Sound / Physical computing
Elevator
Music Box
An ordinary elevator ride becomes an orchestral experience. A self-contained box senses movement and altitude to determine the musical course.
01The project
The Elevator Music Box is designed to sit inside an elevator and play dramatic sound compositions in response to its direction and altitude. It works independently, without any mechanical connection to the elevator or its control systems.
A barometric pressure sensor lets a microprocessor determine where the elevator is and how it is moving. The processor sends pulses to a modified MP3 player, selecting music that rises, falls, and resolves with the ride—a playful experience for unsuspecting passengers.
- First Location
- 55 W 13th Street
New York City - Elevator range
- Basement to floor 9
South elevators - Created at
- Parsons
Design and Technology
02Sound design
The music is the heart of the project. The orchestral elements feature timpani, snares, and large horn sections building upward in melody, speed, and intensity as the elevator rises; the other falls from top to bottom through a sound design of apocalyptic machinery.
The reference elevator ride between floors 1 and 9 takes 26 seconds with no stops.
The score is designed in sections. When the elevator stops, the processor can find a musical breaking point within roughly two seconds, or a measure or two, then switch to a short “ta-dah” resolution. If the elevator continues, a new section begins at the musical level corresponding to that floor.
Only passengers riding all the way up and back down experience the complete piece. An alternative score utilizes whispering voices that grow in number and volume.
How the musical sections fit together
03Technical
construction
The box uses changes in air pressure to detect movement, direction, and position. Those readings pass through an analog-to-digital converter to a Basic Stamp microprocessor. Relays then operate the MP3 player’s buttons, and an amplifier drives the speakers.
Parts list
| Component | Brand | Qty. | Part / specification | Reference |
|---|---|---|---|---|
| microprocessor | Parallax Basic Stamp | 1 | BS2SX | Archived reference |
| single op amp | Dallas Semiconductor / Maxim | 1 | MAX 407 | Archived reference |
| 5V 12bit serial ADC | Dallas Semiconductor / Maxim | 1 | MAX187 | Archived reference |
| barometric pressure sensor | Motorola | 1 | MPX4115A CASE 867-08 | Archived reference |
| LCD screen | Scott Edwards Electronics | 1 | BPI-216 Serial LCD | Archived reference |
| 13.2V 18W BTL audio power amp | Hitachi | 1 | HA 13118 | Archived reference |
| 5V voltage regulator | ST Microelectronics | 1 | 7805 | Archived reference |
| 1M ohms 3/4 watt trimmer | Trimpot | 2 | 300 GP [105/0202M] | — |
| 1M ohms 1/2 watt trimmer | — | 1 | 104 | — |
| dry reed analog relay | Tyco Electronics | 4 | OEG OMR 4 / 250 ohms | Archived reference |
| mp3 player | Diamond RIO | 1 | Rio Classic 300 32MB | Archived reference |
| capacitor | — | 2 | 4.7uF | — |
| capacitor | — | 3 | 0.1uF | — |
| resistor | — | 1 | 133k ohms | — |
| resistor | — | 1 | 100k ohms | — |
| resistor | — | 2 | 54.6k ohms | — |
| resistor | — | 2 | 65 ohms | — |
Circuit diagram and main board
Modifying the MP3 player
Most digital music devices use momentary switches for power, play, forward, reverse, stop, and settings. A relay can briefly connect a switch’s terminals, doing the work of a finger pressing a button.
Each switch on the Rio 300 MP3 player is connected to its own relay by two wires: play (which also turns the player on), forward a track, reverse a track, and stop. Soldering into these small switches is one of the most delicate parts of the build; a small slip can ruin the player.
Calibration, LCD, amplification, and batteries
Calibrating the altimeter
Out of the box, the altimeter does not register enough change to be useful inside the elevator. With Marko Tandefelt’s technical guidance, calibration involved many hours of riding up and down and adjusting two 1 MΩ trimmers for the ADC reference and low-end op-amp settings. Once calibrated, the sensor can detect a change of about one foot.
The first op-amp circuit uses a trimmer to shift the small varying voltage—around 2.5–2.6 V—down toward zero. Across nine floors, the resulting change is only about 0.05 V. A second amplifier stage, with its gain set by another trimmer, expands that range enough to detect changes at roughly one-foot intervals.
The LCD screen
The LCD is crucial during calibration: it shows the voltage rising and falling as the elevator moves. The readings at each floor establish the ranges used in the code. Each elevator needs its own calibration, and its speed also affects the musical timing.
Audio output
The Rio’s output needs amplification to reproduce the music at a useful volume. A 13.2 V, 18 W amplifier drives two 4 Ω Bose speakers manufactured by Apple Computers. A stereo ⅛-inch mini plug connects the MP3 player to a soldered breadboard connection on the amplifier kit, with low-resistance Monster speaker wire running to the speakers.
The photograph labels the amplifier “10 watt”; the parts list specifies 18 W.
Battery power
The Basic Stamp has its own rechargeable 9 V nickel-metal hydride battery. The MP3 player uses a separate 1.5 V AA nickel-metal hydride battery, and the amplifier uses a 7.2 V / 2000 mAh nickel-cadmium battery pack. Battery life remains a limitation: even the compact, high-end batteries last only a couple of hours at full operation.
04Code
The program created for the Parallax Basic Stamp BS2SX reads the pressure sensor, compares successive readings, maps ADC values to floors, and sends pulses to the MP3 player.
View the Basic Stamp program
'{$STAMP BS2sx}
SCLK con 5
CS con 6
SerData_in con 7
N9600 con $40F0
I con 254
CLR con 1
LINE2 con 192
L1_C7 con 135
adc var word
floor var word
x var byte
c var word
pressure1 var word
pressure2 var word
direction var nib
pause 1000
serout 8, N9600, [I, CLR]
direction = 0
main:
gosub check
gosub compare
goto main
check: 'check, convert and print
low CS
Shiftin Serdata_in,SCLK,MSBPOST,[adc\12]
high CS
pressure1=adc
pause 250
low CS
Shiftin Serdata_in,SCLK,MSBPOST,[adc\12]
high CS
pressure2=adc
debug dec direction
if adc>=2400 then floor1
if adc>2350 and adc<2400 then floor2
if adc>2050 and adc<2350 then floor3
if adc>1900 and adc<2050 then floor4
if adc>1750 and adc<1900 then floor5
if adc>1600 and adc<1700 then floor6
if adc>1500 and adc<1600 then floor7
if adc>1300 and adc<1450 then floor8
if adc<1300 then floor9
print:
pause 1 'print to lcd
serout 8, N9600, [I, LINE2, floor]
pause 1
serout 8, N9600, [I, CLR]
pause 1
serout 8, N9600, ["volts: ",dec adc]
pause 1
serout 8, N9600, [I, LINE2,"floor: ", dec floor]
pause 1
return
compare:
if pressure1>pressure2+5 then main
if pressure1<pressure2-5 then main
c=pressure1
gosub check
if pressure1>pressure2+5 then main
if pressure1<pressure2-5 then main
c=pressure1
gosub check
if pressure1>pressure2+5 then main
if pressure1<pressure2-5 then main
goto upcd
stopcd:
if direction = 0 then main
high 4 'send pulse to pin 4 which is STOP on MP3 player
pause 200
low 4
direction = 0
return
upcd:
high 1 'send pulse to pin 1 which is PLAY on MP3 player
pause 200
low 1
return
downcd:
if direction = 2 then main
direction = 2
high 2 'send pulse to pin 2 which is FW button on MP3 player
pause 200
low 3
high 1 'send pulse to pin 1 which is PLAY on MP3 player
pause 200
low 1
return
floor0:
floor=0
goto print
floor1:
floor=1
goto print
floor2:
floor=2
goto print
floor3:
floor=3
goto print
floor4:
floor=4
goto print
floor5:
floor=5
goto print
floor6:
floor=6
goto print
floor7:
floor=7
goto print
floor8:
floor=8
goto print
floor9:
floor=9
goto print
05Physical design
Letting the inside become the outside
The enclosure uses a triangular profile to fit into an elevator’s corner without protruding far from the walls. A transparent enclosure invites passengers to inspect the circuitry, making the functional arrangement of the components part of the visual design.
An additional circuit board randomly illuminates an array of blue lights, giving the box a little life of its own.
A more discreet enclosure
An alternative design proposes a smaller, less visible enclosure to address the constraints of installation in an elevator. The proposed housing is small, fire-resistant, and out of the way.
The proposed solution is to place the device inside a corner mirror, possibly using a transparent material approved for elevator use, mounted at the top corner of the cabin.
06Credits
- Drew Baron
- Concept, music, code, circuitry
- Nicole DiDio
- Material Design
- Jatom Joon
- Material Design
- Marko Tandefelt & John Sharp
- Technical direction