2016 at 11:44
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    So, yes you can use the one from the link that you provided.
    – Dat Ha
    Oct 22, 2016 at 12:05

You can use a 5V Solid-State Relay module to control light bulbs. They cost $4-6 from US-based suppliers and $1-3 from a Chinese supplier. Just hook up the supply to the center pin and the load to either the NO or NC pin. Supply 5V to the module and wire a digital pin to the module to control it.

  • Nice one and thanks but could you confirm if any of the ones I found on ebay works as well?? Check my edit
    – DarkXDroid
    Oct 17, 2016 at 4:01
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    @DarkXDroid The seller did not include part numbers or manufacturer names so I couldn't lookup any datasheets. A relay with a max 250VAC and max 10A rating will be able to handle any standard light bulb. The main concern is how much current is required to trigger the relay. Arduino I/O pins can only supply (or source) ~20mA so if the relay draws more than that it will damage the board. The relays in the link might work but you can't know for sure without the datasheet. I know that Sainsmart relay modules are safe to use with Arduino digital pins.
    – zdub
    Oct 17, 2016 at 4:33
  • I got ´´Omron 5V solid state relay 240V 2A, output with resistive fuse 240V 2A?´´ I think itś not enough so I´ll search for 250vac with an 10A, right?
    – DarkXDroid
    Oct 17, 2016 at 5:13
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    @DarkXDroid I was about to say transistors or better: mosfets. A mosfet is a good way to switch with Arduino because mosfets require voltage and not current to switch. Many mosfets are designed to trigger between 1~3 volts. You can then supply 5V from the Arduino 5V pin (which can give up to 1A current) and use that to switch the relay.
    – Len
    Oct 17, 2016 at 9:31
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    @DarkXDroid I don't know about that. Never used a motor driver like that. I'd stick to mosfets.
    – Len
    Oct 19, 2016 at 9:40

The first one you have seems fine (in my opinion). Note though that relays are something not to be cheap with. They can cause dangerous accidents if you buy them from a cheap supplier (chinese). I'll always go for a local supplier (don't know where you live so I can't tell). Make sure to check Radioshack and stores like that.

Also make sure that you find one with a datasheet. No datasheet = no specs. No specs = you don't know the max of your relay which is BAD. The max of a relay should be known and respected or something bad can happen.

  • First or second option? I understand that low grade equip can cause a disaster but I already have a solution... besides this is prototyping and I want to understand the technology and limits. That why I put a range devices that I could control. But you got a valid point with security and end capacity
    – DarkXDroid
    Oct 17, 2016 at 16:54
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    first option is the one that i prefer
    – Dat Ha
    Oct 17, 2016 at 17:06
  • I´m grateful for everything .... I´go with that at first
    – DarkXDroid
    Oct 17, 2016 at 17:16
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    In my experience, the relays purchased from a local or US supplier are all made in China anyway. Oct 20, 2016 at 17:23
  • My exp tells me the same lol the thing is that I should pay more to stay on the safe side
    – DarkXDroid
    Oct 22, 2016 at 7:52

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