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DIY Digital Thermometer

Step 2Circuit

I tried to make the circuit as simple as I could without over complicating the program.

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3 comments

Oct 31, 2009. 6:00 AMLivyo says:

It's work whit an DS18B20 sensor ?

Jun 23, 2009. 12:58 PMcircuit_question says:

I've been trying to build this circuit and I had a number of questions. Does a ATMega8L work? Do you need to program this? I was wondering what "This part is optional" meant? Does this mean connect all of this together? I was trying to order the KTY-13-5 temperature sensor. The KTY135 surface mount temperature sensor kept popping up. This is extremely small and hard to use. Do you know of an equivalent sensor that is much easier to use? What does the Vcc arrow connect to from the diagram? What does GNDIC1 mean? And as for power, is 1 positive? I'm excited about this project. I'm hoping to get it to work. Any help would be much appreciated.

Jul 2, 2009. 3:13 PMDemonDomen (author) says:

I think that a ATMega8L should work and yes, you need to program it.

That optional part is for connecting a programmer, so you can program it.
I didn't mark the pins in the schematic, but they are like this (from 1 to 5): POWER, MOSI, MISO, SCK, RESET, GROUND.

The pins above are the pins from the programmer. I personally use the STK200/300. You can also buy an avr ISP programmer.

I know the sensor is surface mount. When I ordered it, I didn't know. Luckily I managed to solder it. I guess you could use any sensor of the same family. Check the datasheet, there are more models inside. They all change their resistance with temperature and use the same formula to calculate the temperature. The only thing you might need to change is the resistance at 25°C (it's in the source code (i think the name of the variable is r25)).

It was not the best idea to add both the power symbols and plugs into the schematic, it only makes it confusing. The Vcc arrow is supposed to indicate that a 5V power supply is connected to that wire. The GNDIC1 is normal ground (eagle named it like that).

Yes, pin 1 of the plug is positive.

I hope you'll make it. If you have any trouble, don't be afraid to ask. If I don't answer in a while, write me a PM.