LOVE-O-Meter fails

Using Arduino Project Guidance
1

Hello There
I have been experiencing a problem with Project 03, LOVE-O-METER. I have been trying to troubleshoot the problem for 5 days but I am convinced that I have a defective hardware.

I have built the circuit and wrote the code as instructed in the Arduino Projects Book for project 3, pg 43. However my temperature readings are too high, 55-60C degree. I have compared and checked my circuit and the code many times with many youtube videos and with the project book and I did not find any difference.

For the sake of troubleshhoting I eliminated the LEDs section of the code as well as the hardware from the circuit and made the circuit to read only temperature which worked perfectly but once the LEDs are involved and start illuminating, for some reason they introduce extra voltage to the A0 on the circuit which creates additional voltage which leads to high temperature reading. I believe that my brand new Starter kit is defective.

Please let me know if anyone experienced the same problem. Not sure what to do with my brand new kit.

2

The ADC is ratiometric, i.e. the values depend on the reference voltage, which in your case is the Arduino operating voltage - should be 5V. If the LEDs lower that voltage, the temperature seems to increase.

Did you add the right resistors to the LEDs, and do you power the sensor by 5V?

3
4
5

Hello
I am doing the Love o meter project but my analog pin (A0) readinfg is too high(between 233-235) thus the temperature reading(around 62-65 C). I tried A1, getting the same reading. Am I doing something wrong.

6

Probably, but I have no clue what it may be without seeing what you have done and how you did it.

Post the code that gives the bogus results. Read the forum guidelines to see how to properly post code and some information on how to get the most from this forum.
Use the IDE autoformat tool (ctrl-t or Tools, Auto format) before posting code in code tags.

Post a schematic. Hand drawn, photographed and posted is fine. Or, how to make a schematic to post.

Are you using an Uno?

Do you have a DMM (Duigital MultiMeter)? What is the measured value of Vcc (the 5V power supply).

7

I see two big mistakes, no schematic and no code. Post a schematic showing all connections and your code following the forum instructions.

9

I haven't moved your topic but requested it to be merged with your old topic. Introductory Tutorials is for tutorials that e.g. you write, not for questions. Feel free to write a tutorial once you have solved your problem :wink:

10

Topics merged just to provide some background.

11

Do the LEDs also add voltage to the ground shared with your temperature meter?
You may measure with a DMM or by connecting an analog input to that ground and read it (should be 0).
In case it reads more than close to 0 you may have a bad contact in your ground wiring.

12

And now been troubleshooting your project (not the Arduino IDE) for two and a half years! :astonished:

About time you provided some actual description of - as gilshultz says, schematic, code, and (clear, detailed) photos.

13

Thank you all for the comments. Just a FYI: I am back to arduino after 2 years of break and started all over again. I didn't notice that I had the similar problem in the past. That being said reading your comments really inspired me. The problem has been resolved however If someone can explain the concept behind it that will be greatly appreciated.
I had the negative legs of the LEDs and the ground leg of the Temp36 sensor were connected to the same line on the breadboard. That was causing the problem. Moving the ground leg of the sensor directly to the ground pin on the circuit board fixed the problem.