Cheap Hot Air Station With Arduino

first , it's my first instructable and i'm not native in english so be gentle

I had an idea weeks ago , build a hot air station for cheap , very cheap , i don't need a big stuff just a little station for few soldering.

i've find on ebay the 858 hot air station but to expensive for me, so i just buy the handle for 8 euros! and i have built a circuit with a arduino to control this handle.

lets go!

The handle comes with 8 pins:

2 wires for the heater , it works with 220v ac ( i dont know for 110v) it is the grey and the white wire.

2 wires for the 24v dc fan plus is blue ans gnd is brown

1 wire for the reed switch the green

1 wire for the earth the yellow

2 wire for the thermocouple red (plus ) and black

now how to control this?

i will separate in section the rest of the project

first the heating

the objectif is realy simple : start and stop the heating with a logic command of 5v .

But we can't do that with 220 vac easily the solution : a triac and an optocoupler,

tric is like a relay but static , it is control by an optocoupler to secure the rest of the circuit.

it is done here with a moc3063 and BTA140-800

the fan works with a 24vdc, it must be activated always when the gun is hot .

we have two commands: the first is to power on the fan with the arduino it's a simple transistor . the second is a potentiometer to control the speed .

note: here the components are not the best, i take what a had in stock and it works great!

the arduino nano control all the things,

to measure the temperature i used a module with a max 6675 connect directly to the thermocoupler of the handle,

the max6675 is connect by spi to the arduino and the supply library is very simple to use.

I put 2 push buttons to control the temperature and a lcd , the lcd is control by i2C it's overkill but i only had this in stock so i used it!

there is a led wich is lighting when the heater is on

to conclude the arduino is connect to my card build earlier.

My code is the simplest possible:

first: i don't implement for the moment the reed use when you put-on the station the gun is always on!

then we read the temperature if it is lower than the consigne the heater is put on , and stop when it reach the goal !

with the two button you adjust the temperature.

that's all.

Off course it's not perfect but i thought it would be a good starting point for all the beginner in electronic.

what's next?

in the future i would like to add the reed switch support , ( i've ordered in china the handle support) and most important the pid for the temperature management,

if you'd like to implement fonctions please be free and contact me , i will be very happy to test it!