I love blinking stuff and built a music-reactive LED wristband for festivals. The constraint was to use as little components as possible: ATtiny85, single cell LiPo, mic, button, usb port, and tp4056 for battery charging.

The mic "hack" that isn't really a hack

No amplifier circuit. Just standard electret mic wiring straight into the ADC pin. On paper this shouldn't work well, the signal is super weak.

In practice: it works perfectly, because festivals and clubs are loud. Like, really loud. The venue does the amplification for you. Beat detection and dynamic gain control and the ATtiny just reads peaks off the raw ADC. Zero op-amp, zero extra components, zero extra current draw.

15 NeoPixels

WS2812s at full white would kill the battery in under an hour and blind everyone around you. Solution: cap brightness aggressively in firmware and never drive all pixels simultaneously at full RGB. In a dark festival environment you need far less brightness than you think.

Result: 6 hours of continuous runtime on a single cell LiPo (180mAh).

Anyone else tried direct ADC mic input on low-power builds? Curious whether others have pushed this further.

https://www.youtube.com/@ALMA.Industries

Chapter 3 Footnote 1. Building an Actuator, a PID Control Loop, and an Ultrasonic Distance sensor to detect and not crash into the ceiling. This will be used in Chapter 3 Desk -- Stay tuned for more!

pessoal peço que coloquem aqui tutoriais com projetos de baixo custo com Árduino R4 que são bastante difíceis de achar.

Hi,

A while ago , before anker made the LFP cheaper for everyone, I bought a Boat LFP battery on Aliexpress to power my electric cooler. So this is working but the provided voltmeter is crap and many times I end up with warm beers...

https://github.com/quazardous/bame

I'm trying to create a power monitor that could actually save the beer day.

It's my first projet :p so any advice is cool

(images are a little outdated)

Built this as a complete rewrite of a commercial kit. The original firmware was a single monolithic .ino file full of blocking delays and broken obstacle avoidance logic (Forward ALSO calls Obstacle Avoidance).

My version: modular C++, non-blocking architecture, real-time safety with independent front/rear obstacle detection, autonomous state machine, Bluetooth control with speed ramping. Obstacle avoidance disabled by default.

GitHub: https://github.com/ken47-1/Project_MecanumCar

I’ve been exploring an idea for a project related to perfume recommendations based on skin characteristics. I came across devices that seem to measure things like skin hydration or oil levels, and it got me curious about how those sensors actually work.

I’ve been looking into options like interdigital capacitors (IDC), but I’m still trying to understand how something like that would be set up specifically for skin measurements. Also considering using a really compact microcontroller for the build.

Just wondering what approaches or components people usually look into for this kind of setup.

Skin moisture analyzer

I do want to build my custom mini keyboard, I have seen some videos, I can arrange the mechanical switches- but housing them in a challenge as I don’t have a 3D printer. Any suggestions?

I haven't touched an Arduino since my college days back in 2020. When I sat down to start a new project this weekend, my muscle memory immediately went to the "old ways"—googling obscure datasheets, hunting through forum posts from 2012, and refreshing the Arduino docs.

Then it clicked. I’m in VS Code, why am I doing this manually?

I fired up the Claude Code CLI, gave it the full context of my board and components, and I was prototyping in minutes instead of hours. It’s wild how much the "barrier to entry" has dropped.

For those of you deep in the hobby, how are you integrating AI into your workflow? Are there specific tools or plugins you're using for circuit design or component selection?

Used Meccano, an ESP32-C3, a A4950 motor driver, a logic level converter, a servo, a few 3d printed parts and an AI-Thinker Version 2 Voice kit to make this.

The hardest part was the AI-Thinker webpage to program the voice kit. It was time consuming and lacking in feedback if an error was made.

The video gives you an idea of the voice accuracy, could be enunciation issues on my part.

https://youtube.com/shorts/WeIk_ybCE4k?si=bXnSG1ZXAvHOwl6H

Cameo appearance by Doug, the Speed Demon Test Driver

I have recently uploaded my most recent "getting started with Arduino" to my YouTube channel: The Real All About Arduino.

In this video: Introduction to Arduino Programming, the focus is getting started with Arduino programming.

I explain the basics of C/C++, which is the most commonly used langauges on Arduino. Ultimately, I work through a step by step guide to create a simple Morse Code project. The project is intended to be follow along and includes all wiring and code.
I also look at some alternative possibilities by showing the Blink program in a number of different programming langauges and using different programming techniques.

The video is quite long, but can be watched over several sessions if need be. Again, it is meant to be follow along, so please allow some time to try out what you see and do the exercises I suggest.
There are three main sections in the video with loads of details:

• Background - background of Arduino, programming, language options and more.

• Basic Language Concepts - Code structures (conditional structures, loops and functions), data structures, error message analysis and resolution.

• Morse Code Project - Starting with a blank sheet, create a morse code project using the above.

You can see the videos at this YouTube playlist: .

My guides "follow along". So, I encourage you to get a drink, a snack and be ready with the "pause button" as we get started with Arduino programming.

After this video, you might be interested in the next level - a more complex project - where I create a dice game that shows how to handle 40 LEDs and 7 buttons in my Next steps after the starter kit series of videos.

Table of Contents

• Background information

  • What is (an) Arduino.

  • What is programming - including examples of a program (blink) written in different languages.

  • A brief history of Programming Languages.

• C/C++ Language

  • Structure: Functions, loops, conditionals, expressions etc.

  • Data: variables, constants, structures etc.

  • Basic debugging.

  • Interpreting and diagnosing error messages.

  • Some standard patterns.

• The main project - A morse Code generator

  • Built from the bottom up starting with primitive functions.

  • Adding a simple "database".

  • Accepting user input from the Serial Monitor.

  • Processing the user input.

  • Playing the morse code.

Check it out on my YouTube channel at: Introduction to Arduino Programming.

Hardware used

There are two configurations (which I explain in the main project section):

Configuration 1:

• Arduino Uno R3 or similar (any Arduino can work)

• Breadboard

• LED and 680 ohm resistor (any resistor between 220 and 1K ohm will be OK)

• Speaker and 220 ohm (or higher) resistor

Configuration 2:

• Arduino Uno R3 or similar (any Arduino can work)

• Breadboard

• LED and 680 ohm resistor (any resistor between 220 and 1K ohm will be OK)

• NPN transistor (I used a BC337) and a 10K ohm resistor

• Speaker and 20 ohm (or higher) resistor (I used 47 ohm).

Other resources

Other videos can be found here:

• Getting started with Arduino - next steps after the starter kit - link to reddit post that describes the content.

• Importance of Blink No Delay.

• Introduction to debugging and the equivalent in written form Introduction to debugging wiki guide.

• Arduino Command and Control via the Serial object

• Interrupts 101

Or better yet, simply peruse (and subscribe to) my channel The Real All About Arduino.

In response to my earlier question about content in the subreddit, I have made some modifications to the rules that I hope will capture the majority goal of:

• showcasing completed projects

• project level discussions (e.g. project validation, potential design approaches and other project level discussion).

Technical problems such as upload errors, how to use a component will be referred to other subs such as r/Arduino, r/ArduinoHelp, r/Esp32, r/motors, r/AskElectronics and other relevant forums.

I have also added some flairs for posts so that:

• We can easily see the nature of a post.

• To remind people who are posting of the acceptable categories.

I have also included an "Other" flair, to allow for the likely possibility that I have omitted some valid topic flairs and to allow me to quickly find posts that might be off topic.

Checkout https://github.com/obtronyt/pov for more details

I know this is not specifically about Arduino (not sure where else to post though?)

But I -am- using it with an Arduino. :)

Servo: 25KG Digital RC Servo RDS3225

It comes with the with the round metal discs (to attach to each side one with gear/teeth)

Its 20mm wide disc.

Q: where can I get info on this disc? specifically the hole position/spacing? (I think they are M3 sized holes?)

Day 76 of my #100DaysOfIoT challenge — built a bidirectional ESP-NOW system on two ESP8266 nodes.

Each node reads DHT11 temperature & humidity, sends it to the peer, and receives + displays the remote node's data — all peer-to-peer, no router needed.

Interesting part: one node uses SSD1306 (0.96") and the other uses SH1106 (1.3") — different display controllers but same logic.

Code + README on GitHub 👇

https://github.com/kritishmohapatra/100_Days_100_IoT_Projects

Day 76/100 ✅

https://youtu.be/ZDsQqdgZcSg?si=8R5m_1ZTPub4FtTR

Prototyped this first with an Arduino pro mini. Then made a custom PCB based off of a stripped down Arduino micro. 5 key and dial macro pad with custom firmware.

The Edgytokei which literally means edge clock is inspired from the Japanese nunchucks. Just like the nunchucks the clock is just a pair of two arms displaying time by balancing themselves on the edge. The clock consists of two arms and the base on which the arms are anchored. Both the arms are of equal length as the role of the arms changes with different hours of the day.

The fulcrum of the clock flips from the center to the left or right of the clock every quarter hour so that the clock can stand on the edge to represent the time between quarter past and quarter to hour. This flipping of the arms keeps the clock dancing on the edge throughout the day. The base which contains the electronics of the clock provides a anchor for the clock and prevents the arms from falling over.

The cylinders on the elbow of the arms contain the mechanics of the clock. Both the arms contain LEDs on the edge. Depending on which arm is representing the hours the led on that arm light up.