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Re: Detector Building C

Posted: October 14th, 2019, 10:08 am
by YeagerTheCat
2. ADC: Arduino built-in ADC only 10 bits, too tight for 0.1 degree C, so plan to use 16 Bit ADC (ADS1115).
Isn't this not allowed, according to the FAQ?
(Section: 3 / Paragraph: a / Line: 1)
10/13/2019
MAY STUDENTS ADD A MODULAR ANALOG-TO-DIGITAL CONVERTOR (ADC) TO THEIRMICROCONTROLLER?

No. External signal conditioning board
My apologies if I am posting this twice - had some browser issues :-).

Use of a pre-bought signal conditioning board to attach up to the micro would certainly feel a like breaking the spirit of the rules. Putting something on a breadboard that the student assembles themselves (or however they did it), should be allowed. No one is specifying how you read an ADC value and if the student wants to do it differently, the should be able to. Again, using a premade thing that they didn't design/build, that is a reasonable restriction.

Re: Detector Building C

Posted: October 14th, 2019, 10:19 am
by kendreaditya
Use of a pre-bought signal conditioning board to attach up to the micro would certainly feel a like breaking the spirit of the rules. Putting something on a breadboard that the student assembles themselves (or however they did it), should be allowed. No one is specifying how you read an ADC value and if the student wants to do it differently, the should be able to. Again, using a premade thing that they didn't design/build, that is a reasonable restriction.
But the Arduino has an inbuilt ADC, think of it as upgrading the precision of Arduino's hardware

Re: Detector Building C

Posted: October 14th, 2019, 10:34 am
by YeagerTheCat
But that makes no sense. So if the student takes a little AVR and uses it on a bread board in place of the ardunio? If you use a TI thingy, and that uses 12bit, is that an upgrade tothe arduino? ADC isn't signal conditioning, it is the thing that reads a voltage :-) If they use a resistor in series with a thermistor is that illegal as signal conditioning? If they use an RC filter on the breadboard is that "external signal conditioning"? Using prebuilt/bought circuitry to get an accurate reading from a sensor - I totally get it, but if a circuit lab person wants to use an op amp to amplify it or buffer it … why on earth would you limit this.

I am assuming this isn't what they had in mind. It makes sense for student to be able to build a better detector, they just shouldn't be able to buy it and plug it in and on that front, totally get it.

Re: Detector Building C

Posted: October 14th, 2019, 11:12 am
by YeagerTheCat
I have posted a question to the FAQ to clarify for what it is worth.

Re: Detector Building C

Posted: October 14th, 2019, 6:20 pm
by jinhusong
1. Calibration Curve fit: thermistor with full Steinhart–Hart equation, 4 points. TMP36/M35: also 4 points to the 3rd degree of polynomial.
So in #1, you said "full Steinhart–Hart equation, 4 points", does the 4 points mean, input 4 points instead of 3? Because in my findings, I have discovered that it decreases accuracy.

Edit: It sounds like it shouldn't, but it does, I have no idea why
3 points are correct. I remembered wrong.

Still, I plan to let students to verify with at least 10 points after the fit. If fit not good enough, I plan to tell them go sections with the fitting.

Re: Detector Building C

Posted: October 14th, 2019, 6:25 pm
by jinhusong
I have posted a question to the FAQ to clarify for what it is worth.
Thanks for doing that.

Hope your question includes whether resistor and capacitor are allowed to add by students?

Tiger

Re: Detector Building C

Posted: October 14th, 2019, 7:05 pm
by YeagerTheCat
To start with it was just asking about the nature of the "external" circuitry and whether it is acceptable if student designed and produced (bread board or otherwise). 50 characters cramped my style :-)

Re: Detector Building C

Posted: October 14th, 2019, 11:06 pm
by Umaroth
To start with it was just asking about the nature of the "external" circuitry and whether it is acceptable if student designed and produced (bread board or otherwise). 50 characters cramped my style :-)
I also asked that, I had already designed and purchased my own PCBs for this and it would be quite irritating to not be able to use them

Re: Detector Building C

Posted: October 25th, 2019, 4:38 am
by YeagerTheCat
I got a response to my question, but it was in the form of an update to the thermocouple question. External student designed circuits are permitted given they are DIP components and breadboards … which isn't what we wanted to hear.

Re: Detector Building C

Posted: October 25th, 2019, 6:03 am
by Umaroth
I got a response to my question, but it was in the form of an update to the thermocouple question. External student designed circuits are permitted given they are DIP components and breadboards … which isn't what we wanted to hear.
ARE THERMOCOUPLES ALLOWED AS A LEGAL SENSOR AS LONG AS THEY COMPLY WITH ALL OTHER RULES? THERMOCOUPLES ARE LISTED AS LEGAL ON THE EXAMPLE SENSOR LIST ON THE SOINC.ORG WEBSITE BUT NOT EXPLICITLY LISTED AS ONE OF THE TWO FUNDAMENTAL ELECTRIC COMPONENTS

Yes. Thermocouples are legal with student-built circuits constructed on breadboards made with fundamental components and/or DIP packaged integrated circuits (ICs). However, external circuit boards are illegal. So, a thermocouple may be used, but an external signal conditioning board cannot.
I think what it is saying is that thermocouples are only legal on those two things, but it's not expressing limitation on other circuit boards, hence why they crossed out "However, external circuit boards are illegal. So, a thermocouple may be used, but an external signal conditioning board cannot." I hope I'm right, because I really don't want designing and ordering those PCBs to have been a waste of time and money.