These two boards are designed to work together. The new board takes 12V input and outputs 4.15V. Smart folks might be able to guess what this is for. I’ll keep it a secret for now and reveal it in the next post :)

The reason I started this project is that my final load can draw up to 20W at full power, which translates to just under 5A at 4.15V.

I tried a few TI solutions, but while working on the PCB layout, I came across an interesting module from the ZXDN10 series. It doesn't seem to be available for individual purchase, but I managed to get some stock through a business-to-business channel.

Unfortunately, there’s no public documentation available for this module. Based on the PCB silkscreen markings, it appears to use a TPS40192-based synchronous, non-isolated buck converter design.

By tracing the visible PCB connections and checking them with a multimeter, I was able to reverse-engineer what I believe is the pinout. Pretty exciting!

The module is supposedly rated for up to 10A of continuous output current, but I have my doubts about whether it can actually sustain that much under real-world conditions. I added a heatsink to the PCB and tested it myself. So far, it can reliably sustain 6A continuously, with efficiency staying around 94%.

I also added an ideal diode circuit on the output side of the module to prevent unwanted reverse current from flowing back into the converter.

More to come in the next post! :)

I'm building an STM32F103C8T6 development board and would appreciate feedback on my layout and schematic.

Key components:

• MCU: STM32F103C8T6
• LDO: LDL1117S33R
• HSE Crystal: ABM3-8.000MHZ-D2Y-T
• LSE Crystal: ABS07-120-32.768KHZ-T
• USB ESD protection: USBLC6-2SC6

Crystal component values were calculated using equations from ST's AN2867 with parameters from the respective datasheets.

I'm using 0805 passives for hand soldering, with 0603 for sensitive traces (crystals, USB data lines). ERC and DRC both pass with zero errors.

Any feedback on the design or links to best practices would be appreciated, Thanks!

Developed a 5V-3.3V Voltage Regulator Breakout Board, requesting for y'all suggestions and opinions. Thank you 😄

This circuit can generate PWM pulses from 1Hz to 1 MHz with a duty cycle from 0% to 100%. You can also switch the PWM logic level between 5V/3.3V.

The schematic and PCB were created using Altium Develop.

The firmware was developed using the MounRiver Studio IDE (MCU: CH32V003J4).

More Details: www.youtube.com/watch?v=-Cdu3wlyYDU

Hey guys,

have been wanting to design boards a lot more lately, but one of my biggest “gripes” with software is getting parts from DigiKey / Mouser into my schematic / layout.

Now, OrCad / Cadence has a great system with a built in manager / component search with SamacSys, UltraLib, SnapMagic, etc.

Altium has Octopart (which IMO blows) ( At least in comparison with UltraLib and SnapMagic ).

Now, KiCad has been speaking to me a LOT recently. I want to build boards on my laptop, because it’s portable, and I’m at school a lot. It’s just the parts.

I would really like to hear some work flows for getting these parts.

Like, I really love that in OrCAD (which we use at work (but I don’t want to pay for personally)) you can put in the part number and it will place / download / and organize everything for you. SAVES SO MUCH TIME in the workflow.

So, in KiCAD, is there something similar? Of course, you’ll have to be on DigiKey / Mouser anyways to find the parts, so anyway to just, find the part needed, and then click of a button, it downloads symbol, footprint, and model? Pretty much plug n play?

I would love to hear everyone’s thoughts on both
- The workflow for getting parts
- your thoughts on the toughest aspects of a workflow for PCB layout / design.

Hi everyone!

I'm designing an ESP-controlled relay driver using an optocoupler and a transistor, and I have a question about the pull-down resistor.

In the reference circuit I'm planning to attach, R6 is the resistor right after the optocoupler, while R4 is located before the transistor.

Is a pull-down resistor needed in this part of the circuit? If so, where should it be placed — on the optocoupler side (R6) of the series resistor (R3), or on the transistor side (R4)?

I'd appreciate any advice on the correct placement and whether a pull-down resistor is necessary at all.

Thanks in advance!

Hi everyone! I’m working on a custom multi-layer PCB for a powerbank featuring an STM32G071CBT6 MCU and a BQ25792 buck-boost charger/PMIC. Before sending it to fabrication (targeting JLCPCB), I would love to get your feedback on the layout, power distribution, and overall routing practices.

Board Layers:

1. Signal top traces
2. GND (no traces)
3. 3.3V supply and signal traces
4. Signal bottom traces

The battery pack consists of a 4S2P configuration using INR21700 50E cells (4 series, 2 parallel). It provides a capacity of 20,000 mAh with a voltage range of 16.8V max, 14.8V nominal, and 12V min. While the max discharge current from the battery pack is 20A(10A for one cell), the system software restricts it to a 3A max limit.

The BMS features individual cell voltage monitoring and temperature monitoring per cell group via ADC, along with passive cell balancing using high-side P-MOSFET switching with a 75mA balancing current.

The BQ25792 serves as the main buck-boost power management IC. It supports a max charging/output configuration of 20V and 3A (60W), as well as typical fast-charging profiles like 9V/3A (27W) or 5V/3A, optimized for modern electronics including Apple devices like iPhones and MacBooks.

The STM32G071CBT6 acts as the main MCU running on 3.3V. It handles USB-PD protocol and power negotiation with connected devices, reads ADC data for cell voltages, current, and thermistors, and controls the cell balancing logic.

Additionally, the PCB provides a display interface and a single switch button for user interaction.

Please tell me if there is a chance it will work.

Hello, thank you for taking the time to read my post.

I completed my first-ever board recently, and while testing it and trying to connect the ESP to the IDE, I realized that it wasn't even turning on. I looked around and realized I'm only getting 2.7 V instead of the 3–3.6 V I need from the switching regulator.

I'm using an ISL854102, and I have two theories, but I'm not sure. The most plausible one, in my opinion, is that the distance between the chip and the voltage divider (R6-R7) is too large, so it ends up regulating the output to 2.7 V instead of the 3.3 V I want.

I used this formula to calculate the correct values: VOUT = 0.6 × (1 + 100/22.1) = 3.32 V

I'm thinking I could fix the issue by changing the resistor values so that the regulator reads the correct voltage and provides the expected output.

My second theory is that it's some kind of brownout loop, but I don't know how to fix it.

I'm using a bench power supply for testing, and I should also mention that the power indicator LED never flashes at any point while the board was getting power.

I've attached a picture of the board in KiCad, the schematic, a 3D model of the board, the relevant section of the ISL854102 datasheet showing the circuit, and a picture of the schematic for an example module I found from Pololu.

Hi guys. For reference, I do not know anything about PCBs, im just a car guy trying to install an aftermarket keyless lock on my really old car. With that being said, I spent the past 2 weeks pulling my hair out trying to figure out why my door locks fail to properly lock/unlock when I press the key. Turns out, the reason is that my old car uses a pneumatic system, and i didnt set the control module to have a longer pulse so the system can build vacuum. Great, so I take apart the module, and I lose my hair another 3 hours trying to figure out what the damn instruction manual means, but I came to the conclusion that I need to DIY this and its not a simple button to change the pulse time. But now I am at this next headache where the silkscreen is complete dog and the user manual is unclear. Ive located JP1 and JP2 as what I need, but where do those lines go? Where do I bridge the wire? Your help would be greatly appreciated

Tldr: which two points do i solder a jumper to so I can make my vacuum actuator go for 4.5 sec as per instructions

I use Hyperlynx for SI and PI simulation.

If anyone has a PCB design they'd like to analyse, I'd be happy to explore it as a learning exercise and share my findings. I'm particularly interested in learning from real-world designs.

Just looking for practical experience and knowledge sharing.

Feel free to comment if you're interested!

Any advice?

I am working on this PCB for an glider plane. The goal is to have an esp32 with usbc boot and reset button and 2 sg90 servos running on 2 AA batterys. I thought it would be simple at first but yeah it wasn’t . Therefore I think there must be a mistake can anyone spot it before I start making traces. Thanks for taking your time I really appreciate it.

Hi guys, so these boards are from a taillight and I’m trying to learn how to fix it.

I’ve not removed it yet from my own but I have some experience doing that as I replace lenses/housing etc on headlights so there’s no issue get the board out. The issue I’m having is identifying how to find the problem.

The issue with the tail light is the brake lamp when on the car (which is the inner ring of LEDs on the board) flashes once then turns off. What steps you think I should take to identify the issue?

I am studying Electrical engineering and I am in 5th semester I have recently made this 3W Led driver circuit. Is it worth according to 5th semester ?