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Topic: newbie and scared to blow things up :) (Read 901 times) previous topic - next topic

massib80

Hello!
I've received my UNO today and I was passing the last 20 minutes on make different LED blinking… it works!  ;)

Now, I've a crappy digital thermometer from which I'd like to steal the wired outdoor temperature sensor.

1. Being a total ignorant in electronic I'd like to ask how can I know the voltage required form the sensor? (in order to avoid to blow it up)
2. How can I identify how to hook it up in a breadboard? The issue is that this sensor has only 2 pins, while all the temp sensors I see on the internet have 3  :smiley-roll:

This mini project it's all what I want to do to start hacking crappy gadgets and gain experience with the Arduino… the final goal will be a home made satellite… guess it will happen in a while…  :smiley-sweat:

majenko

What you have there is most likely a thermocouple.

These give tiny voltage fluctuations according to temperature changes.

They're not easy to work with.

You really need an interface chip - I got one to play with a bit back, and I wrote up about it here:

http://hacking.majenko.co.uk/thermocouple-interface

massib80

:smiley-eek:

I thought was just a matter of some resistor and then being able to use it…

Well… thank you so much for your reply, you saved me from cannibalize the sensor without then being able to use it…

I thing then that the best it's just buy one of those 3 pin sensor, are those better/worste then the type of sensor I have now?

I suppose the one I have now is a good one for "external" sensor hocked up to a long wire…

majenko

The "3 wire" ones - like the LM35 and such - are far far easier to interface with the Arduino.

You just provide it with power and ground on 2 pins, and the third pin gives a voltage relative to the temperature, which you can measure with an analogue input.

DVDdoug

You are unlikely to damage the device by connecting anything un-powered, or anything powered by 5V or less to the input.

It would be a LOT easier if you buy a temperature sensor so you know what you are working with and you can look-up the specs and application notes.

Quote
(in order to avoid to blow it up)
It happens... :(   We all blow something up once in awhile.   With cheaper logic chips & op-amps you can buy extra parts.    With microcontrollers, we try to be careful and stay lucky. 

Things get burned-out with excessive voltage or excessive power/current.    If you have not done so already, take some time to learn Ohm's Law, which defines the relationship between voltage, resistance, and current.   You don't need to memorize Ohm's law right now, but you should understand it and be able to look it up, in case you are connecting something and you want to make sure you not going to "pull" too much current out of your Arduino and burn it up, etc.

Common ways to burn-out a device:
- Static discharge (from touching the device without grounding your body).
- Connecting the power supply backwards.
- Too much voltage on the input (or too much voltage on the power supply or any pin).
- Shorting an output to the power supply or to ground.  (It's generally OK to short-out an input.) 
- Connecting a load with too-low of a resistance to an output, which draws excess current.
- Connecting two outputs together.    (It's generally OK to connect two or more inputs together.)

jwatte

Look for a ruggeduino if you want protection against those! $35 online.
Note that the AVR has static protection built in on each pin.

massib80

Thank you guys!
I'm pretty impressed with this forum, thanks for your answers!

I'm reading as well "electronic for dummies" and try to keep my self to rush too much…

I'm waiting for a breadboard and then I'll go to a local supplier to buy some led, resistors and the like… so that I can start to experiment a little!

Here you soon from me then!  :smiley-roll-sweat:

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