Adron, or anyone, how would you go about giving your PC the ability to constantly read the temperature nearby, say within 5-10 feet.  I want to put a thermometer on my desk cubicle wall and record the temperature over time into the PC.  From there I can keep the temperatures in a database and can handle the graphing.  I just don't know what to buy and do to get the temperature input.

Here is a rather large list: http://www.maxim-ic.com/pl_list.cfm/filter/11

Here is something that looked promising from that list:
http://pdfserv.maxim-ic.com/en/ds/DS1720.pdf

It's on my todo list to make a thing for Arta that does approximately this.

I bought the components but I haven't gotten around to making the pcb and soldering it together. I'm going with a microcontroller with  A/D inputs, an op-amp and a thermistor.

It will just hook up to a serial port and transmit values continously.

You could also buy something ready-made. There are ready-made thermometers with digital output connections. As well as ready-made A/D boards or boxes with output to a computer. I just like messing around with it myself...


Also, I'm going to try making USB peripherals sometime, I've seen a really nice chip for that.

What sort of parts would I need?

[url]http://www.maxim-ic.com/Sensors.cfm[/url] has some thermal sensors, but I do not know which to select.

Where do I acquire a PCB suitable for hobbyist soldering?  What about power?  I would like to run this with a AA or AAA battery, unless that is overkill.  If the USB port can supply power, that is even better.

Hmm what do you think of ... [url]http://natan.zejn.si/electro/tempmeter/[/url] ?

[quote author=Grok link=topic=10119.msg94376#msg94376 date=1104931089]
What sort of parts would I need?

[url]http://www.maxim-ic.com/Sensors.cfm[/url] has some thermal sensors, but I do not know which to select.

Where do I acquire a PCB suitable for hobbyist soldering?  What about power?  I would like to run this with a AA or AAA battery, unless that is overkill.  If the USB port can supply power, that is even better.

Hmm what do you think of ... [url]http://natan.zejn.si/electro/tempmeter/[/url] ?
[/quote]

That one requires real-time access to the serial port. You have to accurately measure the charging/discharging time of that capacitor. It probably won't work well under Windows.

If you want to keep it simple without any programmed component outside the computer to generate a nice serial data stream or something like that, perhaps a PWM signal (pulse width modulated) would be the way to go. You sample a digital input as often as you like, and the temperature is proportional in some way to the percentage of samples with a high value.

From the maxim page, this sensor looks good, except that it is in a surface mounted package. Very hard to connect to something as a hobbyist. You would want components mounted through holes. Otherwise, that one + a ~5 V zener diode + a resistor of around 10 kohm + a capacitor of say 10 µF could otherwise be directly hooked up to the serial port and used to measure temperature. No external power supply would be needed, the serial port can supply 1-2 mA.

This is an alternative that is easier to mount. I'd get the one in the TO-92 package. It would also require the zener diode, resistor and capacitor to generate a somewhat regulated voltage from the serial port.

Regarding circuit boards, you typically use something like this to try out your project until it's working right. Then you either produce a PCB using an UV box and some etching, or you use something like this to solder it on. I typically use ones with just a grid of holes covering the whole area, with copper lines connecting them horizontally all the way, but there are many alternatives.

Also, for a simple project like this with only four components, I might just solder it together without any circuit board at all.


Btw, are you more interested in measuring the temperature or more interested in building something?

More interested in measuring the temperature.  But if it's easy to build, and does not require I remember much electronics, maybe I could have some fun too.

Hehe, k. Well, does the pwm technique seem reasonable to you? Do you have a free serial port on that computer?