barnabas_truman: (young whistler)
A few weeks ago I bought a microphone--something I should have done years ago--and worked out how to record and mix tracks on my computer so I could accompany myself. Here are the recordings I've made so far:

Banish Misfortune, an Irish tune

Chestnut, an English country dance

Fain, another English country dance (under construction)

How Can I Keep From Singing, one of my favorite hymns

Babylon Is Fallen, from Sacred Harp
barnabas_truman: (army)
A while ago I custom-ordered a bunch of Lego parts online. I had been looking for some sort of building toy so I could build frameworks to hold together the demonstration circuits I use in physics workshops, and the Technic pieces with holes for axles seemed like they'd be just the thing for keeping wires in place. Here's the result:



(The stack on the right contains a 9V battery in the upper compartment and a bank of capacitors in the lower compartment. The switch allows toggling between charging and discharging the capacitor bank through a buzzer, demonstrating exponential decay of current.)


On a whim, I decided to get some axles and gears as well. Between workshops and office hours, I occasionally spend some time in my office messing around with these delightful clockwork building blocks, and this is what I've managed to build:







The cream-colored gears have 20 teeth each and the black ones have 12, so each axle rotates at a speed 20/12 times that of the previous one. That means the final axle rotates at (20/12)^6 times the speed of the first (hey! more exponential growth!), or about 21 times as fast. I've ordered a few more gears and axles (I ran out) so I can fill up the rest of the block and get a 60x speed multiplier!

See it in action here:

barnabas_truman: (dwarf)
Just spent a decent chunk of office hours playing with Lego gears... and using them to explain important principles of mechanics to some physics students. I love my job.

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