Hardware

The circuit of the box and its printed parts. The key data of the components and the links to their data sheets are in docs/hardware/.

The box put together from its printed parts, as a slightly simplified 3D model.

Folder	Content
circuits/	the circuit of the box, drawn with Fritzing: tinyjukebox.fzz, its picture tinyjukebox_circuit.png and the parts list tinyjukebox_bom.html
3d-parts/	STL files of the printed parts (December 2019), each with a picture of the same name: two views, the size in mm

1. Circuit

The circuit built, inside the lid of the first box (2019): the RC522 in its holder, the buttons, the LED and their resistors, the ribbon cable to the Pi.

Part	In the drawing	Connected to
RFID reader RC522	U6	SPI0 with CE0 (GPIO 8, 9, 10, 11), RST on GPIO 26, IRQ on GPIO 5, 3.3 V
Audio Amp SHIM with speaker	U10, SP1	GPIO 18, 19, 21 (I2S), 5 V and 3.3 V
Buttons	S1, S5, S6, S7	GPIO 6, 23, 24, 25 against GND, each with a pull-up resistor of 2.2 kΩ to 3.3 V (R4, R6, R8, R10)
RGB LED, common cathode	LED1	green on GPIO 27 through 2.2 kΩ (R2), blue on GPIO 17 through 220 Ω (R3), red on 3.3 V through 330 Ω (R1) and switched by the transistor Q1, whose base is on GPIO 22 through 4.7 kΩ (R13)
Power	U1, S8, U8, U2	the power bank (U1) feeds the Pi (U8) through the switch S8; U2 is a USB socket on the power bank

What to know about the drawing:

• The computer is drawn as a Raspberry Pi Zero. The box has a Raspberry Pi 3 Model B; its header has the same pins.
• The transistor Q1 takes the current away from the red LED while GPIO 22 is high: red is on while the pin is low. Green and blue are on while their pin is high.
• The buttons have a pull-up resistor each. The software switches on the internal pull-up of the Pi as well and debounces the buttons itself.
• The IRQ pin of the RC522 is connected to GPIO 5. The box does not use it.
• The switch S8 cuts the power between power bank and Pi: that is how the box is switched off.

The pins are those of the table in box.md, section 1, which also says what each button does.

2. Wiring

Keep the wires from the parts in the lid (buttons, LED, RFID reader) to the Pi a few centimetres away from the magnet ring of the speaker. Too close to it, the box may behave in undefined ways.

3. Printed parts

The case is made of wood; the printed parts are fixed to it.

File in 3d-parts/	Size in mm	Part	Photo
lid.stl	110 × 110 × 20	round lid with a hole in the middle; on the outside the outline of a unicorn and four hexagonal recesses with their symbols, on the inside posts and two brackets
lid_inlay.stl	77.8 × 78.5 × 0.7	the unicorn and the symbols of the lid as a part of their own, for a second colour
front_panel.stl	139 × 139 × 1	square panel with a round field of holes for the speaker
front_grille.stl	139 × 139 × 4	square grille of rings, with four eyes for screws
power_bank_mount.stl	123 × 91.5 × 15	frame for the power bank, with four posts and two rows of slots
rfid_reader_holder.stl	52 × 23 × 5.8	plate with a rail and four holes, for the RFID reader
usb_port_bezel.stl	44.5 × 15 × 2	bezel with an opening for a USB port and two countersunk holes
lock_screw_bracket.stl	30 × 10 × 10.5	bracket with an eye for the screw that closes the case
foot.stl	35 × 30 × 21.7	rounded foot with a hole for its screw
spacer_3mm.stl	5 × 5 × 3	spacer ring with a hole of 3 mm
figure_base_cup.stl	28 × 28 × 8	base of a figure, outer part: a cup, 26.2 mm wide and 7 mm deep inside
figure_base_plug.stl	26 × 26 × 7	base of a figure, inner part: the disc that fills the cup
figure_base_wide_plug.stl	32 × 32 × 8	inner part with a rim of 32 mm, for a wider base
figure_base_wide_cup.stl	28 × 28 × 8	the cup of the wider base; the same shape as figure_base_cup.stl

4. Licence

• Printed parts (3d-parts/): our own designs, under the MIT licence of the repository (LICENSE.txt).
• Circuit (circuits/): our own drawing, made with Fritzing. The graphics of the parts in it come from the parts library of Fritzing, which is under CC BY-SA 3.0; the drawing, its picture and the parts list are therefore under CC BY-SA 3.0 as well.