Mission Possible C

[twototwenty]

[insert "not place for official clarifications" spiel here]

Just want some opinions:
Based on what appears to be the generally accepted interpretation that mechanically flipping a switch is mech -> elec, would thermally connecting a circuit be, in your opinions, heat -> elec?

[Phys1cs]

Based on what appears to be the generally accepted interpretation that mechanically flipping a switch is mech -> elec, would thermally connecting a circuit be, in your opinions, heat -> elec?

are you completing or connecting?

I would think if you were to complete a circuit with thermal energy, then it would be thermal-->elec, but if you're connecting two circuits..? what do you mean exactly by thaT?

[gorf250]

I also would not count a commercial battery as Chem -> Elec not because it is not student made, but because prior to the start of the event the battery already had a voltage difference between the poles which represents a preexisting electrical potential. To count as Chem -> Elec in my book one would need to assemble the battery during the run, so a new electrical potential is created. .

I appreciate you not discounting commercial batteries due to the fact that they are premade, because if nothing premade is allowed to be counted as a transfer, that would make motors, matches, candles, rocket igniters, etc. illegal as well, which is somewhat absurd.
However, I disagree with the idea that batteries should not count for transfers due to the pre-existing electric potential. The fact remains that in order for the electricity to flow in a circuit in a device, a chemical reaction must occur in the battery. In order for the pre-existing electric potential to be sustained, the chemical reaction must continue to occur in the battery. The electrical energy generated most definitely began as chemical potential energy when the device started the run. In addition the rules explicitly state that a battery can receive points. The main question in my mind is whether a battery is counted as chem to elec or as chem to whatever it powers, ie. a battery powering a motor could be chem to mech.

[Flavorflav]

I do not think many event supervisors will agree with your reasoning about the batteries - they have not been scored in previous years, to the best of my knowledge. Also, as I've said before, if you try to count a battery as chem -> electrical, you are opening yourself up to a charge of parallel paths since the reaction clearly began before you threw your switch.

[jroorda]

Batteries are certainly a finicky issue. The chemical reaction begins as soon as the materials come in contact with each other, but the reaction is paused when the electrical potential of the materials counteracts the cell's potential and equilibrium is reached. When the circuit is made it gives the electrons somewhere to go and the oxidation-reduction reaction can continue. To faithfully represent this I think you would need to go from Mech->Elec->Chem->Elec, but I don't think any judge would let you get away with that however correct it may be. You also have to remember that at most competitions even including regionals and states the event supervisor likely has only read through the rules a few times and has not had to struggle with wording like we have, so they are liable to interpret things in their own way.

The rule that states that all transfers must be visible could also be an issue, as I can't claim to see the reaction inside a sealed battery and unsealing the battery is against the rules. We all know that batteries use chemical reactions, but the rules state that if it is not visible it does not count. The other rule that states that batteries can count depending on how they are used is something, but I wouldn't count on it justifying your transfer without further clarification. The wording is vague enough that the judge could say that it applies to using the battery as a mass in mechanical transfers or in some other way.

[olympiaddict]

All interesting arguments, it's tricky with all these complicated concerns. And I agree, I think it's clear that these questions are being frequently asked, and the only way we can reliably resolve this will be with official clarifications.

I'm wondering about the whole "visible" rule though. For example, thermal -> anything isn't really visible. Like, you see the light, movement, etc that is produced by the transfer, but it's not like you can actually see it being converted/ triggered so I don't think that would rule out a battery. I think it might mean more that you can't have it locked away inaccessible in the device, but I'm unsure.

Also, do you guys think it would be illegal to use a MOSFET, photoresistor, and resistor to make a homemade phototransistor? Because I'd hesitate to risk it, but those components would be allowed if they were part of a commercial phototransistor unit.

[Flavorflav]

All interesting arguments, it's tricky with all these complicated concerns. And I agree, I think it's clear that these questions are being frequently asked, and the only way we can reliably resolve this will be with official clarifications.

I'm wondering about the whole "visible" rule though. For example, thermal -> anything isn't really visible. Like, you see the light, movement, etc that is produced by the transfer, but it's not like you can actually see it being converted/ triggered so I don't think that would rule out a battery. I think it might mean more that you can't have it locked away inaccessible in the device, but I'm unsure.

Also, do you guys think it would be illegal to use a MOSFET, photoresistor, and resistor to make a homemade phototransistor? Because I'd hesitate to risk it, but those components would be allowed if they were part of a commercial phototransistor unit.

That seems like a very bad risk to me. It would probably cost more to make than to buy, might not work as well, and carries a very high risk of construction violation.

[olympiaddict]

I agree it's risky, that's why I'd probably not do it, but I was wondering what you guys thought.
I do think it would be quite possible to build your own setup that would work as well or better than the commercial options I've seen. I'm just having trouble finding any phototransistors that will switch a decent amount of current, since most are not designed to switch heavy loads directly but instead are meant to be signals interfaced with digital circuitry.

[FawnOnyx]

I agree it's risky, that's why I'd probably not do it, but I was wondering what you guys thought.
I do think it would be quite possible to build your own setup that would work as well or better than the commercial options I've seen. I'm just having trouble finding any phototransistors that will switch a decent amount of current, since most are not designed to switch heavy loads directly but instead are meant to be signals interfaced with digital circuitry.

Hmm you'd have to try and see but I think phototransistors in parallel could solve that problem (shares the current load). I also vaguely remember reading somewhere that if you exposed the base of a transistor by opening the casing, it essentially operates as a phototransistor but still works as the original transistor. That would definitely need some looking into though.

[Chemchic]

Have I missed where or if the ETL was posted? I went to soinc.org and still don't find it but might be looking in the wrong place??