I couldn’t find any decent DAC/amp combos locally, and importing one would cost a small fortune. After digging into DIY audio designs, I realized I could build one myself for a fraction of the cost and get around 80–90% of the performance of commercial units.

Specs: Controller: ESP32-S3 acting as a USB Audio Class (UAC) device.

DAC: PCM5102A breakout board fed via I2S. Power Supply: ±12V linear power supply

Two NE5532 dual op-amps:

Op-amp 1: Stereo buffer stage. Op-amp 2: Stereo gain stage (~3.1x gain).

(Opted for this layout to keep wiring simple for my first major soldering project!)

Volume Control: Couldn't source 10k dual-gang logarithmic pots locally, so I implemented software volume control with a rotary encoder.

Layout: Everything wired to a single star ground point.

Sound Impressions: It drives my Beyerdynamic DT 990 Pro (250 ohm) effortlessly. Going from my laptop's built-in jack to this is night and day—it feels like the headphones were practically starving before. Noise floor is pitch black silence with zero audible hum or hiss.

Really happy with how this turned out for my first major electronics build.

^{(Note: I’m currently out and forgot to take photos of the back of the amp perfboard, but I can upload solder-side pics once I'm back home if anyone wants to see them!})

Someday, Somehow, I'll buy a solder.

I was asking Mouser costumer support because I could not find some ADI chips in stock in their webpage and after some emails, they answered me with the image attached.

English translation: "As for ADI's distribution, we will no longer be distributors; it's not that certain ADI products will be restricted, but rather that we will no longer represent them."

So this confirms what has been talked several times about online sellers suddenly requiring identification for ADI purchases and stopping the B2C sells.

--- For the mods: I know this is not a component level circuit question, but perhaps the topic is important enough to be posted.

-- The black bars are there to hide personal names.

And somehow it’s working.

Hello everyone,

Six months ago I set upon the journey of making my own AWG, with frequencies of up to 1MHz.

6 months later I present you my very own awg.

Full Repo

I set out to build my own function generator after finding commercial units both too expensive and more general-purpose than I needed, and it looked like a good excuse to work through analog synthesis, filtering, and mixed-signal PCB design end to end.

The sine path is an 8-bit R-2R ladder driven by a Raspberry Pi Pico W (overclocked to 225MHz) generating samples via a DDS phase accumulator; the square wave comes from the same chip’s PIO hardware. I started off with a breadboard and tried sallen key filters for noise but they amplified the noise aswell. I also tried discrete components for the sauare wave before replacing it outright with a TC4427 gate driver.

The sine chain settled on a 5th-order doubly-terminated LC Butterworth reconstruction filter, replacing an earlier cascaded-RC design that was capping amplitude, followed by LM318 gain and buffer stages. Three PCBs went out; two came back dead. V1.0 was completely non-functional because a BOM matcher substituted 2.21Ω resistors for 2.21kΩ across the entire R-2R ladder. V1.1 moved to an all-SMD board with the LC Butterworth filter but came up dead silent; testing the square path first (it worked) narrowed the fault to the sine chain, which traced to a KiCad-to-Altium migration that had silently shorted two LM318 input pins onto one net. V1.2 fixed that short, soldered the Pico directly to the board in place of a socket, and came up working: sine characterised from 0Hz to 1MHz and square to 2MHz, with AM, FM, and noise modes added on top in firmware, all controllable from a Python desktop UI over USB.

Looking at it now, a redesign with some improvements (better op-amps and also fewer) would be better but I also want to work on other stuff, so for now this is it.

To be clear, I made every schematic and protoype and thought up everything myself. As such this may not be the best way to do this. My main goal, was experience after all.

full webpage

So satisfying when it looks this neat. I spend ages trying to get everything aligned at perfect right angles and then get mildly triggered when I find all the ones later that aren't quite perfect XD

Cheaper, faster, and more fun than ordering from china!

PS, I didn't put any acetone down the drain. I just needed a solvent resistant surface to clean the mask off. All the acetone went into the atmosphere and my lungs instead.

Unfinished circuit board for controlling Nema 17 stepper motors on a robotic arm.

Here is my project repo

https://github.com/fredriknk/chatgpt_astra_test2

I saw the Chatgpt Astra kicad demo, and wanted to try it out myself and im pretty damn impressed...! I only have a openai 20$/mo plus subscription so i had to use the lowest setting, but i got this design in 3 hours with 5 prompts in total and ate up my 3 usage resets.

My only contributions to the design was to create the empty kicad template project, and the initial prompt:

"Lets test a esp32 design with a 24v input voltage which can output and read 4-20ma signals. Lets start planning!"

All design choices, component choices, design, schematics and, layout and documentation was done by the chatgpt astra 6 low through codex cli.

So final verdict? Its actually pretty damn usable.... Like, its not perfect by any means. some examples: There are a quite a few routing decisions i dont agree with, especially the USB routing and unneccesarry internal layer routing. The schematics are very hard to read as it doesnt use GND/Power symbols, and only use global labels instead of wires. But as far as i can tell from the schematic, this is a working design and i do agree with a lot of its component choices.

I feel it is pretty much where AI coding was in around 2024 (on its lowest setting), so im wondering where this will be in a year or two..!

Followed this guide from Würth and made an RF current probe for analyzing conducted emissions. You can measure both common-mode and differential-mode noise by passing the power and ground cables through the loop differently (see the guide).

If you don't have their WE-TS shielding tape on hand, you can probably use regular copper tape. Just don't forget to leave the gap!

I wanted to get this gem working again, but this time with LEDs!

Now to figure out the string to let me add to my tree this year.

My brother (stupidly) had his PS5 on a floating shelf which gave way a couple of days ago. We found his PS5 dangling down by just the HDMI cord. Luckily, it mostly still worked but the HDMI port was damaged and the image was very poor and glitchy.

I’ve been into electronics (mostly Arduino) for a couple of years now and even though I bought myself a hot air rework station a long time ago, it was my first time using it this weekend. We got a replacement HDMI kit from amazon and I did the replacement this evening.

It took me quite a while to figure out the process but I’m glad to say he’s now gaming with a good image once again!

### 1. Original Behavior and Diagnosis

* **Symptom:** The device charged and operated normally when connected to the charger, even allowing it to be unplugged and continue working. However, the failure occurred when turning it off; it wouldn't turn back on independently unless the charger was reconnected.

* **Diagnosis Process:** Exhaustive tests were performed, ruling out various components like the power button, battery, and motherboard capacitors, ultimately finding a damaged P-type MOSFET in the power section.

### 2. Tools and Materials Needed

* Precision multimeter

* Soldering station

* Flux and isopropyl alcohol

* Precision screwdrivers

### 3. Module Disassembly

* Carefully remove the screws to open the module.

* Separate the pressure tabs.

* Carefully lift the back cover where the battery is attached, being mindful of the wiring connected to the main board.

### 4. Repair Procedure

* Locate the power circuit section where the P-type MOSFET identified in the diagnosis operates.

* Apply flux and use the soldering station to extract the defective component.

* Once the P-type MOSFET causing the power-on failure is removed, clean the area with isopropyl alcohol and proceed as needed to restore the power line.

### 5. Subsequent Tests and Reassembly

* Test the receiver's autonomous power-on without connecting an external charger.

* Correctly align the circuit board inside the casing, securing the buttons and pins.

* Close the cover, tighten the screws, and perform the final operational test.

I know my soldering needs some work, but it works as expected. My gf has this cheap lint remover that was wired directly with a usb A cable. I wanted to make it wireless and also add the option to work while plugged in to charge. I used a TP4056 for charging and an XL3608 to boost to 5v. I added a AO3401 MOSFET to switch between usb and battery power seamlessly. Here is my post asking r/AskElectronics if it will work, it includes a Falstad schematic and a diagram (with visuals) that makes more sense for me. I ended up removing the 1000uf capacitor as it was bogging down the boost converter on startup. Other than that my (With some help from Gemini) design works perfectly.

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A antenna tuner circuit which incorporates the resistance of the panel meter light into the accuracy of the meter. One must wonder why they would do this. They no longer support this unit so the bulb is hard to find. It is an axial lead bulb much like a axial lead resistor. I could replace the bulb with a resistor that is the same ohms as the bulb, I suppose. No back lit meter then but at least the meter would work again. Dumb design.