Hello everyone,
i would like to control the rotation speed of 4-5 fan (12v 0.7a). How can i do this?
Moreover, how can i controls multiple devices (temperature sensors, fan, LCD...).
There's a limit with the Arduino uno I/O pins?
If yes, how can i extend the Arduino I/O capabilities?
Thank you very much
AmigaBlitter:
i would like to control the rotation speed of 4-5 fan (12v 0.7a). How can i do this?
Did you even Google? Lot of hits. But it depends on it you use 2/3-wire fans or 4-wire fans
AmigaBlitter:
Moreover, how can i controls multiple devices (temperature sensors, fan, LCD...).
By connecting them and writing a program that can handle all that. Hint, baby steps 
AmigaBlitter:
There's a limit with the Arduino uno I/O pins?
40mA absolute max, combined all 200mA. Better to stay under 20mA per pin.
AmigaBlitter:
If yes, how can i extend the Arduino I/O capabilities?
Loads of options. Shift registers, IO expanders, just using I2C/SPI devices, connecting it smart (for example multiplexing). Really depends on what you want. But remember, a lot of wires is also a lot of mess I mean problems uhm, work.
Thank you for the reply.
About the four fans: those are a 3 wire fans.
About this "By connecting them and writing a program that can handle all that. Hint, baby steps", i've put the question in a wrong way.
I mean, how many deviced can i connect to the Arduino 1?
Till now i need:
4 fans
5 temperature sensor
1 lcd screen
2 peltier modules.
1 piezoelectric
There are enough pin to control all these devices or should i extend arduino in some ways?
Thank you
3-way fans, use a transistor. I would go for a mosfet.
And about the devices, depends on the details. For example, each fan independent? What temperature sensors? If you take a 1-wire or I2C sensor you just need one set of pin(s). Lcd the same, what lcd? And for the peltiers (and depending on the type, for the piezo s well) use a transistor again.
18 pins <- would just fit on an Uno even keeping the Serial pins free.
10 pins <- More then enough pins on a Uno