Reddit:Electronics

Ordered these a few weeks ago and honestly expected the usual first-spin disasters. Instead after hand-placing components and a reflow session everything came up clean on first power-on which is a rare event, so I had to share.

The board is built around an ESP32-S3 as the main controller, talking over SPI to an AD74416H (4-channel 24-bit ADC/(IV)DAC combo, honestly the heart of the whole thing) and five ADGS2414D octal SPST switches that form a 40-point MUX fabric. A DS4424 handles fine iDAC trimming of the 3 output rails, a HUSB238 negotiates USB-PD, and a PCA9535 expands the I²C-controlled GPIOs. Four e-fuses sit in the power path for output protection.

The whole point of the design is to expose all of this as an MCP server and as Python API so AI assistants or scripts can autonomously probe, drive, and debug real hardware, measure voltages and currents, sweep outputs, capture ADC waveforms without a human in the loop for each step. Since handing an AI real control over hardware is a bit nervewracking, there are hard guardrails baked into the firmware and Python API, you can define a board profile for the DUT and it physically can't exceed the defined voltage limits or drive the wrong outputs.

There's also an optional RP2040 HAT that adds a 125 MHz logic analyzer and CMSIS-DAP probe.

Surprised it worked without any bodge wires, I'm now starting to polish the tools and firmware for it.

Full schematics, firmware, and build instructions: https://github.com/lollokara/BugBuster

Anything radio never gets old to me. Somehow I missed this TA7642 radio on a chip until I came across it via surplus. I thought this might make a neat project for for an EMI sniffer. AM is great at detecting the various noise/trash thrown off by modern digital electronics. I find it a fascinating alternate world that you can explore, given the right tool.

There are various plans around the internet for projects with the TA7642, including an application example in the datasheet. So, coming up with a design is really easy.

Keep in mind that this is a prototype and there's tons of room for improvement.

On the left side of the board is the power/audio section, to the right is the RF.

I opted to exclude a tuning capacitor and go with fixed SMD capacitors on a dip switch. I know it's dirty, but for my application it's fine. Now I can switch-tune to various frequencies to get the best response to EMI and keep the overall footprint smaller.

It runs on a single AAA battery with about 1.3mA of current draw, which means it will run a very long time, some 500+ hours.

What became apparent while I was building it is how tiny you can actually make it. With custom boards and SMD components, this sucker will shrink down a ton. I'll probably revisit this idea sometime in the future.

Happy workbench Wednesday! I’ve been itching to post this since last Thursday haha.

I’m Abacus of FooseyRhode and I specialize in repair of a specific type of computer part called an ASIC Hashboard, and those PCBs are what this setup is built around servicing.

Honorable mentions at my desk that might catch some curiosity

1. The Overhead Cable Trays.

2. The rail mounted, Digital Microscope.

3. The Heatgun Glory Hole.

4. Soldering Iron suspended by pulleys.

5. The Quad-table-top fans (Fan Deck).

1 and 2.) The overhead cable trays are super helpful for the obvious, but also for storing some accessories out of the way.

My primary heatgun for example. With it up there, wrist strain from the heavy heatgun gun hose is practically eliminated.

I also mounted my PC and digital microscope up there. Microscope benefits because table vibrations are gone, and computer is just there for cable management.

3.) See image 3. Looks crazy but it’s very necessary for my work. The PCB I work on are typically single layer PCB secured to a giant aluminum plate. A lone heatgun is not capable of achieving solder flow, and hot plates are extremely impractical for PCB like this. Thus, I apply heat from above, and below.

Getting the damn thing mounted safely was the hardest part. I used a pneumatic vesa monitor mount, but backwards. I hammered the vesa mount into shape and secured it to a desk beam. Then I secured the opposite end of the mount to the heatgun.

4.) The pulleys just keep the soldering iron cable out of my way. Honestly, I’m just resolving a minor inconvenience for myself with this.

5.) My 3D printed Fan Deck! It’s four 120mm fans powered through a potentiometer so I can control the speed. It’s used primarily when I am diagnosing a board.

The boards I work on use around 40-90 amps when operating, but for diagnostic, require only 10-20 amps to test properly. Point being, they heat up very rapidly, and heat affects my diagnostic. The Fan Deck is a means to cool boards down while simultaneously injecting power into them.

And wrote a blog post about it https://atomicsandwich.com/blog/breathing_apparatus

This little project is the mainboard for a noise activated roller-blind and the circuit incorporates 31 through-hole components and 20 SMD components.

Now time to begin testing!

PS: Please excuse the soldering

I have to brag, but first I have to tell on myself a little bit. You should really read the datasheet more thoroughly than I did. On the DRV8304 gate driver in 3PWM mode, the INLx pins need to be connected and pulled high for the phases to be turned on. If the pins are left unconnected or pulled low, the driver will put the phases into coast mode (all MOSFETs disabled). Also DVDD is an output pin, so don't connect it to 3V3.

In this image you can see where I cut the trace from 3v3 to DVDD (between the C and the 5 of the C5 reference). Happily, I was able to scrape some soldermask off the trace before the cut, and then bodged some 34AWG magnet wire onto it and connected it to the INL pins to pull them high. After this (and some fixes to a couple of failed joints on other pins) the device was showing correct outputs on the phases.

This is the first time I've ever bodged a PCB so I'm really excited I was able to get it working. This is just a test board for a more complete project I'm going to do down the line, so i'm not too worried about the longevity of this fix. But it's good to have this skill in the toolkit.

Ordered a SOT323 diode instead of a SOD323, worked out in the end. Just had to make sure not to let pin 2 touch the exposed ground plane

I made this little piano using an ATtiny85 and a some push buttons. All 12 keys are read through a single ADC pin using a resistor-ladder voltage divider. Each button taps a different point in the chain, so the voltage tells the chip which key is down. Functional but quite limited as only one key really works at a time.

This was my first project to learn the ATtiny85 and I'm happy with how it turned out. Sounds pretty rough though.

Tried to use it to light some LED’s though I think the circuit expects a battery voltage to use as feedback as it has very low output current otherwise. Short circuit current was 300mA

Current setup 😅

ESP32 + RFID + SDR + random modules

Not sure if this will fully work yet…

But it’s getting interesting 👀

Any ideas what I should add next?

There must be a T48 UV erasing addon with the EPROM blank check.

270-280nm 800mW diode.

I have been designing PCBs to carry a small microcontroller, an RS485 transceiver, an LED and the associated balance of plant required to make lights for my ROV. Space is at a premium, so track sizes are being chosen to minimise real estate used.

KiCad has a netclasses setup page that uses IPC 2221 requirements and PCBway capabilities. I have come up with a sensible set of pre-defined values

https://philipmcgaw.com/kicad-traces-net-classes/

It is 3-rd LCD panel in a month with the same issue, backlight stopped working, there was one resistor still measuring 270 Ohm so we know what it should be, all others are open circuit or in xx MOhm range. No signs of corrosion or overheating anywhere, just crappy components, never have seen this issue. It is planned obsolence or bad combination of materials in resistor. Share your experience with similar cases.

Its a jdm 030 usb charge board but which one of these is the fuse ( that i should replace ) after a short circuit. And is it worth replacing it ?

We used to have a wired door bell button as a garage door opener near the back door inside the house. The wiring got damaged in an area new wiring couldn’t be rerouted during renovation.

Came up with this solution - took a garage door opener apart - connected wires to a decora style momentary switch and soldered other end to the pads for the buttons on pcb.

Added a whip antenna to over come shielding of electrical box and drywall. To maintain the 9 inch whip antenna, drilled a small hole in electrical box and fed it into wall.

Works perfectly.

I used to use PCBWAY years back for a long time, doing over 100 high value jobs with them and they were good. I never had any real complaints. I moved over to JLCPCB due to the majorly lower cost a few years ago and to be honest I also couldn't complain with their service for a good amount of time.

I have been using them for prototyping for about 3 years with the occasional small batch run up to 200 pieces of fairly basic stuff like ESP32 etc. Recently I have started a small business that uses a reasonbly complex setup of USB at 5Gb/s and MIPI CSI at 2Gb/s with the corresponding high value parts of the image sensor and CYUSB CX3 transceiver. I have now made 4 batches.

Batch 1 of 5 pieces:
- Issues with the TMC2209, no communication and occasional explosions for no apparent reason. They would just lock up and sink full current through windings thus killing themselves.

Batch 2 of 5 pieces:
- No issues

Batch 3 of 25 pieces:
- The CYUSB chip would just NOT boot, it would sit in a reset state and nothing I could do would change that. Small changes had been applied to the PCBs over the batches but the schematic and layout remainded IDENTICAL for the CYUSB part of the design. This delayed by project by 3 months. Infineon were very helpful and spent a really good amount of time helping to debug the design comparing the new design from schematic to gerbers to xrays, they deemed the design was identical from their perspective and put it down to a PCB fabrication fault. This affected all 25 PCBs.

Batch 4 of 5 pieces:
- I decided to make another batch of boards while supplying my own CYUSB chips - they work no problem now.
- TMC2209 is blowing up again, replacing with parts from Digikey solve the problem 100%.
- I have an STM32 for house keeping on the board. Never touched this part of the design from the first batch, it now runs but I cannot maintain SWD debug without disconnect and now unable to program it via the bootloader...

Every time I order a batch I get a different outcome. No question JLCPCB uses fake parts intentionally or unintentionally. The outcome is the same. For me I'm going to be moving to a alternative Chinese supplier with free issued parts.