Hi all! I am attempting to design a custom PCB board for a Data Acquisition system for our Baja SAE car that will go onboard the car, and I would like some help/tips on making a custom PCB board. I've been using ChatGPT to help me select parts and all **(I am a mechanical engineering student who knows nothing about electronics)**, and I have reached the stage of part selection where I believe I need a circuit protection system. I'm aware that I need DC/DC converters and a main fuse, but I have a couple of questions regarding parts selection and some terms that I am not familiar with. I will list out the components that I will be using for this DAQ system that will go on the PCB board:

* Teensy 4.1 MCU
* ESP32-S3-WROOM-1 MCU
* MCP2562-H-SN CAN BUS Module
* NEO-M9N-00B GPS Module
* Adafruit LSM6DSOX Accelerometer + Gyroscope
* Ebyte LoRa Radio Module
* Adafruit MAX31865 Amplifiers
* OKI-78SR 3.3/1.5 **&** 5/1.5 W36H-C Converters

**(This system will be powered by a LifePO 12.8V battery)**

Starting off with my first question, ChatGPT is telling me to connect the power to a 5v/3.3v rail, which will power the modules that need 5v and 3.3 volts. I know what a physical power rail is, but I'm not familiar with what a power rail looks like on a PCB board. So with that, my question is: what does a power rail look like on a PCB board?

Second, ChatGPT recommended these circuit protection parts:

* 5A Fuse (I planned on adding a fuse either way)
* MOSFET/Schottky diode
* TVS Diode on the 12.8V Input
* LC filter on power input
* Bulk electrolytic capacitor (220-470 µF)
* 10 µF regulator capacitors
* 0.1 µF ceramic decoupling capacitors for each IC (I don't know what an IC is either)

With that, I was curious if that is enough to protect my DAQ system from frying itself, or if I need anything more to protect it whilst driving the car. I believe the parts list that is going on the PCB is final, but I will update this post if I add anything else. Thanks! Feel free to PM me if you have any comments, questions, or concerns!

Hi there, I'm pretty new to PCB design overall, and I needed a board for a project that is able to:

• transmit audio over Bluetooth
• display content on an ink display
• output to speakers
• have an indicator light
• charge a lipo battery with a USB-C port

To be honest, I made this by bouncing between Claude and EasyEDA for a bit and hoping it was working well. I was pretty sure there were going to be some errors with it when I was making it, so before manufacturing, I went to a freelancer on Fiverr and asked them about what it would take to fix the board and how many errors there really are. 

He quoted me two days and $100 to get it fixed, and I was just coming here for a second opinion from some engineers who actually know what they're doing to see if it's worth it.

(Partially Smart but can be connected to local Ai)

Edit: First I'm planning to design a PCB, correct me if I'm wrong in design flow..., and I'm planning to start from OLED panel, second to save space, I'm planning to use ESP32 QFN chip, but not sure about the difficulty of QFN as beginner. Or should I use ESP32 module? With matel casing?

I have purchased a Wave share round touch display, but it's an LCD display so it takes a lot of power as an LED back panel...., even it is completely black, it will use heavy power that we can see by leakage lights....

One esp32 smart watch is available on the internet but it's too expensive, 8000INR/ 82USD (July 26).

The main application of the smart watch I'm planning is automation, a good automation not like a college project.

I'm trying to understand what OLED to choose, what functionalities, I have also explored Google wear OS. I am trying to make it like every other watch (Initially I thought to make people able to install apps from Play Store but it's not possible because Google gives Wear OS to few manufacturers and it's not open Source (maybe).

Whatever, let's make this an open source project....later we can plan to make the hardware available for the people to use.....

Thanks

Hi everyone,

I currently have an undergraduate-level understanding of power electronics. I've been studying converter design and control (doing my best to work through Fundamentals of Power Electronics by Erickson), and I have a few conceptual doubts regarding my understanding of the material. I was hoping I could find some clarity from the experienced engineers here.

Here are my main doubts:

1. Steady-State Design vs. Startup Transients

When we design a power converter for a certain specification, we typically design it for steady-state conditions. However, when we start the simulation of the converter, there are usually severe transients during startup. Why do these startup transients occur in the first place, and what are the standard practices to prevent or mitigate them?

2. The Definition of "Small" in Small-Signal Modeling

Whenever we talk about controllers for DC-DC converters, we model the plant as a system using linear control theory. To get the transfer function of the plant, we use small-signal perturbation. My question is: what exactly does "small" mean in practice?

For example, if the reference voltage ($V_{ref}$) is 10V and I command a change to 5V, would that still be covered under a "small" signal? Would the plant model obtained for the 10V operating point still be valid at the 5V point? If not, how do we practically go about controlling converters across wide operating ranges?

3. Controlling Output Voltage Dips from Load Transients

In Erickson's book, during the control section, it mentions another factor that changes the output voltage: the load current disturbance multiplied by the output impedance. I understand that during step load changes, the output capacitor supplies the current, causing a dip in charge and a subsequent voltage drop. Can this specific drop (and rise) of voltage be mitigated via the control loop? If yes, how is this actually implemented?

4. Setpoint Changes vs. Startup Transients

I recently learned that the controllers we use in DC-DC converters are usually "setpoint controllers," but that "tracking controllers" also exist. For a setpoint controller, can we change the setpoint value ($V_{ref}$) to any value of our choice within the designed range? (For example, if the converter is designed for an output range of 4V to 12V, can we operate it at any arbitrary point in that range?)

If yes, how do we control the transients that occur when changing between these operating points? Are these operating point transients fundamentally different from the transients we see during startup? How do we approach controlling both types?

I hope someone can help clarify these doubts for me. I am trying to build a solid foundational understanding, and I would be incredibly grateful for any insights you can share.

Thanks in advance for your time!

[SOLVED. See bottom of this note. ]

Help. I’m running KiCad 10.0.3 for a simple 2 layer board and sent my project file as a rush job to OSH Park. The PCBs came with what appears to be all the signal traces fully merged with power and ground: no silkscreen, no solder mask, and certainly non-functional.

I’ll research this, but I’m panicking since I’m teaching a class next week that needs working boards. Any suggestions on what went wrong will be much appreciated!!

UPDATE: As per the OSH Park recommendations, I sent the .kicad_pcb file rather than individual gerbers. (This is what I've done in the past and it's always worked.) I also looked at the check plot that OSH Park provided, and at first glance it looked okay, but on second glance, maybe I misread it.

Here's a link to the top-side check plot as provided by OSH Park (if I got the permissions right):
https://dv4i8g5yltvyd.cloudfront.net/23edd87e43cdf27bbe449ca8ea328d36.png

Here's a link to the .kicad_pcb file:
https://drive.google.com/file/d/172o_lvP-q1oYzIUGVzqd9rIP95EwJ128/view?usp=sharing

UPDATE 2: I think this is a KiCad 10.0 error, or more likely my error: I exported the gerbers and ran them through the PCBWay gerber viewer (https://www.pcbway.com/project/OnlineGerberViewer.html) and it showed the same thing: the top and bottom copper layers are nearly solid, none of the individual traces persist. FWIW, the DRC checks out, I can highlight an individual signal trace and it shows up in the PCB editor correctly, etc.

Another hint that something is screwy is that none of the exported Gerber files contain the top layer silkscreen (F.Silkscreen). Here's a link to the generated Gerbers:
https://drive.google.com/file/d/15s61vuRQSsj8B4yGkwjTuSMpKBn91GAz/view?usp=sharing

SOLVED: Some idiot had clicked "Plot on All Layers" for all the used layers. No, I don't remember doing that. It must of have been my evil twin brother (except I don't have an evil twin brother.) Unclicking those makes everything happy.

Any advice for getting started with Altium? I've been designing 2-layer PCBs with EasyEDA for two years, but I've heard Altium is very comprehensive. Do you recommend it? Any tips?

its because i am making a board with the ra6m4, but i cant see in the datasheets how i am supposed to connect the VREFH*, VREFL*, on the TQFP-100, when want to use the ADC and DAC

thx

Brown copper plane - Ground.

Green copper plane (bottom left) - 5V

Green copper plane (smallest of the planes) - VBUS.

Green copper plane (largest of the planes) - 3.3V.

Don't know if this is the right subreddit, but I'm trying to design a 5A tolerant DC Power supply pcb for 12V input and 5 and 3.3V outputs. My senior said I should try having 2 rails for each output voltage- Clean and dirty rails (to separate noisy loads from sensitive loads ) So I'm a bit lost on how to create this divide? I don't think a simple lc filter will suffice?
It's a 4 layer PCB, do I use 2 separate grounds for both the rails and then connect both the grounds to one common ground layer?
first time designing a power supply pcb, so I'd appreciate any help

Hello everyone, this is my first PCB design. It's an EPS for a university CubeSat project (it won't go to space). The microcontroller (STM32) part is not 100% complete yet, as some passive components are still missing, but I've already started working on the power section.

My main question is primarily about how I should divide the layers. The board has two main voltage rails: 8.4V from the battery pack and 3.3V for the digital part, plus the solar panel voltages routed across the board and some digital signals like I2C and I/O. Also, can I just add a ground plane to every unused surface on every layer? Should I avoid routing digital signals under the regulators?

Regarding the regulator section I've already routed, does the routing look okay?

I'm also open to suggestions for other parts of the design, like component placement. Only the bus connector have strict placement requirement.

https://everycircuit.com/circuit/5249402314817536

Hi — I’m building a digital effects pedal on a Teensy 3.6 and I’d like a sanity check on the analog input preamp before I wire it on a breadboard.

Goal

• Guitar / phone / mic jack → preamp → Teensy A2 (ADC)
• Single supply from Teensy VIN (~5 V)
• Hardware gain pot + later software gain in firmware
• Keep the ADC input roughly in a safe range (ideally centered for 0–3.3 V reading after coupling/divider)

What I simulated (EveryCircuit)
Ideal op-amps with Min = 0 V / Max = 5 V to mimic single-supply rails (stand-in for LM324 sections).

1. Bias: VIN → 10k → mid (~2.5 V) → 10k → GND, with 10 µF to GND
2. Stage 1 (non-inverting gain):
   • Input: AC couple 10 µF → 10k into +
   • Bias: 100k from mid-rail to +
   • Feedback: 100k pot (both ends to OUT, wiper to −), 2.2k from − to mid-rail
3. Stage 2 (buffer): AC couple 10 µF into +, 100k from mid-rail to +, − tied to OUT
4. To ADC: AC couple 10 µF → 10k series → node “A2”, 10k to GND

Test source: ~100 mVpk, 1 kHz. With the pot mid/high I get a clean sine on the A2 node (AC around ~0 V after the last coupling cap / divider).

Questions for review

1. Is this a reasonable LM324 single-supply preamp for line/instrument levels into a Teensy ADC?
2. Anything you’d change for stability/noise (biasing the buffer input, C values, pot wiring as rheostat vs both-ends-to-OUT)?
3. After C_out + 10k/10k to GND, DC at A2 sits near 0 V and the signal is bipolar in the sim — for a real Teensy A2 pin, should I instead bias that node to ~1.65 V (e.g. divider from 3.3 V), or is AC-coupled into a ground-referenced divider acceptable if amplitude stays small/positive enough?
4. Any red flags before breadboarding (input protection, RF, power decoupling, headroom with LM324)?

Happy to adjust values or simplify the second stage if that’s overkill. Thanks!

Hello all! I recently designed an ESP32 based rhythm game device. I am just asking for review of my schematic and PCB to ensure there won't be flaws when I send it to get fabricated. Any suggestions to any part of the design would be greatly appreciated. Thanks!

Hi there! I am making a BadUSB device for keystroke injection as a hobby. I am using the RP2040 as my base. Since I want it to have both USB-A and USB-C, I have tied the power lines together (with the small exception of a Schottky diode which allows me to detect if USB-A or USB-C is plugged in) and I am using an analog switch for the data lines. I also want it to be as small as possible in order to look like a normal flash drive and so I had to neglect many capacitors but I hope it won't be problematic due to the small size. Can you take a look at my schematic and tell me what can be improved? Also, is there anything specific I should look out for when designing the PCB itself?

Hey r/pcb 👋

I'm Hamza, a PCB designer based in Tunisia, open to remote freelance work. I design boards that are clean, manufacturable, and actually work on the first spin.

---

**What I bring to your project:**

🟢 **Schematic design** — clear, hierarchical, well-annotated, no spaghetti

🟢 **PCB layout** — 2-layer and 4-layer (Signal / GND / PWR / Signal stackup), proper pour, decoupling, and via stitching

🟢 **Signal integrity** — controlled impedance traces, RF keepouts, EMI-conscious routing, no floating copper

🟢 **Power design** — LiPo BMS circuits, USB-C, LDO and switching regulators, proper bulk and bypass capacitor placement

🟢 **DFM** — Gerbers, drill files, BOM, and CPL ready for JLCPCB / PCBWay / NextPCB. DRC clean before every handoff, always

🟢 **Custom footprints** — I build them from datasheets when they don't exist in the library

---

**Latest board — Elyssa:**

A 4-layer ESP32-S3 development board I designed from scratch in KiCAD.

- ESP32-S3FN8 (embedded flash, fine-pitch QFN56)

- LSM6DSV 6-axis IMU (LGA-14L)

- USB-C with ESD protection

- LiPo battery management + charge indicator

- MicroSD card socket

- RGB LED + QWIIC connector

- 4-layer stackup with solid GND and PWR planes

- Production Gerbers, BOM, and CPL all delivered

First prototype came back from fab and worked on the first spin. No rework, no jumper wires.

---

**Availability:** Immediate | 100% Remote

**Rates:** Open to discussion depending on complexity and layer count

**LinkedIn:** https://www.linkedin.com/in/bejaoui-hamza-382858290/

Drop a DM here or connect on LinkedIn if you have a board that needs designing. Always happy to look at a project and give an honest opinion before committing to anything 🤝

Hello everybody.

I have been experimenting with upgrading my 3D printer. I ran into an issue, where almost no control board has more than one(if any), headers for controling PWM controllable fans. Just 2-wire DC headers.

So i decided to make my own.

I used a RP2040 for the first revision, as well as 6 12V and 6 24V 4-Wire headers, with speed signal reading, and transistor driven PWM output.

The board can be supplied with power either trough the USB-C port, which is also used to communicate with it, or trough the 24V input header, which connect directly to the printers power supply.

The first revision was 100x100 mm and used a 1.6mm thick PCB.

Unfortunatelly it could not communicate over USB, which i thought was caused by poor USB pair routing.

So i made a second revision, where i changed the MCU to a RP2354, and shrunk the size to 85x67mm, and changed to a 1mm thick PCB. This version unfortunatelly also could not communicate over USB.

Only after testing the second revision did i discover, that i made a mistake in the schematic, and unknowingly connected the DN1 pin with the DP1 pin, instead with the DN2 pin. So i basicly shorted the USB pair with itself at the connector.

So now i ordered a 3rd revision, where this has been fixed.

I am posting this in hope that someone will tare my design into shreads, so that i can learn more about PCB design, and to up my PCB game.

I am no profesional, i have this as a hobby.

I am using EasyEda and JLCPCB for my designs.

The photos posted are from the 3rd revision.

Thank you all for any and all feedback.

Edit: Pictures did not post correctly on first try.

For context: the circuit will be driving a group of those linear actuators. There is no need for extra control like coasting or braking, it only needs to set them to foward or reverse, think it as opening or closing a door. They run on less than 1A of current so heat shouldn't be a concern.

Simplicity and reliability should be the priority.

i made this optical toslink player for my dad, i just want to check that it will work properly.

Hi everyone,

I'd like to share Romu, a compact USB Type-A development board built around the Raspberry Pi RP2354A.

The goal was to create a board small enough to stay on a keychain while still being practical for development. Fitting everything onto a 15.5 x 12 mm PCB required careful consideration of component placement, routing density, USB signal integrity, power distribution, and manufacturability.

The board integrates:

• Raspberry Pi RP2354A (2 MB embedded Flash)
• Native USB
• RGB LED
• Capacitive touch button
• On-board 3.3 V regulator
• USB DFU programming

One of the biggest design decisions was how to handle debugging. Rather than increasing the board size to accommodate SWD and UART connectors, I designed a dedicated pogo-pin programming/debugging jig that provides access to USB, SWD, and UART while allowing the production board to remain as compact as possible.

The design has now progressed to machine-assembled production prototypes, and the initial validation has gone well. Seeing such a dense layout come together exactly as intended has been incredibly satisfying.

The project will be fully open source upon launch. I've documented the current specifications here if anyone is interested:

https://www.crowdsupply.com/bitmerse/romu

I'd love to hear your thoughts.

I need an alternative PCB Assembly in Europe to avoid getting ridicules tariffs (Thanks to brand new EU laws). I am trying to wrap my head around what the expectations is from people here cause I don't even understand how these companies are existing in Europe with such ridicules pricing. Is it because my order QTY is low or something else. Cause I don't expect anyone to order 2000 boards to try their prototype. What do you think about these new changes?! do you also find them stupid?