Day 58: Potential Energy

(Author’s note: I’ve got some catching up to do. I hit two days which were so crazy-full that there was no time to write. Here goes.)

Right before the MechaniCrawl, my muse had just gotten back from a cross-country flight, so we’re ready for a day of rest and quiet relaxation. She’s finishing another knitting project. This one’s for her sister, but it looks really good on her as well.

So it was a quiet day at home. Remember the rule? Any time there’s a quiet day without many pictures, I unwrap another Secret Plan.

Secret Plan 118: Pressure Reducing Micro-Generator

Most houses have devices called pressure-reducing valves. They’re important for many reasons, and building codes require them on the interface from the water main. Additional pressure reduction is sometimes used to save water in the garden or shower.

…so the water that comes to your house is higher pressure than you need. Call it 100 psi (pounds per square inch). And let’s say you only need it to be 30 psi in your sink, shower, and garden hose.

What if we could use this pressure difference to generate electricity? First step is to find out how much energy we could get from it.

This pressure difference is effectively the same as two water tanks at different heights. If these two tanks physically existed, you can imagine that by water moving from one tank the other, you might generate some power.

This isn’t the device, just an illustration of where the energy would come from.

In this example, a typical family using 120 gallons of water in a day would get 60 watt-hours for free each day, or about enough to run a laptop computer for two or three hours.

That’s not huge, but free energy is pretty popular these days.

Random Assertion: Micro-generation ideas usually aren’t cost effective at first, but they also don’t cost much.

Steganographic data: 1862/1.4

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Day 44: Robot Mayhem

Time for a cool surprise: I’m letting one of the Secret Plans out.

Today was pretty low-key (projects at home, and some time spent with our smart fun neighbors, discussing things which must remain secret).

So new rule: Any time I have a low-key day with no photos or dangerous activities, I’ll shed light on one of the items in the Secret Plans list.

Secret Plan #31: Wacky Robot Races

What if you could teach robotics concepts to a second-grade class? It turns out you can. In 1997 and 1998, I was the “robot guy” at the El Granada Elementary School science day. Afterward, I set up this website as a contact point for anyone who had follow-up questions.

Having no kids doesn’t get you out of science fair duty, unless you also have no neighbors.

The first year, I modified Buggo, a robot I had already built. I set him up with a system where 16 kids can drive at once, democratically.

I also brought Max, and old Hero 1 robot, and disassembled him for the class, showing all of his parts and talking about what they’re for.

Lessons learned year 1:

• • Having kids shout out “Left! Right!” is less effective if they’re not all clear on which is which.
  • Robots can malfunction, but kids can too.
  • Keep the activities simple. Sixteen kids driving one robot are not sixteen times as efficient as one kid driving a robot.
  • Have a spare robot handy.
  • Rechargeable batteries are great for normal robot use, but use alkalines for special events like this. They last longer, and you can replace them easily.
  • If there is any way to make it operate without a tether, it’s a really good idea.
  • Teachers have the hardest jobs in the world.

The second year, I built three brand new robots, Pluggo, Cricket 1 and Cricket 2. These were all “light seekers”; shine a flashlight at them, and they’ll rush toward you (or away from you, depending on the setting).

Lessons learned year 2:

• • Kids really love flashlights. Don’t pass them out until you’re ready to start.
  • Talk first, then play. The two cannot be done in reverse order.
  • Teachers really do have the hardest jobs in the world.

Where are they now?

• The kids: It’s eleven years later, so I guess all of those little kids are over 18. Yikes! Hopefully their memories of the Wacky Robot Races are as fond as mine.
• The robots: Cricket 1 and Cricket 2 are dusty, but in good shape. They might even work. Buggo and Pluggo have long since had most of their important parts borrowed for other projects. Max needs a tune-up.

Here’s what they all look like today:

Buggo’s original brain is missing. I can’t remember which project it ended up in. It’s here somewhere.

Pluggo had the same brain as the Crickets, but with a bigger platform. Now it’s essentially just a mobile platform with proximity sensors.

Cricket 1 and Cricket 2 probably still work. They were built in about a week, and their “brain” is really no more than a set of hardwired reflexes, based on a circuit board I etched in the bathroom sink at home.

Max is special. He needs a serious tune-up. His arm is in a box, and the last time he was actually powered up was to say something charming to my muse, when we were first dating.

Tip: Getting a home-built robot to tell her she’s beautiful works better then you’d think.

Random assertion: If you ever give 30 kids 30 flashlights, expect to lose control of the situation immediately.

Steganographic data: 1880/0.4