Built this for a Halloween challenge on element14.

The idea was that the doll moves its head when nobody is in the room, and freezes when someone comes back. I used an M5Stack AtomS3R and an SG90 servo. The CSI part runs on the ESP32 and uses changes in wifi signals to detect movement.

No PIR sensor or camera for the detection. It sends pings to the router and reads CSI from the replies.

Had to do some tuning. Walking is easy to detect, someone sitting still is a different story. It also detects movement in the hallway behind a closed door, depending on placement.

I made a Python version of the detector too, so I can replay recorded data and see what happens with the subcarriers and thresholds. There is a scope for that in the repo.

Project write-up, video and build details:
https://community.element14.com/challenges-projects/halloween/a/projects/PR186/nobody-home-the-cursed-doll-that-only-moves-when-you-leave-the-room

Code:
https://github.com/apn201/nobody_home

Video:
https://www.youtube.com/watch?v=jTFQheh9W2k

Has anyone else tried CSI for presence detection? Curious how well it works for people sitting still.

So I got this headphones Sony M5 they are great but the join got broken and I didn't fix it. I was just using it with the broken join and one day one thing led to another the wires you see in the picture got twisted and cut so I don't know how to rejoin them. Is it possible or should I buy a new one? I placed the usb stick for perspective

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This design uses two BC548 NPN transistors to flash a ⚪ LED and a 🔵 LED alternately.

A few years back, just before COVID shut down most things, I was perusing eBay one day and found a salvage freight seller who had full reels of Cree 18V white LED chips (not strips) 3500K for ~$25. On a whim, I bought a couple of reels. That led to much experimenting about how best to use them. One of the discoveries was that they could be run down around 15.5-15.6 volts, get some light, and very low current consumption (1-2 mA instead of the 50 mA rating on the data-sheet). So I designed a couple of boards. Two designs were x100 LEDs on a 100mmx100mm board, and the other was a baby board (20mmx20mm). This is the first valid use for the baby board. The board consists of x5 2835 18v LED chips, one LM317LZ regulator and (on the backside) 3x 75Ω 0805 chip resistors (in series). The LM317LZ is configured as a two-terminal current regulator, the 2835 18v LEDs are all in parallel, the 3x 0805 chip resistors are in series and used to set the adjust voltage on the regulator (which in this case controls the current). Measured current is ~5.5 mA. The light is being powered by a Ryobi 18v 2 Ahr pack, so it will run for many hours before needing a recharge. Any 5S Lithium battery pack should be equally applicable. Additional images will be posted if possible. The enclosure is a pill container, with a 2.2mm hole drilled in the lid to get the wires thru it.

I don't know if this is the right sub since this is more of a physics question, but I want to build a simple device that can detect frequencies often emitted by electronic devices (so basically wifi frequencies) in order to locate them. To do this i'm guessing i'm going to need some kind of directional broadband antenna and from my deep research (looking on google), I think I understand that the simplest way to do with is with a V-shaped design. I want to keep things as simple as possible since my (rather optimistic) goal is to make it handheld. I already figured that a parabola would probably help concentrate signals, but that's as far as I got. I don't really know much about making antennas so any help is really appreciated. Thanks!

JIDU6101, Populating & Adding USB port

I have an Openwrt flashed JIDUb6101.

On usb qruery '

root@OpenWrt:\~# ls /sys/bus/usb/devices

1-0:1.0 2-0:1.0 usb1 usb2

There is an empty - unpopulated -unsoldered USB slot on the board .

Has anyine ever tried to venture soldering an USB adapter and make it functional

Kindly suggest

The inductor is 15 turns of 30awg(I think) wire around a 1 inch in diameter paper cylinder, the capacitor is 33pf, using a germanium diode to demodulate and the speaker are just a normal crystal earpiece.

Intro

I do CAD for a living but I am an absolute beginner in electronics. I saw the Kickstarter for the Syitren RM1 Bluetooth CD player a while ago, and it got me thinking. I will not be buying it or anything similar like the Coolgeek M1 as they use batteries and I absolutely despise recharching/swapping batteries. A dream of mine is owning a BeoSound 9000 someday, but in the meantime I'd love to design something myself that would combine a little of the designs elements of all the systems listed above.

My question

What parts would i need to make all this possible?

I thought about purchasing 5 or 6 PlayStation 1 replacement optical drive heads and design around them. What i like about them is the availability and the 3 prong type cd holder they come with. For the rest I am clueless. How will i make the drive head communicate with a main board, allow for Bluetooth connectivity. I'd love a simple interface where i could just pick  a single CD out of the 5, press play, and it starts playing.

Any help will be appreciated!

tl;dr: I don't 'need' usb. It was just the easiest way to go. Looking for recs on a dev board/package that lets me wire up a speaker and a mic, with wifi and some storage for audio buffering.

I'm building a thing and I'd like to build a lot of the thing. (no, it's not actually YAAIAssistant. But it's close-ish.)

I've entirely frustrated myself in my attempts to use esps with microphones and speakers (and assume it's because I can't read specs or something. The esp series is amazing.)

Wired up a zero 2w with a usb mic and speaker. And the thing worked like a CHARM. Yeah, ALSA is a demon. But I've got it beat in to shape.

I get that the world (particularly our world) is bananas right now. But I'm not paying nearly $40 for a damn zero.

I looked at the "Pi-Alikes" the orange boards, etc. But they all seem to be plagued by the same forces. (Not surprising.)

If it weren't for my floundering with the INMP441s, I could use esp boards I have on hand. But I've gotten 1 in 11 to work.

Is there likely to be anything out there that fits this niche or should I just get my scuba gear and dive back into the esp32 troubleshooting?

Hey everyone!

I have an old Sony PSP, but I’m not sure about its generation or year of manufacture yet. I’m interested in repurposing it into something similar to Morning Blues’ live, immersive lyrics generator — something that displays song lyrics in a visually appealing, animated style while music is playing.

I’m wondering if this is technically possible with a PSP.

A few things I’d like to know:

• Can a PSP run custom software or homebrew applications to achieve this?
• Is it possible to display synchronized lyrics with animations or visual effects?
• Could it connect to a phone or PC to receive song information and lyrics?
• Would I need to modify the PSP’s firmware, or is there another approach?
• Has anyone attempted a similar project or know of existing tools I could build on?

I’m happy to experiment with the hardware and software. I’d appreciate any suggestions, tutorials, or project references that could help me get started.

Thanks!

I've been turning a Waveshare ESP32 board into a little desk device that plays my music, streams my radio and shows a few of my other projects.

I wrote up the full details here: https://radiowaveshare.vercel.app/

And here's a short video of where it's at: https://www.youtube.com/shorts/M8RFW_0WtDE

Some background: I already had a few web projects running, and I ported all of them to C++ so they run on the device:

• https://radiobananas.art/ where I stream my own music
• https://loor.news/ a news aggregator in Armenian
• https://trainspotting.vercel.app/ an artsy little thing I made

Next up I'm building an NFC reader so I can tap a card and it plays an album.

Happy to hear any feedback or ideas!

Hello guys!

I’ve been searching for the past 2 weeks for a free STL file or open-source project to build an off-road rover / RC car, but I'm struggling to find a chassis that fits my specific hardware layout.

Here are the components I plan to use:

• Microcontroller: ESP32
• Motor Driver: BTS7960 (High power)
• Motors: 4x JGA25-370 (12V, 100 RPM gear motors with encoders)

Does anyone know of an existing open-source design, 3D printable chassis, or a similar project that accommodates these components (especially the BTS7960 and 370-size motors)? Any links or advice would be greatly appreciated!

Thanks in advance!

Hello, I salvaged an E-Ink screen from a 2015 Kobo e-reader, but I don't know how to use it for my DIY projects. Here is the part number I found for the screen : ED060KG1.

Do you know which controller or other component to use?

Thanks in advance for your help.

When salvaging 18650 cells from old electronics, measuring the voltage seems like an obvious first step, but I'm wondering how much that actually tells you about the battery's condition.

A cell might show a reasonable voltage but still have poor capacity, high internal resistance, or problems that aren't obvious from the outside.

For those who regularly reuse salvaged cells in DIY projects, what's your testing process before deciding whether a cell is worth keeping?

Do you use a dedicated capacity tester, measure internal resistance, or follow a different set of checks? Also, what warning signs make you reject a cell immediately rather than risk using it?

I'd be interested in recommendations for affordable testing equipment and a sensible safety checklist for hobbyists.

First of all I wanted to say thank you knowing there's a dedicated community where I can ask this question.

I have 4 Solar Flood Lights that I bought and placed at the back and front of our house. It is a type of flood light that when its solar panel no longer detects sunlight it will automatically turn on. Its brightness is at 100% then after a few minutes it will automatically lowered to I think 70% or 50%. Because of that, its battery can only last for 3-4 hrs, what I do to prevent it from draining its battery is I manually lower its brightness to 10%, that gives me a 6-7hrs of light.

I realized, what if some of this flood lights only turn on when someone walked in, I can save most of its power. Like for example, if I have 2 lights back and front of our house, one of each is motion sensor so the other can stay on at its lower brightness while the other will only turn on when it detects motion.

I thought of just buying a flood light with a dedicated motion sensor, but its a waste of money if I already have one to modify.

I have a little background when it comes to electrical and electronics, but not confident enough to do it without asking questions from people with great experience.

So my questions, does anyone had already modify one with a motion sensor? Or is it possible to do it? All I can see on YouTube is people removing the motion sensor to keep their lights turned on.

(Picture indicated is the example of flood light that I have)

Thank you everyone!

Hi I’m trying to replicate the design for this breakout box. Could anyone help me identify what the plug contents are on the left and the red components on the right. I would greatly appreciate it

Thank you!

I printed my first Design.

STL files

Hey everyone. I wanted physical media shortcuts on my desk without cluttering up my setup with extra macro pads or buttons.

So I wired an MPU6050 accelerometer to an ESP32-C3 Super Mini, mounted the whole thing to the underside of my wooden desk, and connected it over Bluetooth. When you tap the table, the IMU picks up the shockwave.

I initially struggled with false triggers from typing noise, so I trained a small neural network classifier using Edge Impulse running locally on the ESP32 to tell the difference between a deliberate tap and normal background vibrations.

Now, a single tap pauses music, a double tap skips tracks, and four taps switch the profile over to volume control. Completely invisible and wireless on top. Let me know what you think!

I’ve set it up to display the stock tickers I’m interested in, along with the weather.

Switching dashboards or displaying different data takes just a few minutes. You can even create and switch between multiple dashboards.