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Unome wrote:

Kyanite wrote:So the FAQS said you cant use salt water for the water task, would pouring the water into a container that has dry salt be against these rules? What do you all think?

That seems to be legal to me. So long as the water being poured is not saltwater, it should be fine. However, you're probably better off doing something more reliable, like this:

davecutting wrote:So could we add water to a container that weighs it and presses a limit switch?

Couldn't the phrase "add water to a closed container so that it completes a circuit..." be seen as only allowing the water itself to close the circuit by using its own conductivity?

andrew lorino wrote:

Unome wrote:

Kyanite wrote:So the FAQS said you cant use salt water for the water task, would pouring the water into a container that has dry salt be against these rules? What do you all think?

That seems to be legal to me. So long as the water being poured is not saltwater, it should be fine. However, you're probably better off doing something more reliable, like this:

davecutting wrote:So could we add water to a container that weighs it and presses a limit switch?

Couldn't the phrase "add water to a closed container so that it completes a circuit..." be seen as only allowing the water itself to close the circuit by using its own conductivity?

Yes BUT the way it is currently written (per coaches clinic) is that a circuit can be completed anyway. Not just through water's conductivity

A little off topic but if a limit switch can be used, does a Lego NXT Touch Sensor fit the bill as well? I'm being a bit lazy for Invites and going the Lego route - does anyone know if a Touch Sensor works the same way (closes a circuit upon actuation)?

My personal take on the task description:
If I press a switch with my finger, my finger is not completing the circuit because my finger is not a conductor in the circuit. I am pressing a switch. The switch is completing the circuit.
If I touch between two high voltage lines, my finger is completing a circuit (to my detriment).

I think the spirit of the problem is clear to use water to "complete"/bridge an incomplete circuit.

Another way to phrase my perspective on the limit switch scenario: Is the water completing a circuit or tipping a (tiny) lever?

That said, the grape vine says that a weight approach is acceptable and I'm of course perfectly happy to follow FAQ answers whenever they appear.

If a limit switch to detect the weight of the water is acceptable, then I don't see any reason I wouldn't accept a wide variety of scenarios incorporating mechanical force. If the NXT touch sensor operates on a make/break basis, I'd lump it in with limit switches. If it uses something like a slide potentiometer to change resistance then it is not completing a circuit (only adjusting the resistance of it). I had RCX instead of NXT, so I don't know the answer off-hand. If the software only allows for on/off feedback from the sensor, I suspect it is probably a make/break device.

Keep in mind that the grape vine also indicates that an NXT microprocessor is an adjustable physical object and so can only be used on one assigned action (no FAQ on the topic as of yet). Which would make it a pretty expensive alternative to a limit switch

The FAQ posted today seems to contradict (and therefore overrule) the guidance given at the coach's clinic. Since "it" in 4.b.iv is being defined as "the water" per the FAQ, the water itself must complete the circuit. This rules out using the weight of the container to trigger a switch.

nicholasmaurer wrote:The FAQ posted today seems to contradict (and therefore overrule) the guidance given at the coach's clinic. Since "it" in 4.b.iv is being defined as "the water" per the FAQ, the water itself must complete the circuit. This rules out using the weight of the container to trigger a switch.

One could argue that the water is the "it" closing the circuit. Just with weight.

SluffAndRuff wrote:A little off topic but if a limit switch can be used, does a Lego NXT Touch Sensor fit the bill as well? I'm being a bit lazy for Invites and going the Lego route - does anyone know if a Touch Sensor works the same way (closes a circuit upon actuation)?

Tell us how the Lego route pans out for you! I originally wanted to do that but my partner and I came to the consensus that it wasn't worth the time investment as we'd have to rebuild later when switching to more capable and compact arduinos.

As far as your actual question (assuming the entire idea of using weight is still valid), it might work, but to be safe I wouldn't. Just use a non-NXT circuit to activate the next action and save the NXTs for when you really need them.

Hey guys
For the water task, are we allowed to include a 9v battery in our design? Other than losing the bonus, is it necessary? I’m doing a saltwater cell, but I am confused as to whether or not we are only allowed to use flow batteries.

Ash123 wrote:Hey guys
For the water task, are we allowed to include a 9v battery in our design? Other than losing the bonus, is it necessary? I’m doing a saltwater cell, but I am confused as to whether or not we are only allowed to use flow batteries.

On a similar note, would adding water to form a voltaic pile count as an added battery and therefore remove the battery bonus?

radioactivated wrote:

Ash123 wrote:Hey guys
For the water task, are we allowed to include a 9v battery in our design? Other than losing the bonus, is it necessary? I’m doing a saltwater cell, but I am confused as to whether or not we are only allowed to use flow batteries.

On a similar note, would adding water to form a voltaic pile count as an added battery and therefore remove the battery bonus?

As long as it is not supplying power then I wouldn't be concerned. Now if you added water in order to form a cell and power a circuit and not simply complete a circuit then that would be an added battery IMO.