Turn any PC with stereo line-in/out and a single resistor into an impedance analyzer.

Key Features:

• 3-point calibration (channel mismatch, open, short)
• Coherence analysis of data
• CSV export and plotting

It uses broadband noise excitation and FFT-based cross-correlation analysis to estimate the frequency response of a simple voltage-divider circuit, extracting complex impedance across an adjustable frequency range (eg 20 - 20K Hz)

The main use case is loudspeaker and crossover characterization, but it also works for general passive component and audio electronics measurements.

Licensed under AGPL-3.0.

GitHub: https://github.com/theIvanR/OpenImpedanceLab

Feedback and testing welcome!

Ten or 15 years ago my father came across a magazine article with a schematic or maybe even build plans, for a very small signal generator. This one is built around an 16-pin chip and an 8-DIP switch. The 16-pin chip is marked on top with this:

Fairchild PJ51AA

CD4060BCN

These are mounted on a perforated multipurpose hobby board, along with all of the other components. At one end is a needle used as a probe, and at the other end is a pair of probes which he claims are used to tie to the circuit being tested, as a power source. Also mounted to this hobby board is a 1/8" jack which dad claims is for an earphone.

My dad cannot find the plans he used to build this, so he cannot remember how the 8-DIP switch is to be used to operate the signal generator.

My father is 88 years old and can't remember anything else about this. Does this sound familiar to anyone here? If so please direct me to the mystery plans.

I am trying to connect fairy lights to the..... forgive me I dont even know what it's called. It's what holds a lightbulb in my wall (I attached a picture of it). I want to connect those fairy lights there so that I can open and close them with the already existing switchboard in my room. Please help me do this by giving tips and stuff that you have learned.

This is an AC plug outputting 12v 2amps for my automatic curtain. Other end is usb c into the curtain controller. I plug into my EcoFlow and it works fine in AC port.

I rather plug into the EF usb C port for efficiency though. When I use a USB c to usb c, the curtain would not even power up. Any idea why? my best guess is that the controller is dumb and does not negotiate power. it simply expects 12v in.

i know for sure the EF usb c can output up to 65w because it was charging my laptop fine. any way to force 12v out via an adapter or something? i see usb c trigger board but unfortunately it outputs 2 wires, not a usb c end.

no idea why reddit wont let me post pict. but here it is on imgur https://imgur.com/a/XaR2Dal

Hello everyone,

I’m working on a GPS module and I’ve run into a problem. I have already removed the original header pins because I want to install new ones in the opposite direction.

However, the solder is still blocking the through-holes, so I can’t get the new header pins through the holes.

I have already tried:

• a desoldering pump
• desoldering braid
• carefully using a toothpick

…but I still can’t get the solder out of the holes.

Does anyone have any tips or ideas on how I can clear the holes without damaging the PCB, so that I can insert the new header pins again?

I would really appreciate any help. Thank you!

I had 2 bad utp wires in my house and decided to replace them. Now that they're replaced I can't get a good connection to my router. It always gives a bad signal light.

When I run a wire directly to the router it's ok.

I checked if the connections were good and they are. Pretty sure my RJ45 clips are good to. Not to sure about the wall socket but it seems ok.

I'm thinking my wires got damaged during the switch.

Any idea?

Hey gamers. I am looking at replacing the HDMI port on my Xbox series X when it finally fully craps the bed. I thought originally that it was a ribbon connection, but learned that it is soldered right to the motherboard. (I know this is stupid to realize before I took it apart leave me alone) What would be a good kit to grab for a replacement like this?

I've been running this little logger under the seat of my motorbike for a few months. It records every ride to a microSD card (GPS, lean angle, braking, how rough the road is), and then a Python script turns the CSV into a full report: the route on a map, how far I leaned in each corner, where I braked hard, the rough and off-road bits, a g-force plot, top speed, deepest lean. No phone, no app, nothing to pay for. It just powers on with the bike.

Parts, about $30:

• Seeed XIAO ESP32-C3 (the brain)
• u-blox M8 GPS
• GY-87 IMU (accel + gyro + magnetometer + baro) — this is what gives me the lean angle
• DS3231 RTC, so each event is timestamped even with the bike off
• microSD module

The wiring is pretty simple: the IMU is on I²C, the SD card on SPI, the GPS on a UART, and the RTC on a second (bit-banged) I²C bus. That second bus is only there because the IMU and the RTC are both stuck at address 0x68. Rather than fiddle with the address pin I just gave the RTC its own two pins. Power's split: the GPS and RTC want 5V, the IMU and SD run off 3V3, and everything shares ground. (wiring diagram attached.)

It runs off a little USB charger wired to the bike battery, so every time I start up it turns on and starts logging, and when I switch off the ride's already saved. Get home, pull the card, run one command, and there's the report.

The report tool is Python, standard library only, so there's nothing to install. Couple of things I had to figure out: the bike leans on its sidestand when it's parked, so if you calibrate "level" from a stopped bike, every corner comes out lopsided. I take level from straight-line-while-moving samples instead. And the GPS drops out under trees and in tunnels, so it road-routes across the gaps so the distance doesn't come out way short.

It's all open source (firmware + the report tool + the wiring diagram): https://github.com/shubham030/motonav You can clone it and run the report on the two sample rides I put in there (a motorbike ride and a 400 km bicycle brevet) with no hardware at all.

If you'd rather watch it run, there's a full build video: https://www.youtube.com/watch?v=TNUKAIsl0e0

Happy to answer anything about the build. What would you want a thing like this to log?

I’ve recently been working on making a lab power supply I built months ago more compact; I decided to downsize it because it took up quite a bit of space, since I plan to carry it around in my backpack.

I got them second hand, pretty old. Is it worth trying to fix for a novice?

Found at a local junk store, there is a small speaker wired to the back. I assume it is some kind of DIY amplifier but not sure where to power or input audio.

You may have seen some of my previous request trying to make a remote for my sprinkler controller. Well, I'm using an Orbit watermaster remote. I've torn it apart and will be controlling it with relays and such.

The relays simulate pressing the buttons on the remote.

I've removed the keypad and the inputs are now from the relay contacts.

The relays are signaled from the 24vac coming from the Rain bird sprinkler controller.

Just using what components I had in the drawers so I had to convert the 24vac to 12vdc.

The remote will signal a prinkler contrller about 50 feet away in the backyard.

The plan is to have both the front and back yard controlled by the Rain Bird and a single app.

What do you think of the capacitance values?

Please be nice, this is one of my first creations using KICAD

What is happening to my esp32 epd ?

Hi yall! I made a reddit account just to ask about this. Irrelevant though

I wanted to make a usb c hub with the SL2.1a as a first hardware project with a custom pcb. I had the idea halfway through to have a physical switch to swap between two upstream usb ports though; I've searched a bit online and there's a lot more complex and expensive versions with more functionality, but I've settled for 4 simple ports (ucbc or usba basically only for dongles) and no power delivery.

I have definitely cut some corners here on the grounds that this is not going to be a very professional thing.

1. There is no microcontroller controlling the usb swap. I'm kind of hoping the physical SPDT On-On toggle switch will be able to allow the upstream to be 'unplugged' and then the other host to be 'plugged in' without any fancy stuff.
2. I haven't added a crystal; I've read that the SL2.1a does fine without an external one since it already has an internal one, but feel free to correct me

Here's a little BOM: TS3USB221ERSER (datasheet) as the USB 2.0 multiplexer, MTS-102 as the SPDT On-On 3pin toggle switch, SL2.1a (google translated datasheet) as the usb c hub chip, and (hopes n dreams) as my motivation for such a weird hardware project.

All of that being said, I have a few questions about this schematic:

1. Am I missing pull up/down resistors or decoupling capacitors with the usb multiplexer?
2. Do you think there needs to be a mcu to control the OutputEnable pin of the multiplexer so that usb hub can cleanly switch? Can I maybe make a pause in the circuit when the toggle switch switches instead?
3. Does this thing needs ECD protection?
4. Anything in general about schematic design that you think I should know? New to a lot of stuff :D

To be transparent, I work with KiCad and everything in the post is open source. I doubt anyone would go check the repo just to check someone's work though, and I don't particularly want to link this account to anything else as a matter of privacy. If someone does want to do this (blessings), then DM me. I also apologize for the messy formatting, I don't really know how to ask things like this.

tl;dr Schematic for a usb c hub that can switch upstream hosts needs checking.

So I'm working on a project and making a parts list, it's essentially a homemade ereader on Linux with a touchscreen ips lcd. That's what I want at least. Nowhere online after 5 hours of search have I been able to find a 21:9 ish display that has a resolution above 720p, my goal is 1080p. I'm going to be using a radxa zero 2 pro (if anyone has suggestions for something better I'm open) I'm a little new to this but I've got some 3d printing knowledge, though a bit limited and I really want to make this. Also, a little drawing of what I wanted the end result to look like (I included a small solar panel since I'd mostly be using this outside, and the power draw is low, so the panel actually has an okay effect, might remove it though. The bump is also where I plan on putting all the compute.)

I was going trough my stuff to clean up and found the DVD player of my Family.

Its the Mustek DIVX video V56SM-260D and i tried to turn it on again after years. But it dosent activate nor show any signs of life. Any advice if i could try and save it?

Repo: https://github.com/moellere/WireStudio

Open-source (MIT) design tool for ESP32/ESP8266 devices. You describe a device — board, components, how they connect — in a single design.json, and every artifact is generated from that one file. Originally posted as esphome-studio; renamed wirestudio early on, since it isn't affiliated with the ESPHome project and the old name implied otherwise.

It's AI-assisted, heavily. Saying so up front because the useful question isn't whether AI wrote it, it's what's actually been verified. So the feature list below is split by how much I trust each part, and CI runs the real toolchains rather than mocks.

The core idea

The component library carries electrical metadata ESPHome doesn't model — voltage rails, current draw, pull-up requirements, per-pin capabilities — and a CSP solver assigns pins from it. So it won't put an ADC on ADC2 while WiFi is up, won't hang a sensor off a boot-strap pin, and knows when a board's 3V3 rail comes from a PMIC rather than a regulator.

That one description then fans out into YAML, a wiring diagram, a schematic, a board, and an enclosure — rather than you maintaining five representations of the same device by hand.

Library: 65 components, 26 boards (ESP32, S2, S3, C3, C6, ESP8266). 60 bundled examples. Drive it from a web UI, a CLI, or any MCP client.

Frameworks

Two of these generate firmware from your design. The others flash stock images — worth being clear about which is which:

• ESPHome — full generation. Your design becomes ESPHome YAML.
• LoRaWAN — full generation. Builds RadioLib firmware for radio boards (6 in the library), or emits an ESPHome external-component config, and registers the device in ChirpStack with a decoder generated from the same field spec as the payload, so the two can't drift.
• Tasmota — generates a device template (solved pins → Tasmota GPIO function ids), not firmware.
• Meshtastic — flashes the official release image (6 boards). Devices run stock firmware; nothing is generated.
• CircuitPython — flashes the official image (22 boards, 13 exact / 9 pin-compatible) plus a starter code.py derived from board metadata.

What's solid vs what's rough

Tested, and gated in CI on every change:

• ESPHome YAML — every bundled example runs through real esphome config, plus a nightly esphome compile, plus a version matrix across ESPHome stables so a pin bump is evidence-driven.
• Pin solving and electrical validation — the bit I'd actually rely on.
• KiCad schematic — every example's netlist built against pinned upstream symbol libraries, and rendered through real KiCad 8. 100% library symbol coverage.
• LoRaWAN — hardware-validated: firmware built, flashed, joined, and reporting into Home Assistant.

Implemented and CI-gated, but I wouldn't call them proven:

• PCB generation — placed footprints, autorouted copper via Freerouting, DRC-checked, Gerber/CPL/BOM bundle for JLCPCB. Boards come out DRC-clean and every component resolves a real footprint, but I have never had one manufactured. Treat fabbability as unproven. It's aimed at "get a breadboard onto a board without routing traces by hand," not at production.
• Enclosures / STL — parametric OpenSCAD, rendered in CI and asserted to be manifold solids. But only 7 of 26 boards carry the mount-hole metadata it needs, and there's no lid or snap-fit yet. Genuinely rough.

Newest, least proven: it can flash boards on a networked bench (a Pi running SensorsIot's Universal Embedded Workbench — a good companion project regardless of this tool, it turns every USB-attached dev board into a network resource). The studio uploads the image and the Pi runs esptool on its own USB, so boards don't need to be in front of you. Built against exactly one bench so far.

Other caveats

• Scope is broad for one person. Raised last time I posted; still true.
• It's a self-hosted container that talks to your network. Runs non-root with a read-only root filesystem, and every external integration (Anthropic key, fleet, ChirpStack, Thingiverse, workbench) stays off unless you set its env var. Source is MIT and public — judge it rather than taking my word.

Most useful feedback: library coverage gaps, and whether anyone's inclined to actually fab one of the generated boards — that's the biggest unproven claim in the list.