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.

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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.

I had a lego pack sitting around that I has sorta messed up years ago for somthing, desided see if I could jam a 9v to 5v converter in it, to say the least I sorta went way smaller than I actually needed, in theory it can take 1.5 amps, I wont get even close to that using it, to help with the heat it has some copper sheet attached the sits against the AA to help spread heat from it, parts used are two 10UF caps, ceramic 0.47UF on 9v side and a ceramic 0.1UF on the 5v side, the souldering is a little rough, but this is the smallest thing Ive ever made by far, Im sure it would be better if I did it a few times.

i had one mechanical keyboard after getting bored i tried to reverse engineer it but i couldn't send any usb data or i could not see much on the terminal when i tried to see if it listens to the data and after opening i saw that it only takes +5v and gnd plus the processor something like BYK.. was a hard coded chip that doesnt listen notes i was newbie to hardware and really scared to try anything. so i gave up but seeing my brother have a kreo rgb keyboard it gave me some boost to open it up and i learned so much and burnt my hand while trying to solder.

heck i even burnt the solder iron's wire itself (sniff sniff whats that smell).

so the plane was that i would use a mcu as esp 32 or pico that listen to my command and can do anything that i want .

first month really ....

i bought a mulitmeter and did the traces of all the rows and col sicne there was no pcb and other design files there i didnt know how keyboard matrix works at all i went rhough whole thing.. after getting all the traces and nothing them i was really soul scattered by the fact how this whole thing worked but then i got to know this was a common thing everyone knew this.

after this i took pico as the main mcu why...

1. it was small
2. it has higher clock speed.
3. it was one sale since the esp was on boom and the price of pico was dropped
4. it has more computer power that i needed for Fourier transform for disco light that i wanted for the custom rgbs i would put there

quickly after that i ran into a problem of less gpio also

after that i took a longer time to solder since i was learning and it was very scarry to solder on the pcb but as i did i grew more confident .. after burning my finger prints.

i bought a io expander because of 6 rows and 17 cols it got burnt and again tried that was jittering the one signal was affecting other signal. so i gave up 3-4 cols and went for the gpio full on.

The RGBs... Hardest

the rgb i had to cut each rgb strip stick them all on each keys then use the single core wired without the cover and solder each joints aroung 300 small pieces of them total 600 joints appx and it was tough because heating one end would make other end heat up also.

but since i cascaded 100 of them the voltage kept decreasing and it was 0.5v at the end so i just provided supply from both of rows and it worked and there was no deeming and jitters.

thats it... if u want to know about the logic behind it then u can ask me i will add it most of things and testing and all the stuff is in the video

TI sells a light-sensing IC (OPT3001). Since it needs to detect light, the package is clear. I think this is very cool. A couple pictures have a quarter for scale.

Really baffling decision, my last order from them was only a few months ago. Apparently Linux is no longer a "standard" operating system!