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Signal build

VU meter

Start with the video, then use the science notes and recommended parts below to follow the idea behind the build.

Radio & soundBuildAudio

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How it works

What this project is testing.

Sound is pressure in the air, but inside audio gear it becomes a changing voltage. A VU meter turns that invisible signal level into something your eyes can follow.

Read more

The experiment demonstrates how an audio waveform can be smoothed into an envelope and mapped onto a moving display, so louder moments light up more of the scale.

L_{d B} = 20 lo g_{10} (\frac{V}{V _{r e f}})

A handy way to compare signal voltage levels on a scale that matches audio work better than raw volts.

Recommended parts

Products used in this project.

Affiliate links may earn Keystone Science a commission. Match ratings, values, sizes, polarity, and safety requirements to your own build before buying.

BOJACK 3 Values 130 Pcs Solderless Breadboard 4 Pcs 830 Tie Points & 400 Tie Points & 126 Pcs Flexible Breadboard Jumper Wires

breadboardprototyping

BOJACK Solderless Breadboard Kit with 830/400 Tie-Point Boards and Flexible Jumper Wires

$9.994.4(692)

ElectroCookie Large PCB Prototype Board Kit Solderable Breadboards for Electronics Projects Compatible for DIY Arduino Soldering Projects, Gold-Plated (6 Multi-Pack, Blue)

printed circuit board / PCBprototyping

ElectroCookie Large PCB Prototype Board Kit, Solderable Breadboards for Electronics Projects

4.8(111)

EDGELEC 120pcs Breadboard Jumper Wires 20cm Wire Length Optional Dupont Cable Assorted Kit Male to Female Multicolored Ribbon Cables

jumper wires / hookup wirewiring

120pcs Breadboard Jumper Wires, 20cm Dupont Cable Assorted Kit, Male to Female

$6.984.7(4,500)

BOJACK 1000 Pcs 25 Values Resistor Kit 1 Ohm-1M Ohm with 5% 1/4W Carbon Film Resistors Assortment

resistorpassive electronics

BOJACK 1000 Pcs 25-Value 1/4W Carbon Film Resistor Assortment Kit, 1 ohm-1M ohm

$9.994.7(4,500)

CHANZON 100pcs 5mm LED Diode Lights Assortment 10 Colors x 10pcs Diodes (Clear Transparent Lens) Emitting Lighting Bulb Lamp Assorted Kit Variety Color White Red Yellow Green Blue Orange UV Pink

LEDsemiconductor

100pcs 5mm LED Diode Lights Assortment, 10 Colors

$6.994.5(1,800)

BOJACK 12 Values 120 Pcs Opamp Timer Darlington Phototcoupler LM324 LM339 ULN2003AN ULN2803APG LM358P LM386 LM393 NE5532P NE555P UA741CN JRC4558D PC817 IC Assortment Kit

integrated circuit / ICsemiconductor

BOJACK 12 Values 120 Pcs Opamp Timer Darlington Phototcoupler LM324 LM339 ULN2003AN ULN2803APG LM358P LM386 LM393 NE5532P NE555P UA741CN JRC4558D PC817 IC Assortment Kit

$18.994.8(511)

150 Pcs 15 Value 100 ohm- 2M ohm Trimpot Variable Resistor 6mm Potentiometer Assortment Kit

potentiometerpassive electronics

150 Pcs 15-Value 100 ohm-2M ohm Trimpot Variable Resistor Potentiometer Assortment Kit

$11.994.6(267)

BOJACK 20 Values 200 Pcs Inductor 10 uH to 10 mH 1 W Color Ring Inductor 1 Watt Assortment Kit

inductor / coilpassive electronics

20 Values 200 Pcs Inductor Assortment Kit, 1uH to 4.7mH, 0.5W Color Ring Inductors

$13.994.8(182)

Syncwire 3.5mm Nylon Braided Aux Cable (3.3ft/1m,Hi-Fi Sound), Audio Auxiliary Input Adapter Male to Male Cord for Headphones, Car, Home Stereos, Speaker, iPhone, iPad, iPod, Echo & More – Black

audio source / phoneaudio

3.5mm Nylon Braided Aux Cable, Male to Male, 3.3ft

$7.994.6(119K)

Use with an existing phone or audio player.

SUNYIMA 10pcs Mini Monocrystalline Solar Cells Solar System Kit 50mm X 50mm/1.96" X 1.96" 2V 160MA for DIY Charge Solar Panels

solar cell / photovoltaic panelpower

SUNYIMA 10pcs Mini Monocrystalline Solar Cells, 50mm x 50mm, 2V 160mA

$15.994.5(284)

Joytech Bluetooth Music Tesla Coil Arc Plasma Loudspeaker Wireless Transmission Experiment Desktop Toy Model SSTC SS02

Tesla coilhigh voltage

Joytech Bluetooth Music Tesla Coil Arc Plasma Loudspeaker Desktop Toy Model

$49.994.2(911)

High voltage/RF project. Prefer enclosed educational kits and add safety warnings. Review requirements and safety guidance before buying.

ZENY 3.5CFM Single-Stage 5 Pa Rotary Vane Economy Vacuum Pump 3 CFM 1/4HP Air Conditioner Refrigerant HVAC Air Tool R410a 1/4" Flare Inlet Port, Blue

vacuum pump / fridge compressorvacuum

3.5CFM Single-Stage 1/4HP Rotary Vane Vacuum Pump

$68.994.5(3,800)

TOSHIBA EM131A5C-BS Countertop Microwave Ovens 1.2 Cu Ft, 12.4" Removable Turntable Smart Humidity Sensor 12 Auto Menus Mute Function ECO Mode Easy Clean Interior Black Color 1000W

microwave ovensalvage

Toshiba EM131A5C-BS Countertop Microwave Oven, 1.2 Cu Ft, 1000W

$148.994.4(32K)

Recommend only as an appliance; do not encourage buying a working microwave for disassembly. Review requirements and safety guidance before buying.

BOJACK 10 Values 250 Pcs A1015 BC327 BC337 C1815 S8050 S8550 2N2222 2N2907 2N3904 2N3906 PNP NPN Power General Purpose Transistors Assortment Kit

transistor / MOSFETsemiconductor

BOJACK 10-Value 250 Pcs PNP/NPN General Purpose Transistor Assortment Kit

$8.994.7(763)

ShillehTek Pre-soldered 3.5mm Stereo Audio Jack Breakout Board – TRRS Headphone/Video Jack Module for Arduino, Raspberry Pi,

3.5mm audio jackaudio

3.5mm Stereo Audio Jack Breakout Board with Screw Terminal

$8.39

Functional breakout pick; verify mono/stereo wiring and connector style. Review requirements and safety guidance before buying.

Project files

Prints, kits, and downloads.

Diagrams, printable files, kits, or companion downloads will appear here when they are ready to use.

Coming soon

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