My strategy with my emerging Demo Guy automata was to replace the hand crank with a continuous servo.
But when I pitched the idea to Jack Greenfield, over lunch at a Shwarma place near the Northeastern campus, he had a better idea.
"Why not just use a DC motor?" he asked. "It's simpler -- it will just spin, and then stop. You'd use a continuous servo only if you wanted it to stop at a precise spot. You don't need that."
Whoa, that is simpler. I wish I knew that back when I was using a continuous servo to spin that paper chocolate grinding stone back at the Taza Chocolate Bar.
But, onwards... to DC motors.
Jack deliberated maybe 30 seconds before recommending this one. Clearly, brand meant nothing.
I liked the look of it -- pure commodity, direct from China: $5.99. Rated 10,000 rpm.
It looks like what you'd see inside something plastic and mechanical and cheap -- if you dropped it.
The one-sentence description on the web page reinforced that idea.
"Used for electronic game machine, electronic toys, car toys, electronic equipments, etc."
The vendor I ordered from, Uxcell, claims to be the "Best Distributor of Chinese Wholesale Electronics."
In the upper left corner, where the logo usually goes, was a broken graphic icon. My browser said, "Not Secure."
But what the hell, I'd take a chance on Uxcell. I liked their attitude.
"Crazy products are being made all the time," Uxcell assured me. "Things you can't imagine."
I ordered two.
And I ordered one of these, which looks nearly identical on the outside, close to the same price, but rated slightly slower: 6000 rpm.
And, what the hell, one more: much smaller, a little more expensive ($12.70), lower RPM (1000), but higher torque.
Smaller, slower, but higher torque.