arduino and multiple thermo sensor

hello,

I am projecting a kind of woodstove controlling system.

After designing my plan, I realised that I need 18 diff thermo sensors ( K or tmp35)
This quite too much for one arduino uno v.3 as there are not enough analog.

Anyway I cannot believe it shouldn't be possible to do so.

I am not an expert ( far from ), but if something like a multiplexer should be the solution...

if somebody could suggest me a kind of easy solution, it would be great,

thanks,

Philippe

If you are using a K-type themocouple you will need some kind of conditioning amplifier anyway. You can get one with a digital interface (I2C) and use an I2C multiplexer if the units don't have adjustable addresses.

For any temperatures below 125°C you can use a string of DS18B20 OneWire thermometers on a single pin. Each has a 64-bit unique address.

thanks for your reply,

For the K sensors, I intend to use a RC and OAP.
Your idea to convert into digital sounds nice, I will investigate with I2C
I've found 'Analog/Digital MUX Breakout' on SparkF, with 16 AD ports which seems to be very easy to use. ( still missing two AD ports but I can use those on the UNO, so my problem seems to be solved at this time.

regards,

Phil

Why don’t you use a digital sensor, like DS18B20?

Good point,

because I already bought the K-type and tmp36 :wink:
but you are right dig sensor should have been better.

thanks,

Phil

...
also, I am not 100% sure that with a woodstove, 125° is sufficent, it MUST but sometime water may boil and reach xxx ° before exploding the tubes.
One reason to create this controlled woodstove.

Just for expl.

woodstove is a non interruptible process. I need to spread the hot water following a prioritised route. But when reaching all the thresholds ( heating circuit, buffer tank and sanitary hot water) where can I divert the excess of t°?

Thanks to these proj. It will advise ( my wife or me ) to stop loading wood BEFORE or to load more,

regards,

philbona:
woodstove is a non interruptible process. I need to spread the hot water following a prioritised route. But when reaching all the thresholds ( heating circuit, buffer tank and sanitary hot water) where can I divert the excess of t°?

You can control the wood stove heat output by controlling the rate it receives oxygen. You can close the dampers to reduce heat and blow in air to increase heat.

oulala,
new item in my project,
oxygen control ? yes i will investigate
blowing or reducing the air input ? wouh, it's a very basic woodstove,
only manual intervention is possible to reduce the ventilation, otherwhise putting new diy mechanism on it and...
my wife will be ...
I don't know how you say that in USA,
Hmmmm,
say strange

phil