The maker movement is making science exciting again. Forget the lame baking soda “volcanoes” and the zillion-dollar supercolliders — just as punk rock took music back from the supergroups and big studios, “punk scientists” are making inexpensive new tools to conduct real experiments in garages, schools, and hackerspaces. In MAKE Volume 31, you’ll learn how to make DIY laboratory equipment (even a scanning electron microscope!), create high-voltage sparks from falling water, control a cockroach electronically, get started in biotech, and see how individuals and schools are networking their data for real scientific discoveries. Plus: Get started with multicopters or servo controllers, and build an automatic dog ball launcher, great-sounding speakers with flashing LEDs, a classic folding-wing Rocket Glider (a new MAKE kit), an iPad music desk, a levitating solar Mendocino Motor, and much more.
Lord Kelvin’s Thunderstorm
Video of the thunderstorm in action
By Chris Connors
- 3D part files for base connectors, bearing plate connectors, stator connectors, rotor block, and front and rear rotor bushings
- Laser cutter files for bearing plate, 2 designs
By Dean Segovis
Video overview of the Fetch-O-Matic
Videos of the Rocket Glider in action
Project Code and Templates
Video demo of the speakers
Monkeysailor’s Photo Lab
By Andrew Lewis
Project Code, Schematics, and Templates
Panel artwork by John Ranford
iPad Music Desk
By Reed Ghazala
Schematics and cutting templates
Endless staircase of sound. (45 minutes)
When you play this sound in a loop, it sounds like it’s constantly rising in frequency, or falling, if you reverse it. But since it’s just looping, it actually goes nowhere. Its discoverer, Roger Shepard, first described it in 1964 as the audio equivalent of the endless staircase illusion, but Béla Julesz and Ira Hirsh argued later that a better analogy is a rotating barber pole.
Our version of a Shepard scale will be a sequence of 6 complex tones that follow an ascending scale, a whole-note scale (in our case: A, B, C#, D#, F, G) that divides the octave into 6 equal intervals. Each complex tone will consist of its single note playing at multiple octaves, but we’ll make the volumes highest in the frequency range where we hear best, and taper them off at the extremes.
When we loop the sound, our brain will hear the intervals rising from tone to tone in its midrange, but be less aware that at the extremes, new very low notes sometimes emerge at the bottom and very high ones drop off at the top.
To create this scale in Audacity, generate, overlay, and sequence a series of 6 complex tones, each composed of the frequencies listed down successive columns of the table in Figure P and with a duration of 0.5 seconds apiece. It’s a good idea to save your work along the way by saving out a separate track for each column, naming it after its musical note. Then, once you have the 6 tracks saved, open a new file in Audacity and copy each track into it. When pasting one track onto the end of another, don’t forget to move the cursor to the end of the first track using the Skip to End button.
After you’ve pasted all the tones in, Loop Play to hear the unending rise in pitch. Highlight the track and use the Effect → Reverse to hear it as an unending fall.
Electronics: Fun and Fundamental, The Ching Thing
The schematic in Figure C (page 159) should have no break in the line from the Output to the One-shot timer. Here’s the correct version:
We updated the schematic in Figure E (page 161) to reflect the added simple power switch and reset switch that discharges the large capacitor. Here it is:
Toy Inventor’s Notebook: Breadboard Bots
By Bob Knetzger