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'Sound Kit' electronics kit

'Sound Kit' is an electronics kit aimed at young people. Correctly soldering the components onto the included printed circuit board (PCB) creates a badge that visualizes the volume and frequency (the pitch) of sound via the microphone. As a bonus, the badge also creates a light scanner like used for example used by Kitt in the Knight Rider series.

Er is ook een pagina in het Nederlands aanwezig.

Sound Kit front back

The front and back of a ready built Sound Kit.

Contact

You can send your questions about the Sound Kit project to ivo [atsign] digiterraan.nl.

The engineers

Ronald PA5RB, Ivo PA1IVO and Leo PA0LEZ.

Thanks to

AMOLF for allowing us to develop the prototype.
Emco Electronics for the technical assistance.
MegiQ and the VERON-Fonds for sponsoring kits for both the Ham Radio Convention 2018 and the VERON Pinksterkamp 2019.
Henk-Jan Boluijt for taking a number of pictures.
Bas Rodriguez for proof-reading the descriptions.

Building instructions

The building instructions can be found in a colour PDF file. When printing the manual, use a colour printer in order to see the red lines in the pictures. The instructions are only available in Dutch, but the instructions will be useful for everyone due to the graphical presentation.

Manual

In the manual you can find all the information you need to know to operate the Sound Kit, however in Dutch only. It is a PDF file in A4-format, containing two A5 columns of text. By double-side printing the A4 and cutting it exactly into two equal parts, you get two manuals in A5 format.

Spectrum mode testing

By playing the special .wav file, the spectrum mode of your Sound Kit can be tested. Hold your Sound Kit close to the speaker: the .wav file plays first eight tones that will light the leds one-by-one and second four dual tones that light two leds simultaneously.

The .wavfile plays the following tones:

500 - 750 - 1000 - 1250 - 1500 - 1750 - 2000 - 2250 - 500+1500 - 750+1750 - 1000+2000 - 1250+2250 Hz.

Schematic

Schematic of the Sound Kit electrical circuit.

SW1: Spectrum mode
SW2: Volume mode
SW3: On/Off
SW4: Disco mode
TP1: See Auto calibration below

Electronic parts

Part & reference Name / value Manufacturer part number Supplier & order code

Resistors R1,R4,R17 2.7 kΩ 1% VISHAY MRS25000C2701FCT00 Farnell 9466827

Resistors R2,R3,R5 33 kΩ 1% VISHAY MRS25000C3302FCT00 Farnell 9467351

Resistors R6,R7 15 kΩ 1% VISHAY MRS25000C1502FCT00 Farnell 9464689

Resistors R8 ... R16 1 kΩ 1% VISHAY MRS25000C1001FCT00 Farnell 9465170

Capacitor C1 1.5 nF (pitch 2.54 mm) KEMET C320C152J1G5TA Mouser 80-C320C152J1G

Capacitors C2,C4,C5 4.7 µF (6.3 x 11 mm) RS Pro 711-1784 RS 711-1784

Capacitors C3,C6,C7,C8 10 nF (pitch 5.08 mm) AVX SR211C103KAR Farnell 1100407

Leds D1 ... D8 5 mm red 120° - LEDs-buy 08-05-02-RO

Switches SW1 ... SW4 Tactile Switch off-(on) ALPS SKHHARA010 Mouser 688-SKHHAR

Microphone MK1
(alternative:) Electret
(Electret) EKULIT EMY-9765P
(MCKPCM-97H45P-40DB-4808) Reichelt MCE 100
(Farnell 2396073)

IC socket U1 28 pins (2 x 14) 7.62mm spacing ASSMANN WSW AR 28 HZL/7-TT RS 674-2498

IC socket U2 8 pins (2 x 4) 7.62mm spacing ASSMANN WSW AR 08 HZL-TT RS 674-2479

Microcontroller U1 ATmega88V-10PU Atmel ATmega88V-10PU Mouser 556-ATMEGA88V10PU

Op Amp U2 Low-Power Op Amp Microchip MCP6002-I/P Farnell 1292245

BT1 Battery holder 2 x AAA Keystone Electronics 2468 Mouser 534-2468

Batteries 2 x 1,5 Volt AAA - -

Part & reference	Name / value	Manufacturer part number	Supplier & order code
Resistors R1,R4,R17	2.7 kΩ 1%	VISHAY MRS25000C2701FCT00	Farnell 9466827
Resistors R2,R3,R5	33 kΩ 1%	VISHAY MRS25000C3302FCT00	Farnell 9467351
Resistors R6,R7	15 kΩ 1%	VISHAY MRS25000C1502FCT00	Farnell 9464689
Resistors R8 ... R16	1 kΩ 1%	VISHAY MRS25000C1001FCT00	Farnell 9465170
Capacitor C1	1.5 nF (pitch 2.54 mm)	KEMET C320C152J1G5TA	Mouser 80-C320C152J1G
Capacitors C2,C4,C5	4.7 µF (6.3 x 11 mm)	RS Pro 711-1784	RS 711-1784
Capacitors C3,C6,C7,C8	10 nF (pitch 5.08 mm)	AVX SR211C103KAR	Farnell 1100407
Leds D1 ... D8	5 mm red 120°	-	LEDs-buy 08-05-02-RO
Switches SW1 ... SW4	Tactile Switch off-(on)	ALPS SKHHARA010	Mouser 688-SKHHAR
Microphone MK1 (alternative:)	Electret (Electret)	EKULIT EMY-9765P (MCKPCM-97H45P-40DB-4808)	Reichelt MCE 100 (Farnell 2396073)
IC socket U1	28 pins (2 x 14) 7.62mm spacing	ASSMANN WSW AR 28 HZL/7-TT	RS 674-2498
IC socket U2	8 pins (2 x 4) 7.62mm spacing	ASSMANN WSW AR 08 HZL-TT	RS 674-2479
Microcontroller U1	ATmega88V-10PU	Atmel ATmega88V-10PU	Mouser 556-ATMEGA88V10PU
Op Amp U2	Low-Power Op Amp	Microchip MCP6002-I/P	Farnell 1292245
BT1	Battery holder 2 x AAA	Keystone Electronics 2468	Mouser 534-2468
Batteries	2 x 1,5 Volt AAA	-	-

Electronic parts Sound Kit.

PCB layout

The PCB layout is available as:

A set of Gerber files (zip file).
A set of images (one PNG file).

The PCBs are manufactured at Safe-PCB.

Firmware

The microcontroller (ATmega88, device signature 0x1E930A) firmware is available as .hex file. The fuse bits settings are: 0xF9, 0xD6, 0xE2 (extended, high, low).

Auto calibration

The microcontroller uses the internal RC oscillator as clock base, which is factory calibrated. To check and possibly improve the factory calibration, the auto calibration function is available in the Sound Kit. For determining the sound frequencies in the 'Spectrum mode' it is important that the clock runs at the correct frequency of 8 MHz (the clock is not divided by 8 by means of the CKDIV8 fuse).

For pre packed kits the auto calibration has already been done, so it only needs to be performed when you are programming the microcontroller yourself.

The auto calibration uses an external signal as an reference:

Frequency: 1 kHz
Amplitude: 3 V (signal low 0 V, signal high 3 V)
Shape: square wave

Auto calibration procedure:

Remove the power from the PCB.
Connect the external 1 kHz signal between pin 9 (PB6) and ground at pin 8 (GND).
Connect pin 10 (PB7) to ground somewhere (for example pin 8 or pin 22 or another ground on the PCB).
Supply the power (3 V) to the PCB again.
The Sound Kit will now perform the auto calibration for about 15 seconds. The calibration found will be stored in EEPROM so it will also be available after a power loss.
When the auto calibration is ready, the "disco mode" will start automatically.
Remove the external signal from pin 9 and the connection on pin 10.

Pin 14 (PB0 / TP1) outputs a square wave signal which (at an exact internal clock frequency of 8 MHz) toggles every 64 µs, and thus provides a 7.8125 kHz square wave. By monitoring this point the calibration can be checked. During the auto calibration you can monitoring the 'search algorithm' for the correct calibration value.