Photocell Bonus

[fleet130]

A lot of teams don't even know about the clarifications on Soinc.org.

It never ceases to amaze me, how much people don't know. Every team gets a rule book and it's in the book. At lease event supervisors have the excuse that they don't get a copy of the rule book. I have been to tournaments where event supervisors had never been given a copy of the rules, just a verbal explanation of the event.

Are tournaments really required to honor the national clarifications? Only to the extent that they know about them and choose to follow them. What recourse does a team have if they choose not to follow them? Tournaments have been modifying the rules because they disagree with them since the beginning of Science Olympiad!

[Flavorflav]

A lot of teams don't even know about the clarifications on Soinc.org.

It never ceases to amaze me, how much people don't know. Every team gets a rule book and it's in the book. At lease event supervisors have the excuse that they don't get a copy of the rule book. I have been to tournaments where event supervisors had never been given a copy of the rules, just a verbal explanation of the event.

Are tournaments really required to honor the national clarifications? Only to the extent that they know about them and choose to follow them. What recourse does a team have if they choose not to follow them? Tournaments have been modifying the rules because they disagree with them since the beginning of Science Olympiad!

I have no problem penalizing people who violate a clarification on soinc or a state or regional site if it would give them an unfair advantage over teams that followed the rules. In this case, though, not knowing about the clarification would be its own penalty, since I think everybody agrees that the photocell task is a lot easier than the solar cell task. It seems to me that 2nd tiering somebody for following the printed rules when there was no ambiguity is a bit harsh.

In NY, soinc clarifications and FAQs are binding, as long as they are posted two weeks before the competition - theoretically, at least. A lot of supervisors aren't as up on them as they should be.

[yoyo1299]

Hey guys,

thanks everyone! I actually managed to get it work, I used a very bright lamp. Now I just need to find a bulb that will be bright enough. I am using 4 AA batteries, and that seemed to work.

[old]

OK maybe I am confused but I don't see anything about a bonus for using a photocell in Mission Possible. I do see one of the tasks involves the use of a photocell but I see no bonus points awarded for it in the scoring section of the rules. Am I missing something or is this thread simply about the photocell task?

[Sir_L_Jenkins]

You get points for it, you get 25 points (I think off the top of me head) for any of the tasks, A-J. However, if you're looking on the second page of the rules where it has an example TSL, that's just an example of a possible sequence, and it does omit a few steps, which may be the photocell. But don't pay any attention to the that as official scoring guidelines as its just an example. Besides, the photoresistor is used to allow power to something else, so one step won't include simply just shine light on a photoresistor.

[pjsetnicker]

Just to help everyone. I recently discovered this discussion. It helped my team alot.

What I did was take the solar cells and attach three of them to a C-battery pack (2 batteries)... along with a standard motor you would find in a remote controlled car persay. We shined the light used in a Eveready Heavy Duty flashlight (powered by one of those square lantern batteries) - worked like a charm.... until I burnt the light bulb out ... hahaha

[Balsa Man]

Re: photoresistor reliability and failure modes

Anybody have any experience/info/insights on the reliability of photoresistors, and factors that affect the reliability?

We're not using the Radio Shack ones- got some from our local electronics supply place. Using a single one- 9.6v power, tripping a relay/powering a fan motor. Light source is a 12v/20w landscaping bulb; photoresistor mounted about a quarter inch away. Light-on for ....a second or less is part of set-up testing process.

Pre-Regionals testing and calibration put the unit through....25-30 duty cycles. It was working fine Friday night, and on a check Saturday morning. Then when the guys were doing setup to run at Regionals, the circuit test for fan failed. They correctly figured out they'd had a photoresistor failure, and scrambled to cut it out and do an alligator clip replacement. Replacement worked.

The problem was, their setup time was down to 3 min, hurried through, missed a check on flag raising mechanism, which led to one touch - and 4th, while our other team's box (same component set and sequence) ran flawlessly, and hit 60.04 sec....

Plan is to put a fresh (but tested a couple of times) photoresistor in (on both boxes) for State, which should prevent the problem, but just wondering how much of the problem is the nature of photoresistors, and how much might be from heating from the lamp
?


Problem was

[Flavorflav]

Uncle Fester posted this a while back:

I had two devices have working photocells at this past weekend's invitational. One was from my team, done the night before with one working test beforehand.

ELECTRONICS GOLDMINE sells a pack of tiny 3v cellphone vibrating motors for (I think) $2.50. We also got a dozen of the 75 cent photocells on sale. While we were at it, we got an assortment of gearhead motors; real powerful and nice and slow.

Photocells had a bright resistance of 24 ohms. This was low enough to be a problem! So, each photocell was wired in series with a 24 ohm resistor to bring the bright resistance UP to 50 ohms. This effectively increased the number of photocells needed to four, but it eliminated overheated photocells, which causes aggravating intermittent problems.

Hooked up to 9v (D cells-- we don't use those rectangular niners), there was plenty of voltage and power available to run the 3v cell pager motor, which hopped around on a precarious spot, fell about 50cm, reached the end of its wire, and tripped a really touchy snap switch.

We haven't run into a problem yet, but honestly we haven't really finished building yet. It ran at regionals half-built.

[Balsa Man]

Thanks.
That does suggest heating could be the source of the problem - from a solid source.
Thanks.
I find myself often telling others to "read the previous posts" before asking a question...
Mea culpa...