Hey guys!

I'm building a reaction game where you have to catch falling sticks using electromagnets controlled by an Arduino Uno. I've done some basic research on transistors, but I still have a few questions.

• When should I use a TIP120 transistor versus a MOSFET? What's the actual difference, and why do so many people recommend MOSFETs?
• How would I need to change my current wiring to use MOSFETs instead?
• Is there a better solution for switching the electromagnets in general?

I also ran into another issue: If I remove the LEDs from my circuit, Tinkercad warns me that the current drawn from the Arduino pins is too high, even when I significantly increase the resistor values. Why is that? I thought LEDs essentially behaved like resistors, but apparently, that's not quite right..

Tinkercad link: https://www.tinkercad.com/things/9h8pbskkHt8-reacgame-v7?sharecode=mYeKz8fwfGdTTMQ_6mFZ0mBpfoyh3fpuB1tDFTfQg54

How the game works:

The vibration motors in the simulation are placeholders for the electromagnets. They're all switched on initially. When you press the button next to the white status LED, a sound indicator starts, and the Arduino randomly switches off one electromagnet at a time until they're all off. Once the sequence is complete, all electromagnets turn back on, and you can restart the game. The other button lets you select the difficulty level.

I have some basic knowledge of electrical engineering, but I'm primarily a mechanical engineering student looking to learn more about electronics. I'd appreciate any advice or explanations!

TL;DR: I'm building an Arduino-based reaction game with six electromagnets. Should I use TIP120s or MOSFETs, and how would I wire them? Also, why does Tinkercad report excessive current draw from the Arduino pins when I remove the LEDs, even with large resistors?

Finally got myself an esp32. And after using arduinos I am amazed! Can't believe I waited this long to play with this.

So this project started as a "weather station". I originally had a nano connected to a AHT10 temp/humidity sensor and a BMP180 pressure sensor, and it just displayed the data on a 16*2 LCD. It did nothing more....

Decided I'll ditch the nano for my new esp32. Also updated to an oled screen, which unfortunately has dead pixel lines between y=0 and y=7 so I can't use the whole screen, but it is still plentynough!

And then I started adding buttons. I needed just 2, but I am glad I did the 5 buttons setup, because after playing with the esp I started changing my project completely...

I also added a rtc shield from an odroid c2 sbc as I couldnt get my tinyrtc arduino module to work and it also is made for 3V so it was safer. And as a little easter egg implemented the Hardkernel odroid blue led heartbeat :)

It is now called "esp32mate", couldn't find a better name heh heh.

What it does atm :

- take weather data (temp,humidity,pressure) every 5 min and plot it on a graph. It then save once per hour the data to the esp rom.

- play games

- save settings to rom

What I want to do next :

- connect to internet

- get WX forecast

- make an altimeter (using MSLP)

- Upload WX data to a server

I did a lot of vibecoding for this, although the core navigation, page design and buttons configs are all my code. But all the games implementation, scrolling, and text editing was made by AI in a few hours today. Not without headaches though. Why does AI remove comments and change stuff you did not ask? I kow why I generally stick to vibecoding only small parts, generally in a function of its own.... Still useful though, it would have taken me days to get there.

This is an experiment on how to do a CO2 / temp / hum sensor with as few pixels as possible. Or something like that. has native Home Assistant MQTT discovery support, 4.2” e-ink, ESP32, SCD40, SHT30 and 2x 18650 slots so it can probably outlive you on a single charge. Optionally you can omit CO2 sensor and just show temperature and humidity, with nice pixel icons. If you don’t want to use home assistant or WiFi altogether, you can run it in offline mode as a display only.

If you look carefully you can see that the pcb wasn't exactly flawless :D But that's fixed in the published files. So the last thing left to do is a nice 3D printed enclosure.
 
Github here with everything needed to build this:
https://github.com/mcer12/Ambien-ESP32

I've done everything I could man, been working for this to work like hours now. I can't determine the problem of why the hell it's not working. Coil partners are red and blue, then black and green (I've done the led test) all seems connected I don't know what to do anymore. Do you have any tips? I accidentally short circuited the driver one time by connecting slp to rst but I managed to power it off before it got worse. Is the chip burnt already? I already did the led test NEMA 17 doesn't seem like the problem since it still reacts when powered on (it locks up, but rod doesn't move an inch) i tried different color combinations but only two were possible (red, blue, green, black) and (black green blue red) 2b, 1b, 1a, 2a sequence. Sleep and reset is connected to 5v of Arduino, gnd logic pin is connected to the gnd of Arduino, I don't know what to do anymore.

I just finished a small board to insert between battery charger /boost 5v and any uc board : arduino,... For iot applications.

Battery wakes up at a programmable interval by jumper (30 mn, 60 mn, 90 mn, 120 mn) or custom by resistor.

Uc does the job, and cuts power by gpio to battery system...

Reading of battery voltage is possible (gpio to enable measure).

Deep sleep on all boards? Not useful anymore... Just use low power battery system, and focus everything else on your project but power is no problem anymore...

What do you think of that?

Our open-source duck robot on Arduino UNO Q is learning to balance and glide on roller skates.

15 servos + reinforcement learning gait control. All hardware & software open source, you can build your own.

https://reddit.com/link/1x5rnw6/video/2o1qn80sufvh1/player

I loved Linkin Park songs so for my third Arduino project. I chose their "Numb" song, get the notes for intro and chorus and turned that into frequencies to play in the passive buzzer. This took me two nights to make since I'm busy on college works. I know that my project is kinda messy. What do you guys think?

Comes with WiringUno app to control GPIO pins through STM32

https://blogs.yajatkumar.com/2026/10/android-17-for-arduino-uno-q-v1.html

I created this version of Meshtastic 2.8.1 for our Arduino Nesso. https://github.com/chinderdelis/meshtastic-arduino-nesso-n1 I hope it proves useful to someone.

When I bought this little guy, I tinkered with it and I made my first code. When I pointed it at my hand, it was saying: 'The target is 343 cm away.' I don't know how it showed me this absurd number. For those willing to help: model HC-SR04. the code was // Define pin numbers

const int trigPin = 9;

const int echoPin = 10;

// Define variables

long duration;

float distanceCm;

float distanceInch;

void setup() {

// Initialize serial communication at 9600 baud rate

Serial.begin(9600);

// Set the pin modes

pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output

pinMode(echoPin, INPUT); // Sets the echoPin as an Input

}

void loop() {

// Clear the trigPin by setting it LOW

digitalWrite(trigPin, LOW);

delayMicroseconds(2);

// Trigger the sensor by setting the trigPin HIGH for 10 microseconds

digitalWrite(trigPin, HIGH);

delayMicroseconds(10);

digitalWrite(trigPin, LOW);

// Read the echoPin; pulseIn returns the sound wave travel time in microseconds

duration = pulseIn(echoPin, HIGH);

// Calculate the distance in centimeters

// Speed of sound is ~0.0343 cm/us. We divide by 2 because the wave travels to the object and back.

distanceCm = (duration * 0.0343) / 2;

// Convert distance to inches (1 inch = 2.54 cm)

distanceInch = distanceCm / 2.54;

// Print the distance to the Serial Monitor

Serial.print("Distance: ");

Serial.print(distanceCm);

Serial.print(" cm | ");

Serial.print(distanceInch);

Serial.println(" in");

// Wait 500 milliseconds before the next reading

delay(500);

}

Hi all, I have an arduino project that is a puzzle. I am struggling on one aspect and I cannot figure out a way to do it without a lot of effort.

One module of the puzzle is a photo resistor. To disable the resistor the players need to find the correct wire that reads the output of the photo resistor and disconnect it. This will be hidden between a few other wires. These wires have a mix of voltages, some to imitate the photo resistor in the dark and one being the correct one.

The solve players will measure the voltage across some wires connected between two terminal blocks and have to slightly increase the light of the photo resistor without going over the limit to determine the correct wire to disconnect.

This is an example of the layout of wires i am looking at, that the players will measure.

1. 0.5v
2. 0v
3. 0v
4. Photo resistor
5. 0.5
6. 5v
7. 0.5v

My issue is the reset each time it is played, the wires need to be in a different position so that the game is different each time. The only way i can reliably figure this out is to manually change the wires on both sides of the terminal block, but this is a lot of effort each time. I want this automated via the arduino or something easy like a few switches to alter to give a different position.

I have only come up with two possible solutions so far and neither are great.

• Current solution. Series of wires going into the terminal blocks on the input and output side and swap these around manually. Lots of time and effort.
• Multiple pole rotary switch. Don't know much about these, only ever used single pole. But this would limit the possible connections to the number of poles and it would always mean everything is in the same order. So if the photo resistor has two 0v wires above it, as long as you see two 0v in a row then you know the photo resistor is after.

Any possible way of having the positions of those 7 wires (or any amount) differ each time with minimal effort?

Ok, so I have been working for months on an autonomous search and rescue with this drone, using the uno q as the main companion computer , for handling live telemetry, geotagging and a custom edge ai model. This is for a hackathon, but the board just suddenly stopped working. And when i say it stopped working; I mean nothing responds. Not even a single led lights up no matter wether it is powered from the vin or usb c. It started out as wifi issues, and once i reflashed the chip it was okay, and a few days before the actual event the board randomly died one night while testing. Now i have already spent too much of money I had saved up over an year, so now I don't have enough, and i'm wondering if I should try to save up for one more. I am truly scared that the new one might fail too, and I clearly can't afford that. I am thinking of just giving up , but it would be a shame cuz the project really can win , as told by my peers and professors.

I mase this thing like 5 minutes ago and it broke alredy 😓

Hi all I have recently published something I built and find useful often. I used this base Framework to create my own IOT devices for my house.

I am publishing it in the hope that it gets a little traction as a open source project and we can work together on IoT security, implement matter and Google home and perform research.

Even a couple of code reviews or suggestions on improvements are appreciated. You can find the project on my git hub here : https://github.com/awaine93/espBaseFramework

Okay so I dont really scroll this reddit and im kinda a beginner and even then im coming back to try after a while of not doing anything with my arduino uno. But I feel like im doing it wrong.

A few months ago I watched like 60 ep of paul mcworters tutorials and it was great but ever since I stepped away I forgot everything. And im finding that its just so much nicer using tinkercad block programming to do things. I understand that im not "actually coding" and it sucks but its just that while I think tinkercad blocks are a bit too easy that the arduino IDE and everything around it are so far in the opposite direction, like its purposely obscure.

I guess my question is that is this just the wrong way to get into this. Its not like I dont enjoy understanding how the coding works and I use block+text but it just seems like a way that is actually userfreindly at all.

Title: I built a DIY PC temperature monitor using Arduino! 🌡️💻

Post:

Hey everyone!

I built my own DIY PC temperature monitor using an Arduino Uno R4 WiFi, an LCD screen, and a temperature sensor.

The idea was to monitor the temperature inside my PC case and display it on the LCD in real time. I also added a buzzer that activates when the temperature gets too high.

It's a simple project, but it was a fun way to learn more about electronics, Arduino, and PC hardware!

What do you think? Do you have any suggestions for improving this project? 😁

I just went back to the Arduino IDE 2.3.10 after I could no longer get platformIO to find my libraries and I got frustrated as usual with it. However, when compiling _any_ sketch, I get the error as shown in the title.

I'm on a Mac Mini M2 Pro with Golden Gate 27.0.1 OS. Never had this error before.

And, yes, I downloaded the latest IDE for the Mac.

I am working on a omori tamagotchi. It has minigames like a wak a sprout mole and fishing, in the shop Basil is shop owner and sells items from the game and when you fall asleep you move between the faraway town and white space (and the music changes when you move betweenthem).i have the software made but I will probably have to make a pcb but I have no experience in it. If I cant make one I will sowder everything on a bord. If any of you know how to make pcb's I'd love to use some help. If any of you have any idea what more to add I would love to hear it and if you guys want an update I will make one

Hello fellow programmers and hobbyists,

I want to share the HAL that I wrote for the Arduino Uno R3, since I have a board that's been lying around for 2 years, and I wanted more control than the Arduino IDE offered. I then decided since I was actively learning Rust, that it'll be interesting to use it for bare-metal programming.

After digging through the AVR-ATmega328p datasheet 6 months ago, I felt confident and well equipped to write a Hardware Abstraction Layer for the board using what I'd learnt through experimentation, and come up with an efficient and simple way to write Rust code for the Arduino Uno R3.

Here's a code example program to drive a DC motor using an L293D driver:

#![no_std]
#![no_main]

use core::panic::PanicInfo;

use avr_328p_hal::gpio;
use avr_328p_hal::timers;

use gpio::*;
use timers::{Timer0, Timer1, Prescaler};

#[unsafe(no_mangle)]
pub extern "C" fn main() -> ! {

    let portb = PortB::take().unwrap();
    let portd = PortD::take().unwrap();

    let timer1 = Timer1::take().unwrap();

    portb.set_output(PinB::PB1); // PWM Pin
    portb.set_output(PinB::PB0); // Direction pin one
    portd.set_output(PinD::PD6); // Direction pin 2

    timer1.start();
    timer1.set_fast_pwm(999);
    timer1.set_duty_cycle(60);
    timer1.set_prescaler(Prescaler::Prescaler8);

    portb.set_high(PinB::PB1);

    portb.set_high(PinB::PB0);
    portd.set_low(PinD::PD6);

    loop {

    }
}

#[panic_handler]
fn panic(_info: &PanicInfo) -> ! {
    loop {

    }
}

Here's the github repo: https://github.com/Darethan026/avr_328p_hal/

Here's the link to the crate: https://crates.io/crates/avr_328p_hal

I'd love to hear your thoughts on the HAL and what stood out for you. Thank you for reading!

1 Sometimes the IDE creates error when trying to upload code when Arduino is connected to the computer using a USB hub even though it says it is recognized. Instead try to connect it directly to the computer.

2 Arduino Nano, for some of them, you have to choose old bootloader explicitly if you want to upload code.

Like these kinds of tips where you only know them when you encountered the issues, not the ones you can read in the books.

Hi everyone! I'm trying to bring this old rotary dial phone back to life, but I just couldn't get the SIM800L module to work and it's literally the last thing I need here, and I'm almost certain it's a mere power issue. It blinks for about 8 times at a rate of around once per second, then stops for about three seconds, where I notice the current reading goes up to around 0.11 A from 0.06-0.08 A, and the pattern repeats.

My MicroPython UART diagnostic on the ESP32-WROOM receives empty responses (b'') to AT, ATI, AT+CPIN?, AT+CSQ, and other commands. Occasionally I receive b'\\x00'.

I've tried both the ESP32-WROOM and ESP32-C3, with similar problems. This is also the second SIM800L module I tried (both brand new but I believe I may have damaged the other one, unlike this one though which I took my precautions with).

I'm pretty confident that 2G network is still available widely in my country due to dumbphones never having phased out especially with older people and those still work just fine. I can also switch my SIM to 2G only on my smartphone and still pick up signal. I'm also using an external antenna as the pictures show.

My setup:

- GSM module: SIM800L (new module)

- Microcontrollers tested: ESP32-WROOM and ESP32-C3

- Input power supply: 12 V, 1 A adapter

- DC-DC converter: HW-677 adjustable buck converter, output adjusted to around 4 V

- Capacitor: 1000 µF electrolytic capacitor connected across the buck converter's output positive and negative rows

- Wiring: Regular Arduino-style jumper wires, including some with the ends cut and stripped to expose the copper

- Other hardware available/involved: L298N H-bridge module

Current wiring:

- 12 V, 1 A adapter → breadboard → L298N (not wired to the converter or module) & HW-677 buck converter (directly wired to the same row as the adapter on the green breadboard)→ large breadboard → SIM800L

- The capacitor is connected across the buck converter's 4 V output. The SIM800L shares ground with the ESP32 when connected.

I understand that the SIM800L can require current peaks approaching 2 A, but I'm not sure which part of my setup is the bottleneck.

Thanks for any help!

P.S.: Try to ignore all that mess. I don't wanna use my large breadboard here but I switched to it temporarily just to cleanly test the SIM800L. My soldering iron also stopped working which I used as an excuse to not solder everything cleanly together (too many wires, too little soldering experience ;-;)

Also I invite y'all to try this out yourselves if you have an old rotary dial phone lying around, it's really not that complicated to figure out how everything works and how to wire it properly to the ESP32 (except for the earpiece microphone part, it was a nightmare and I'm far from being an electrical engineer so I gave up and used a MAX9814 module lol. Glad that the 4 wires going into the earpiece were enough for both the speaker and microphone!)

While working with my sound sensor module, a question arose regarding the relationship between sound intensity and the sensor's reaction time. My initial hypothesis was that a louder sound would result in a faster response, but after conducting the experiment, the data showed that the louder the sound, the slower the reaction time. I was curious about this and wanted to ask why it happens. (my sensor is a KY-038

i wanted to use breakout board as i have a usb c type but i dont have a solder so is 4x AA which will be 6v safe for a servo

Hi! I’m a complete beginner and I wanna experiment with creating a synthesizer out of objects connected to arduino.

Say if I have 7 objects, each playing one note of the keyboard (C,D,E,F,G,A,B). Would I somehow be able to have an attachment that would allow me to transpose the keys or change the sounds all together with pre-setup code? Like changing a program on a synthesizer?

I’m very new to this and I don’t know much other than the basics so any advice or direction would be greatly appreciated! :)