Now in terms of building something to do a simple task like this, that makes no sense at all. The smallest practical unit to implement a microprocessor control for something is an Arduino Pro Mini. It has all the necessary support parts on it, directly wired for programming with a cheaply available USB to serial adaptor.Yes, there are also some other modules using the ATtiny and such, but frankly, no cheaper than a Pro Mini from China. However, trying to assemble the parts yourself from scratch - a futile exercise.
I try to use IRF530N and connect it to pin 3 of Arduino but after that, it just gives me about 3.75V on output and then I try to increase it but it was so slow and just go up about 4V.
That's because that's not a logic level MOSFET. See data sheet... it won't open properly at 5V VGS.Try e.g. the IRL530 (or another IRLxxx) instead. The L stands for "logic level". Those will open properly with 5V signals. Look for a value for RDS, ON for VGS = 4.5V. If that's not given in the specifications, it's not suitable for use with 5V Arduinos.
Find what other MOSFETs your supplier does have on hand. Read the data sheets; see which ones are logic level. Buy a few of those.Find other sources - are vendors like RS Components, Digikey or Mouser not active in your area?
That does not make sense at all. You need to illustrate how you have attempted to connect it. I suspect a gross blunder.Figure 2 in the datasheet (you did say an IRF530, didn't you?) suggest that drawing 2 Amps at a gate voltage of 4.5 V would result in a voltage drop of about 1 V and it would dissipate 2 Watts - and need a small heatsink. But it would still work satisfactorily.
Where are you located, country and maybe city? Maybe there's another option!
Hi,Are you showing us a speed controller that already comes with the fan?If so why not just parallel up the existing speed up/down buttons with another set of buttons and place them where you need them?Tom...