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Technically speaking, an electrolyte solution is an electrolyte solution, not water, for which you might be "technically" penalized!

So event supervisors are going to be testing for de-ionized water? Conductivity? PH? At what point does water go from water to water with minor contaminants (which happen to be electrolytes) to an electrolyte solution?

If I test a lot of tap waters and find a conductive one, is that OK? Even if probably contaminated with an electrolyte, its just tap water? If so, can't I replicate that tap water?

Just pointing out with continuums it is typically easy to identify the extremes, but the middle ground/transitions are not so easy.

Jeff Anderson
Livonia, MI

As I said above you "might" be penalized. The use of any substance not found in ordinary tap water increases that probability.

This is why you should contact the organizers of the tournament you will be competing in.

Even the lousy water in SW Missouri doesn't conduct electricity well enough to do anything of value. While Joe Fillin Lastminute might be an easy event sup to fool, you won't get far before a judge with enough smarts to catch it shows up.

It's pretty much a moot point anyway. There's really nothing on the list where an ion switch would work better than mechanical.

Just a quick question on something the original poster pointed out. I've seen both photoresistors (LDRs) and photovoltaic stuff referred to as photocells, but they seem to specifically want something that produces a current, not just inhibits flow from a battery or similar. Does this mean I can just wire up a flashlight pointing to a solar panel?

Primate wrote:Just a quick question on something the original poster pointed out. I've seen both photoresistors (LDRs) and photovoltaic stuff referred to as photocells, but they seem to specifically want something that produces a current, not just inhibits flow from a battery or similar. Does this mean I can just wire up a flashlight pointing to a solar panel?

You can definitely have a flashlight pointed at a solar panel to power your next circuit... at least as far as I can tell. I would just like LDR's in unrelated applications, because they can be very useful... and I believe they are cheaper then solar panels, even if they can't drive a current they can still be useful

just my 2 cents, and I still haven't seen any responses on the FAQ's or the Rule clarifications...

-Sean keenan

LDR, in use with a batterys or other power sorce and the loads, act like a dimmers swich, no light sorce to the LDR it opens your circit. When there a littel light to them it lets a small amount go unless the load needs more to operate like a moter that can't rotate with that littel energy. As someone mentions the use of Black Box. I like the idea but it dose takes some fun out of it, but i would think that as long as you can open it and show its workings there should be no problem with it
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Now what when they say you use a moter to create wind energy and it leads to the next action what do they wont with that?

1. Spelling, please. Thank you.
2. Answering your question, it basically means "use a fan to push something".

The hardest thing I can see about using Solar Cells in a device is the limited voltage and current they deliver. The hobby-class solar cells I found produce between 15 and 30 milliamps at between 2 and 6 volts in direct, high-intensity sunlight. The sun is orders of magnitude brighter than a flashlight or LED.

You will have a hard time getting enough energy out of a solar cell in a competition setting to do any appreciable work with it.

Solar cell output voltage remains fairly constant at approximately 0.5 - 0.6 volts. Higher voltages are obtained by connecting several photocells in series. Output current is proportional to the photocell's area and intensity of the light falling on it. (twice the area or light intensity produces twice the current) Since voltage is relatively constant, output power is also proportional to light intensity and area (P=IxE). A solar cell indoors produces only about 5% of its output in bright, direct sunlight. This means you would need 20sq inches indoors for every 1 sq in required outdoors (or a very bright light source).

You may find this article on Performance and Use of photocells informative.