Hi,
I’d like to be able to read the temperature in a room into a PC, and then monitor and graph it. I should be ok with the coding side of the project, but I’m an electronics novice, so would like to ask a question about the other side of a K8055.
In this post:
forum.velleman.be/viewtopic.php? … 2e14114b1e
Nickm says he was able to “connect a thermistor across inputs 1 and 2”. Is getting the input this simple - can I just buy a thermistor, attach it to analog inputs 1 and 2, and then read the analog level? No additional components required? No power supply?
If it is this simple (!) could someone recommend a thermistor which would do the job please?
I’m aware that Velleman supply a kit for temperature sensing (K8067), but like I mentioned, I’m an electronics novice so attaching one thermistor would be much simpler for me than trying to figure out how to connect and power the sensor.
Thanks for any suggestions,
Tom
One alternative may be this:
velleman.be/es/en/product/view/?id=12368
You need also a 10k resistor.
Connect the NTC thermistor between A1 input and GND.
Connect the 10k resistor between A1 and +5V of the K8055 board.
Remove jumper from SK2. (You’ll get the +5V from the other pin of the SK2 pin header.)
Then you have to put a table to your program to convert the voltage to temperature. The voltage over the NTC is very non-linear vs. temperature.
See “THERMISTOR RESISTANCE” in this link to get the resistance in different temperatures: ecircuitcenter.com/Circuits/ … model1.htm
That’s great - thanks for not only the reply, but also such replying so quickly!
I’ve ordered everything I’ll need now - hopefully I’ll be able to come up with some software which might be useful to others. I’ll post back here when I’ve worked on the project in any case to let anyone following in my footsteps how I got on.
Thank you!
Tom
You can also use the K8067/VM132 temperature sensor. It has been designed to work with the K8055
http://www.velleman.be/ot/en/product/view/?id=354616
The project worked out ok - I was able to connect the components just as you said, and it wasn’t tough to get readings from the sample C++ code you supply.
The thermistor is very sensitive - you certainly need to smooth the output across time. It’s also got few values for measuring room temperature - one integer read from the DLL can represent quite a wide range of temperature - more than 1oC.
Thanks again for your help!
Tom
hi stickyman, i was interested reading your post about displaying the temprature measured from the anolog input and displaying it on a line graph, i have been trying using vb 2008 with no sucsess can you help ??
Hi davejay,
That last post I wrote could probably have been better put:
“Although I got all the components and code to do something … it didn’t seem to be at all reliable, so acknowledging my lack of understanding, I put the electronics in an actual drawer and the code in a virtual drawer and forgot about it”.
Oh dear…
About as useful as I can be to you is to supply a VC++ 6.0 project which will read values from the DLLs supplied, but the values didn’t really seem to correspond to reality. I write a function like this:
double CFlossyDlg::Convert(long i)
{
switch(i)
{
case 53: return 25.1; break;
case 54: return 25.1; break;
case 55: return 22.9; break; // 23.6
case 56: return 21.9; break; // 23.2
case 57: return 22.4; break;
case 59: return 19.1; break;
case 60: return 19.1; break;
case 61: return 18.9; break;
default:
return 0;
}
}
This is trying to convert from the value I was reading from the DLL/USB port/board/thermistor to a temperature, based on a digital thermometer next to the kit.
So, if the project could help then sure, and if you have C++ coding questions then perhaps I can help, but otherwise I’m not sure I can really assist you 
Tom
thanks stickyman 
i tried using ntc termistors as well and had erraric readings, i ended up buying a k8056 theromstat for bout £10 that works really well and i am pleased with, it was easy to put together ( i have a little exp. with soldering, but an easy circuit to follow )
i have also managed to write a little vb 2008 code to display the temp. in numbers and 5 coloured blocks that light up a little like a thermometer, i dont have the first clue about how to get the graph to work ( yet ) , i think i might have to make a datbase and do …i dont know. i just dont know aarrrrggghhhh !! this codeing aint easy…
thanks for your reply and code example, sure look different from vb,
