Mosfet selection

Hello everyone,

Forgive my ignorance, I have a great deal of confusion over mosfets, I have googled the subject and looked at sites that explain the datasheets, I have searched this forum and not really found the answer in terms i could understand.

GOAL: I'm trying to have my Adruino Uno rev3 using motion sensor(s) to turn on 12v (0.5-5 amp) LEDs in a staggered manner such that the closest one to the sensor comes on, then the next closest 3-8 seconds after that and continue down the line (9x). until they are all on and then they would go off after a delay in the order they came on.

I believe I have the sketch properly written; still waiting on parts to confirm it works but the compiler does verify, I can figure out the code myself (I think). But I am having trouble finding the proper Mosfet, I chose Mosfet because of the cost I'm trying not to spend too much on this project as it's just kind of a learning exerciser for me. I just got my adruino about a week ago and I don't have the sensors yet but I have a button for testing. Also I have more time than money right now. I tend to order parts from China and just wait for them to come in (4-6 weeks). So I really want to get the proper component to avoid this dragging out for months and months.

I have digital pins 3-12 feeding the signal to open the mosfet gate, from the info i have managed to gather on my own I think the Mosfet I need is:

"IRF520N IRF520 TO-220 N-Channel"

at a cost of about $0.30 each (shipped from China) and I would need at least 9 for my project and don't mind having some spares. Then anything over 1 amp would require a heat sink (I have been collecting heat sinks from old computers and such so I have them around).

As I understand it I would use the mosfet gate to open the ground to complete the circuit?

Any suggestions on the proper Mosfet would be appreciated or if I am going at this in a backwards/sideways manner, I am open to criticism/help.

Thank you for your time

The IRF5*0 range is often used because they are cheap, but to fully turn them on you need to supply 10V to the Gate (which your Arduino obviously can't do). You want what is called a 'Logic Level' MOSFET, which turns on fully with 5V at the gate. A good choice is one of the IRL5*0 range, you can even get an IRL520 if you'd like.


Thank you.

For whatever reason the IRL540n is cheaper on Ebay? I assume it would work as well?

I found some IRL520nstrr (surface mount but I think I can make it work I'm fairly good at soldering) pretty cheap and from US but I'm not sure if I am missing something.

Appreciate the help with this, I am usually able to find the answers I need through research without posting but mosfets are not clicking internally for me.

No that's all good, it is a subject that is worth learning about. I'm certainly no expert but I've been looking at it a fair bit recently for a project. The IRL540 would be fine, I've used it in the past.