Detector Building C

nicholasmaurer
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Re: Detector Building C

Postby nicholasmaurer » October 25th, 2019, 8:42 am

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.
I believe the intent of this change/update is to reflect that students can use circuitry outside of their microcontroller, but that it should only be constructed from "fundamental components and/or DIP packaged integrated circuits (ICs)." If you self-designed a PCB I do not think that will be a violation of the rules.
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kendreaditya
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Re: Detector Building C

Postby kendreaditya » October 27th, 2019, 8:02 am

I am just confused why they crossed out "external signal conditioning board cannot", which implies that you can use the board. But in another question, they state "External signal conditioning boards are not allowed". So are we like allowed to use them or like not. If not, then all the good teams are going to invest in a board that has like a 14-bit ADC, so like what's the point?

In this article (https://www.jameco.com/Jameco/workshop/ ... stors.html) it says that adding a fixed thermistor makes the resistance graph linear. But dosn't the voltage meter already measure the resistance with a fixed resistor?

meierfra
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Re: Detector Building C

Postby meierfra » October 27th, 2019, 2:25 pm

The National Event Supervisor for Detector Building will hold a workshop at Haslett High School (MI) on Saturday, Nov. 23 from 10 am - 2:30pm.

In this workshop, he shows you how to build a temperature probe, how to program the TI Nspire, how to calibrate the probe, how to do the circuitry to set up the LEDs, and then a little bit more programming to put it all together. Everyone makes and keeps their own probe and a mini-breadboard with the LEDs on it. (This probe will work with an Arduino, etc. You don't have to have an Nspire.)

This workshop is open to students, coaches, event coaches and anyone interested.

No previous experience with the Nspire is necessary. We provide all the materials. You probably want to bring something to take notes.

​There is a $5 fee for everyone except teachers.
Box lunches are available for pre-order for $5.

To register, visit the webpage https://haslettsciolyinvitational.weebl ... kshop.html

PS I hope it's ok I posted this on the Michigan thread and here.

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Re: Detector Building C

Postby AlterNSO » October 29th, 2019, 9:24 am

My students are using a thermistor with an arduino currently and I didn't let them know that an equation exists that relates resistance of a thermistor to temperature. So to solve the problem of the relationship between voltage and temperature not being easily modeled they came up with equations that modeled it over smaller temperature increments instead of the whole thing. So they currently have an equation for 0-10 degrees C, a second one for 11-20, a third for 21-30 etc. instead of 1 equation for the whole testing interval. My concern is the rules say equation as opposed to equations for the log. I'd rather let them run with what they've come up(it seems to work very well in testing) with as opposed to saying scrap you work and just look up the answer. Anyway I submitted an FAQ but that will be awhile, so just want to check in here to make sure I'm not missing something that would make it obviously ok or not.

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kendreaditya
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Re: Detector Building C

Postby kendreaditya » October 29th, 2019, 9:28 am

My students are using a thermistor with an arduino currently and I didn't let them know that an equation exists that relates resistance of a thermistor to temperature. So to solve the problem of the relationship between voltage and temperature not being easily modeled they came up with equations that modeled it over smaller temperature increments instead of the whole thing. So they currently have an equation for 0-10 degrees C, a second one for 11-20, a third for 21-30 etc. instead of 1 equation for the whole testing interval. My concern is the rules say equation as opposed to equations for the log. I'd rather let them run with what they've come up(it seems to work very well in testing) with as opposed to saying scrap you work and just look up the answer. Anyway I submitted an FAQ but that will be awhile, so just want to check in here to make sure I'm not missing something that would make it obviously ok or not.
This should be fine because most of the limitations in the rules are about the hardware, nothing about software.

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Re: Detector Building C

Postby knightmoves » October 29th, 2019, 2:03 pm

My students are using a thermistor with an arduino currently and I didn't let them know that an equation exists that relates resistance of a thermistor to temperature. So to solve the problem of the relationship between voltage and temperature not being easily modeled they came up with equations that modeled it over smaller temperature increments instead of the whole thing. So they currently have an equation for 0-10 degrees C, a second one for 11-20, a third for 21-30 etc. instead of 1 equation for the whole testing interval.
You can express your piecewise function as a single equation if you like, with the aid of a large pile of Heaviside step functions. It doesn't aid clarity, but ...

marquiza
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Re: Detector Building C

Postby marquiza » October 30th, 2019, 4:21 pm

I realize this is a little late, but I have no idea where to start with building this device. How do you start overall with this event?

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Re: Detector Building C

Postby rayner » November 1st, 2019, 10:14 am

For "provide their own Calibration Thermometer for calibration and testing", what kind of thermometers are people using? Will a typical food thermometer be sufficiently accurate? Also, what kind of calibration can be done at event time? Is there an expectation that our built thermometers will be off by some certain amount? And then calibration means setting some +/- that should be added/subtracted from the computed temperature?

jinhusong
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Re: Detector Building C

Postby jinhusong » November 1st, 2019, 8:57 pm

For regional, you can pre-calibrate your device before the event, because it will use your own thermometer to do the event. The 10 minutes setup, you can safely skip it or just verify one or two points.

For state, The ES will give you a thermometer, you have to calibrate your device with that thermometer in 20 minutes setup time.

Ask you Chem teacher, they should have plenty of lab thermometer with 0.1C resolution.

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Re: Detector Building C

Postby gz839918 » November 2nd, 2019, 11:03 am

I realize this is a little late, but I have no idea where to start with building this device. How do you start overall with this event?
I would advise starting with learning circuits, and especially Ohm's Law. Electronics is the foundation for both the device and the written test, so this is step 1. Once you understand how resistors work, thermistors are only a small step up—they are resistors with constant resistance for a constant temperature, but who change resistance when the temperature changes.

Next you'll want to obtain a microcontroller, circuit pieces, a board, thermistors, and LEDs. If you can't buy them, ask your SciOly team or the physics teachers at your school to borrow some. It seemed like ages had to pass for me to make sense of microcontrollers (I used an Arduino), so I'd recommend using your microcontroller to experiment around with what you learned in step 1. See if you can build circuits where you can calculate the voltage across part of your circuit before actually measuring it, to test whether you've mastered electricity and your microcontroller board. Tutorials for microcontroller code are available online (although honestly a lot of the tutorials aren't all that great).

Finally, you'll want to make one of your thermistors waterproof, but keep the spare thermistors as backups, or for future SciOly students on your team. Then, as with any build event, you want to spend time testing your thermistor over and over in hot water and cold water. You should record the voltage measured for each temperature, being sure that you don't get multiple disparate voltages for a given temperature (that means something's broken). You'll then use these data to formulate an equation that allows you to convert from voltage to temperature. You can now adjust your device as needed to refine its temperature-gauging abilities. Good luck!

Admittedly, my way is the "long way" because each step only becomes clear after you've finished the previous. If anybody has a faster way or other insights, I'd love to hear about them!
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