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Basic Electronics » Some questions (temp sensor + button)

June 05, 2010
by Kafke
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I have followed the pdf guide to the end with the exception of the dip switch tutorial.

When I completed the temperature sensor tutorial, I noticed that it was accurate, but it said it was 5-6 degrees higher than what it actually is. Why is it only 5-6 higher and how to I fix it without just saying "temp_avg-5;"?

Also, I didn't see any tutorials on how to use the included speaker, but after messing around with it, I managed to make a small "tick" sound. Is that all it does?

And third, The button was not explained at all. It looks like it won't even fit on the breadboard. The pins are unaligned with the holes on the board. Should I just push them into place?

Other than those three issues, I have been having a blast with my Nerdkit. I even managed to make a power switch :D

Please upload a tutorial on how to use those two parts.

Oh! and one more question. During the temperature sensor project, I noticed a couple other pieces included in my nerdkit that looked like the sensor just with a different number on them. What are these and what are they used for?


June 06, 2010
by mongo
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Those other things that look like the temp sensor are field effect transistors. (FET)

As you progress, you will see some projects where they are employed. They act much like a switch in a circuit where the NK MCU might have some trouble. There are other discussions in the forums about the FET's and other info on using them so I won't go into too much detail or repeat it all here.

Happy hunting.

June 06, 2010
by Rick_S
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The temperature variation can be caused by variance in the component itself (allowable tolerance) or the voltage being supplied to the device in relationship to the reference voltage used and formula in the program.

The push button switch (I assume you mean the one with the blue/green body and red button with 3 leads) can be forced into the breadboard -- I didn't do that with mine because I was concerned with permenantly damaging the 3 positions it was forced into..

And as mongo said, the 3 legged device (2N7000) is a MOSFET.

As for what they are used for, take a look through the various projects in the tutorials section of the website. You will find controlling motors with the MOSFETs and using the push button (as well as your piezo element 'speaker') in the Morse Code decoder.

Some of the tutorials are documented better than others but if you get stuck or have questions, there is usually someone here that will pop in and help out.


June 06, 2010
by Kafke
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Thanks for the help.

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