Arduino Uno as a SMD tactile push switch.

Hi

I have kitchen fan with 3 button:

  1. On/Off (one press "on", second push "off")
  2. "+" (Press once, fan go faster)
    3 . "-" (Press once, fan go slower)

Can i solder wires directly to those SMD tactile push switches and connect them to Arduino Uno with 433 MHz receiver and control it with remote or i need extra module or shield?

Depends what voltage is on them. Probably safer to connect a relay across them and have the Arduino close the relay.

What max voltage is safe? and more important, is possible too short 2 pins for 500 ms?

5V.
Can connect two inputs, or an input and an output, for as long as you want.
Two outputs, do not connect.

Two button pins, probably as long as you want.

Thank You for yours time.

My first Aduino coming tomorrow, I will learn how to use it and then i will try it if it will work I will post here.