Introduction: Ufino - Programmable (space) Sound Generator With Arduino
I made this sound generator under request of my wife, who is educator in a kindergarten; after one school year with a number of activities about earth movements, solar system and space exploration, they wanted to talk about the search for extraterrestrial intelligence, in link with the movie “E.T.”.
So we agreed that I would help them in a theatrical performance with children, where they would move some “radiotelescope” antenna along at least one of azimuth and altitude angles and simultaneously a small apparatus would produce some different “space sounds” to simulate reception of signals from the antenna; these space sounds would include the five notes of the theme from the movie “Close encounters of the 3rd kind”.
The generator is substantially a white noise generator, to create some a “background noise”, on which different square wave-based sounds are superposed, the latter being generated by an Arduino and being programmable. A 12 position rotary switch with a diode matrix produces a 4 bit binary word input to Arduino to select one out of 12 different sound sequences (a digital switch could be used instead and the number of sound sequences could be changed at will; my choice was a compromise for easy availability of components and sufficient variety of sound effects for the theatrical performance).
The background noise is generated by a reverse polarised bipolar transistor with some amplification (first two transistors BC547 in the schematics), which is controlled in 4 steps by Arduino (and signalled by the yellow LEDs in the schematics, which also play an aesthetic role), and a mixing with the Arduino-generated square wave sounds; the circuit then comprises also a power supply from the mains.
The Arduino software is based on a loop where the status of the rotary switch and of a single on/Off control switch is checked and a portion of one of 12 different square wave-based sound sequences is produced accordingly. By simply reprogramming Arduino changes may be easily implemented and also a completely different set of sounds may also be generated. The produced signal is delivered as output to an outlet where an external amplified computer speaker set may be plugged in with the input stereo jack.
The whole set is mounted in a box made of laser-cut MDF panels connected by slats and screws at the corners.
List of electrical components:
For white noise generator and mixer:
1x 100 μF 20V electrolytic capacitor
2x 10 μF 20V electrolytic capacitor
1x 0.1 μF 20V capacitor (non-electrolytic)
2x 1.5 k resistor
1x 3.9 k resistor
1x 4.7 k resistor
1x 180 k resistor
2x 330 k resistor
1x 680 k resistor
1x 100 k trimmer
4x BC 547 (or similar) NPN transistor
2x yellow LED
1x stereo jack socket
For programmable sound generator:
1x Arduino Nano (or other Arduino)
1x 12 positions 1 line rotary switch
1x lever switch (or similar)
20x 1N4148 (or similar) diode
5x 15 k resistors
For power supply:
1x Transformer 220 V – 2x 12 V 0.35 A
2x 1N4007 (or similar) rectifier diode
1x 2200 μF 50V electrolytic capacitor
1x 47 μF 20V electrolytic capacitor
1x 0.47 μF 50V capacitor (non-electrolytic)
1x 0.1 μF 20V capacitor (non-electrolytic)
1x 5.6 k resistor
1x lever switch (or similar) 220 V
1x Red LED
1x Input power cable with plug
Arduino software:
The Arduino sketch is the file sketch_may30_v10.ino ; the pitch definition file pitches.h should also be in the same directory when uploading the sketch.
