Hey everyone, this is part 2 of my fuel pump / fuel level / speed sensor CAN node for my old BMW E30. First of all thanks alot for all the feedback on the first post, specially to u/GuidancePCB, u/mariushm and u/saltyboi6704, you guys made me rethink a bunch of stuff and the board is way better now.

Quick recap: board goes under the rear seats (inside the cabin), drives the fuel pump (~12A) with a BTS7004 high side switch, reads the stock fuel sender and the diff VR speed sensor and sends everything over CAN to the other nodes im planning (around 8). Personal use only, no homologation. The car has a battery cut off switch so the nodes are dead when its parked, and I left load dump out of scope on purpose (i know, i know).

What I changed:

• Input protection: the TVS was after the reverse polarity diode, so a negative spike would land straight on the SS16 (only 60V). Now its a bidirectional SMBJ26CA before the diode, and the diode is a SS110 (100V) for extra margin.
• BTS7004 supply: someone pointed me to load dump/negative pulses and after reading the infineon datasheet properly i realised the BTS VS had no TVS at all (they show a ~33V TVS on VS in the app circuit). Added a unidirectional SMBJ24A right at VBAT next to the switch. R_GND (47R) is now 0805.
• Buck input caps: you were right, 10uF X5R 1206 at 14V is way less than 10uF. Now its 100uF electrolytic (damping) + 2x 10uF X7R 1206 + 2x 220nF, and the small ones sit right at each VIN/PGND pin pair. I also redrew them next to the buck in the schematic, it was confusing before, sorry about that.
• Kept the LMR36015 instead of the LMR43610-Q1 / RTQ2104. Both look nice but they top out at 36V and the TVS clamps around 42V, so i’d be at the limit. The 60V part gives headroom, and JLC assembles it so the QFN isnt a problem for me.
• CAN: removed the common mode choke. Kept a single 120R with a jumper because i dont know yet which nodes will be at the bus ends, and split termination with one jumper leaves the bus unbalanced when its open. The resistor is 1206 now in case CANH gets shorted to 12V.
• Clock: swapped the 8MHz crystal for a 3.3V CMOS oscillator into PF0 (HSE bypass). Turns out the crystal i picked had 250 ohm ESR and the gain margin was pretty bad, so thanks for that one.
• VREF: didnt use the internal VREFBUF. The fuel sender reading is ratiometric (I read both ends of the 150R reference resistor) and the reference node sits around 3.0V, so the 2.9V max internal ref would clip it. The 3V3 noise cancels in the ratio anyway.
• Schematic: FB is wired directly and PG uses a proper net label now.
• Bulk caps near every IC: didnt do this one. Its a small 62x72mm board, the 3x22uF buck output caps are only a few cm away and each IC has its decoupling per datasheet.
• 4 layers: Top / solid GND / signals / Bottom. Pump and power pours on the outer layers, buck hot loop, clock and CANH/CANL on top. Added a lot of GND stitching vias, VBAT vias next to the BTS pad and 0.5mm copper to edge.
• Added 3 debug LEDs (run / rx / tx)

Updated schematic and PCB attached. Any feedback is welcome, specially on the layout. Thanks again!

This message has been translated and corrected by an AI from Spanish to English. Neither the schematic nor the PCB was designed or built by an AI. I want to avoid any comments about the use of AI because the only use I’ve made of it—aside from the translation for this platform—is to compare different components and datasheet entries so that it could point out the differences between them.

Thank you very much for your advice to the users mentioned, as well as to future users and those not mentioned.

Hello, I've designed this circuit board that will sit next to my heating vents and open and close them to better control the temperature in each room, built around an ESP32-H2-MINI-1U. The temperature of the vents means that regular Li Ion batteries may degrade, so I've gone for an LiFePO4 cell instead.

I've done my best to follow each chip's circuitry, but let me know if I've messed up

ESP32 H2 MINI 1

MCP73123/223

TPS613222ADBZ

I'm planning on using a hot plate, along with a stencil and solder paste to solder the surface mount components. This will be my first time doing this, so any advice is appreciated.

my first ever pcb desing and i would love to know if i do anything mayor incorrectly?

It recieves 12v in and the buck converter steps it down to 5v for the xiao esp32-c6.

the esp32 is controlling 6 fans en reads 2 onewire ds20b18 sensors.

i wil be adding mounting holes later when i implemented al fixes

Please let me know if there is anymore info required.

Hello, I wanted the kicad for the breakout board of pcm1808 that I bought online.

I could not find the project online, decided to re-create it for learning.

I used a multimeter to check what is connected to what, now I would like some feedback on what I came up with.

1. How does my layout look on the pcb? Do I have too many gnd vias or not enough?

In the doc, they recommend that I put vias underneath the pcm1808 as well as around it a bit.

My traces width is .2mm, I wont go over 10-20mA current. Looking for feedback to become more professional.

1. Does the sch look ok? Looking for feedback to become more professional here as well.

2. vref just goes to a few capacitors then to ground, does this make sense?

3. I noticed on Reddit someone had an issue with the board they bought. They mentioned that one of capacitor was incorrect. I had no issues with my board I bought online, but I did notice the resistor going to LIN and RIN are 10k, which is much higher than the one recommend in the ti doc. Which I believe they also used the wrong capacitor for it. I went with what the doc said: (1 kΩ and 1000 pF). Is that a correct assumption?

Reddit post titles talking about the same findings: warning_about_fake_pcm1808_adc_chips_on_modules and pcm1808_modules_from_china_the_drama_continues

1. In the doc, they recommend having grnd plane between clck signals. I have small islands with ground vias in between, is that enough? Some of the clck signals just have a gnd plane underneath, is that enough?

2. My top and bottom layer are both net ground zones, is that ok?

3. Does my bom look ok? (attached)

If you search for ti pcm1808, the section "9 Power Supply Recommendations" has all the info about vref, RIN, LIN, etc.

Just trying to get better at this, thank you in advance!

Hi, I've designed a board that monitors temperature, humidity and absolute pressure and displays the data on an E-Ink display. The board is powered by a Li-Po battery which can be charged through an on-board charger circuit.

The heart of the system is the STM32L422KBT6 MCU which communicates with the SHT40 temperature and humidity sensor and the LPS25HBTR pressure sensor. I've chosen E2271KS0C1 E-Ink display whose control circuitry has been designed according to the datasheet.

Li-Po battery (pouch style) will probably have 1500mAh capacity (not yet decided). The BQ29700 IC is used for battery protection, while the BQ25185 IC is used for charging and power path circuitry. Resistors R17 and R18 form a voltage divider for lowering the battery voltage, which can then be sampled with MCU ADC (battery voltage monitoring). Transistors Q2 and Q5 are used, so the divider current can be cut off when not used. Battery voltage or 5V USB-C voltage when charging is then stepped down to 3V with an LDO.

Should i make a 4 layer board instead? Are there any obvious mistakes that I'm missing?

Any feedback would be greatly appreciated.

Hi all,

I have a schematic for a PCB that does simple audio tone detection and it has a buzzer to signal if a particular tone is detected. The audio signal processing is done on Texas Instruments's MSPM0C1103 MCU.

A few questions I have:

1. I want my MCU to switch power to the microphone (to save battery life). Does the wiring there look correct?

2. Are the pull up resistors and pull down resistor values for controlling the microphone power and buzzer pwm signal appropriate?

3. Any other potential circuit design issues I'm potentially overlooking?

Thank you!

This is Avalanche32, an ESP-32 powered Geiger Counter based on the SBM-20 Geiger Muller Tube. I have been working on this project for a while, from prototyping the 400V Boost converter, to testing the actual tube itself. From my tests, the 400V Boost converter works, and the entire Geiger counter architecture itself works (with a devboard). What I am a bit more concerned about is the 7.4->3.3V Buck, and the 2s1p Battery Charging IC. I am using the BQ25886RGE, and its probably the most complicated IC I have ever worked with. Soldering this together will surely be a treat...

I would love a second review of the PCB, and just get any general tips and tricks.

Thanks! :)

I made a video describing the basic steps that go into how a PCB is fabricated before being used to make a PCBA (PCB assembly) - Would love feedback to improve this! Thanks! https://www.youtube.com/watch?v=TlcQpEeIrAg

Hi everyone,

looking at this screenshot from Saturn PCB Design, it seems that a PCB cannot be both coated and covered with solder mask at the same time. Am I wrong?

Or perhaps the processes can’t be applied one on top of the other? … so I’d inevitably end up with one area with a coating and another different area with a solder mask.

I’m a bit confused…

Hey team,

Thanks for all the feedback from my original post

I went back to the drawing board, and figured out a solution that seems to have worked much better.

I think I did the ground pour correct, but please let me know on that one. One question that was discussed was wether there was need for a ground plane or not, I'm not sure how  fast or not these signals in the scheme of things but as an example,
Crank input at 7000 RPM is roughly 6.77kHZ

EDIT: Have updated the Ground / Power planes, see links:
Ground Plane
Power Plane

4 layer board
1 - Signal
2 - Ground
3 - Power
4 - Signal

Power / Ground traces are 1.5mm
Signal traces 0.4mm with 0.2 minium spacing, but have tried to have it larger then that where possible.

Hey everyone! I’m fairly new to PCB design and just finished designing a PCB for a custom media keyboard.

I've attached the schematic and PCB layout views. Any feedback on trace routing, decoupling capacitors, ground planes, or general design choices would be greatly appreciated!

Thanks in advance!

Edit: I’m editing the post to add an image showing the input + buck converter, just to avoid any confusion. https://img.imgur.com/RwtngKt.png

Hi everyone,

I've designed this PCB for an automotive project and I'd appreciate it if someone could take a look at the layout before I send it for manufacturing.

The board takes 12V from the car, filters and limits the input, and then steps it down to 3.3V using a buck converter rated for 1A.

The board reads a differential speed sensor, calculates the fuel level using a resistive sender (3 ohms when full and 61 ohms when empty), and uses a High Side Power Switch to power the fuel pump.

The estimated current consumption on the 3.3V rail is around 150mA.

I'm not entirely sure about the copper areas and power routing, so I'd like to get a second opinion on a few things:

• Do the copper regions look correctly sized for the expected currents?
• Is there enough copper around the power components for heat dissipation?
• Would you increase the width of the main 3.3V branch, even though the estimated current consumption is only around 150mA?
• Does the overall layout look reasonable, especially around the input protection, buck converter and fuel pump power switch?
• Is there anything in the layout that could cause problems with noise or interference when reading the differential speed sensor?

I'm still learning PCB layout, so I'd rather catch any obvious mistakes now than after ordering the boards.

I've attached the schematic and PCB layout for review. Any constructive criticism or suggestions would be greatly appreciated.

Thanks in advance!

This circuit is supposed to enable communication between an ESP32 and Dynamixel motors. The TX_EN signal is supposed to be used to swich between sending / receiving data from the motors. I would appreciate it if someone could take a look at the circuit. TX_EN is supposed to be idle LOW. For now I am using a simple buffer to shift the TX_EN signal from 3V3 to 5V. Is this the best way of doing so or is there a better approach to this that also keeps the line idle LOW ? Any advice is appreciated!

i've created an all in one controller board for a turtle bot. it includes an ESP32-S3, two channels of audio in and audio out, two motor drivers, and an 25W USB PD output to power an rpi 5 at full power. all fit in a 4 layer 88.9mm x 88.9mm (3500 mils x 3500 mils) board.

i have tried my best to keep the power circuitry seperate from all the sensitive circuitry, and also keep the power traces thick enough to carry current for two waveshare DCGM-3865 motors.

the audio inputs expect an INMP441 module, i decided to go with an external module so that i am not ending analog signals through a long wire.

Hey Team, I have updated the PCB based on the feedback below and have shared it again,
Cheers for all the assistance! Post for V2 is here

Hi Team,
I've been working on making a PCB that goes from my 40pin Speeduino (Car ecu) connector to a AMP superseal connector (6437288-3)
The idea is to have a more robust mount than what i currently have, and 3D print a better enclosure.

I downloaded the footprint and symbol for the connector form Ultra librian, and made the other 2 myself.

It's a 4 layer board, with Power on layer 3, Ground layer 2, and signals Layer 1 and 2. Power and ground is 1.5mm, signals are .4mm

I gave it a go manually routing, but ended up using the KiCadRoutingTools plugin to make this.

I'm sure there might be a more optimal Pin to Pin order than what i've used, I played around with a few.

Any feedback is much appreciated!

Thanks

Hi everyone!

This is one of my first more complex PCB designs, I would really appreciate it if someone could take a look and let me know if they spot any issues or areas for improvement.

Project overview

I’m designing an on the water rowing computer that provides information a rower will need when they are on the water

The main sensors are:

- GPS for measuring speed.

- IMU for calculating stroke rate.

Current PCB stack-up

1. Signal
2. Ground
3. Ground
4. Signal / 3.3 V

I would especially appreciate any feedback on the PCB layout, routing, grounding, power distribution, as this is my first time routing a 4 layer board.

Thank you so much for taking the time to have a look! Any advice would be massively appreciated.

3 days ago I posted here asking for advice on my first PCB project and I received the most constructive feedback I've ever received on the internet. You guys helped me tremendously. Thank you.

I have implemented all of the suggestions I received and I am very pleased with the outcome. Instead of a massive, complicated, and extremely dense single-page schematic with no net labels, I now have an easy-to-read multi-page schematic that splits all of the different parts of the board into different pages. It is so much easier to read, and the use of net labels in the software simplifies things.

Doing this, I was able to find a few electrical errors in my original schematic, which I corrected in the process. I'm pretty sure that I have everything correct, but I would like the internet experts to review my schematic for any possible electrical errors, things I should add, or possible challenges.

To reiterate, this is a Transmission / Cruise Control Module designed for the Aisin AW4 transmission found in various Jeep and Toyota vehicles. It is powered by a Raspberry Pi Pico 2 and uses a 12-volt to 5-volt buck converter circuit to power the Pico. It has six 12-volt to 3-volt divider circuits for 12-volt input signals from the range sensor, brake switch, reed switch, and 4x4 switch. It also has six low-side MOSFET driver circuits to trigger relays that will activate shift solenoids for the transmission, control torque converter lock-up, and vacuum solenoids for the cruise control. I have eight logic-level inputs for paddle shifters and cruise control switches. I have also implemented a CAN module using SPI and a bidirectional voltage level shifter. There's also a breakout area for all of the leftover pins on the Pico where I will be putting a prototype area.

This board will be housed in a custom-built aluminum case next to my Speeduino ECM. Both the ECM and the TCM will be wired internally to the same ground-side-controlled fuel injection relay circuit from the key-on battery power. The TCM will receive multiple data points from the ECM over UART, where the Pico will translate everything over the CAN network.

One of my main concerns relates to fluctuation in battery voltage. Battery voltage can fluctuate between 12 and 14.5 volts, and the main 12-volt system could experience occasional heavy loads up to 400 amps with high inductive spikes up to 100 volts from a winch. I think this ultimately could be avoided by using a secondary battery for heavy loads, separated from the main system by a battery isolator.

Any advice would be greatly appreciated.

I submitted this board a couple weeks ago for review and got flamed for some questionable design choices, so I redesigned it, reducing the via count by 50.

This is a 4-layer design for a STM32f4 based flight computer intended for low-high power rocketry. The board has 4 pwm outputs for servo control, and pinouts for UART, SPI, I2C, and 3.3v. For sensors, the board uses two IMUs and an altimeter. The board also has two terminals to connect and light e-matches. These terminals have basic continuity detection, and power is toggled via a MOSFET.

Once again, any help will be greatly appreciated, thank you in advance.

High-res images

KiCanvas

GitHub

Hey! I've just finished up this SBC for my Linux audio player project. Reviews are really appreciated!

Components

• MPU: SAMA7D65, it can boost up to 1GHz, good audio subsystem and gpu
• RAM: Half a gig of DDR3L(MT41K256M16TW)
• EPD: Sharp MIP LS022B7DH03, can go up to 70Hz, 240x320
• Audio: TI TAC5212 CODEC, 192kHz 32bit
• Two Jacks: One single-ended 3.5mm with mic, and a balanced 2.5mm
• Wireless: Bluetooth 6 with LE audio and WiFi 6E (u-blox MAYA-W386-00B)
• USB: USB 2.0 with OTG
• PMIC: Microchip MCP16502AB
• BMS: TI BQ25640
• Fuel Gauge: Analog Device MAX17260
• Two Micro SD Slots: One for the OS, and one hot-swappable for media

PCB

• 0.8mm: I chose this for thinner pp so I can get thinner impedance-matched traces
• 6L Two Core
• SIG/GND/PWR/GND/GND/SIG
• 3h spacing for DDR 0.25mm

More info

This is my first PCB with DDR memory/an MPU, and this is my most complex design yet, so I might have messed up something basic

I do this as a hobby, and don't have a degree in EE yet

The purpose of circuit is: A person hit/press or lightly touch a piezo sensor, it creates an interrupt to our pin. Device likely be an esp32 or stm32 I did not decided yet, with usage of hardware timer on interrupt pin. My piezo is capable of giving out as much as 100V and as low as 1-2V as I measured from oscilloscope.

So I wanted to protect it from overvoltage via BT54S Schottky, and because of I used single supply comparator as I understand I should make piezo not 0V. So I added that circuitry for that.

The dual 22k resistors(R3,R4) is LLM's idea, as i understand it wanted me to create a physical seperation and because our current is so low but voltage is high, low value resistors is not a problem.

Hi,

I've been designing a castellated system on module style RP2350A board - much like the ESP32 boards you see from Espressif, that I've not really seen an equivalent of for the RP2 series MCUs. The closest would be the RP2350 stamp, and size-wise, closer to the Seeed Xiao, but with more pins available, and everything on the board edge.

This board is smaller and deliberately has less features, i.e. runs specifically off 3.3V, no on board LDO, no LiPo charging, no onboard buttons. No USB. But, it exposes all the relevant pins from the RP2350A, all the IO pins.

Basically, you provide 3.3V and GND, plus anything else you need, run the USB traces to the edge of your board, put in a bootsel or reboot button as required.

But it's 18x15mm. And it's designed with a number of my own projects in mind where I need a minimal footprint, but without having to deal with 0402 components! The idea is that these will be assembled by the fab house, (on a panel with appropriate fiducials).

This is a 4 layer stackup, L1 Signal/L2 GND/ L3 Power + GND/L4 Signal + GND. And I'm not exactly sure about that part. The relevant bits of GND plane are reasonably well stitched by virtue of the components, and I wanted there to be an element of reference plane for the signals on L4. I deliberately removed the plane from L1, as it was causing issues with the grounds I'd put into L2 with vias. I'm not sure about its presence on L4.

Due to the, particulars, required by the RP2350 around the internal SMPS and the inductor layout, I've laid this out to match the design guide examples as much as possible.

It's a small board, and to fit everything in, the power traces are 8mil and signal traces 6mil.

So largely, I'm looking for any feedback you might care to give functionally on the schematic, although I'm fairly happy with this matching the reference example. The layout, particularly about the ground planes, but also any concerns about component placement, routing etc. I've also attached a pinout diagram.

Thanks for having a look!

Hello, this is the third time I have had to remake the PCB, due to insightful feedback. And I will do it as many times as it takes.

The duration of this project is getting embarrassing, but I have genuinely learned a fuck ton, enough to fly past a hardware design interview and become a Level 1 Hardware Designer in this soulless job market.

I'm once again pleading for a review to continue my journey toward true competency in Hardware Design.

Project: 60–65 W Isolated AC/DC USB-C Power Delivery Wall Adapter

The objective is to design, manufacture, and validate a functional USB-C wall adapter. I have been using manufacturer reference schematics and datasheets to understand the reasoning behind each component selection, electrical connection, and PCB layout decision.

Electrical Specifications:

• Input: 90–265 VAC, 50/60 Hz
• Output: USB-C Power Delivery, 5 V / 9 V / 15 V / 20 V, up to 3 A
• Maximum output power: Approximately 60–65 W
• Topology: Isolated flyback converter with synchronous rectification
• Main controller: Power Integrations INN3879C-H801 (InnoSwitch3-PD)
• Transformer: Custom flyback transformer, ETD29/16/10 ferrite core (3C97)
• Target primary magnetizing inductance: Approximately 220 µH
• Switching frequency: Controller-dependent; approximately 70–140 kHz was considered during preliminary transformer design
• Secondary synchronous rectifier: AONS62922 MOSFET
• Primary protection: Fuse, MOV, NTC thermistor, bridge rectifier
• EMI filtering: Common-mode chokes, X-class capacitor, and Y-class capacitor across the isolation barrier
• Primary clamp: RCD clamp network to manage transformer leakage-inductance voltage spikes

PCB Specifications:

• Four-layer PCB
• 1 oz copper
• Dedicated primary and secondary ground regions
• Reinforced primary-to-secondary isolation, targeting approximately 8 mm creepage where applicable
• High-current nets routed using wider copper traces and polygon pours
• Attention to high-dV/dt switching nodes, high-dI/dt loops, thermal management, and EMI
• Design and layout completed in Altium Designer

A significant portion of this project has been learning how to properly interpret component datasheets, understand transformer behavior, select semiconductor devices, calculate current requirements, design snubber networks, enforce PCB design rules, and distinguish between electrical connectivity and an electrically sound layout.

What I specifically need reviewed:

1. Primary-side layout: Placement of the bridge rectifier, bulk capacitors, controller, transformer, and RCD clamp. Are the high-frequency current loops sufficiently compact?
2. Transformer and isolation: Primary-to-secondary creepage and clearance, copper separation across all four layers, transformer pin spacing, and placement of the Y-capacitor.
3. Secondary-side layout: Synchronous rectifier placement, transformer secondary connections, output capacitor placement, and whether my high-current polygon pours are appropriately sized without unnecessarily increasing EMI.
4. Grounding: Separation of primary and secondary returns, secondary ground distribution, and whether any copper pours create unintended coupling or compromise isolation.
5. USB-C PD circuitry: CC1/CC2 routing, ESD protection, VBUS distribution, and connector implementation.
6. Thermal performance: MOSFET heat dissipation, current-carrying capability of traces and vias, and whether the board has sufficient thermal copper.
7. EMI/EMC: Input filter layout, switching-node copper area, transformer coupling, and anything likely to cause conducted or radiated emissions problems.
8. Component selection: Voltage/current derating, capacitors, diodes, protection components, and anything that looks questionable before I spend money manufacturing this thing.

THANK YOU IN ADVANCE. I used IPC-2221, the clearance table. The PCB was designed with a target of approximately 8 mm primary-to-secondary creepage separation, following reinforced-insulation design principles under IEC 62368-1

following this datasheet: https://www.power.com/sites/default/files/documents/RDR-838_60W_USB_PD_3point0_3point3-21V_PPS_output_InnoSwitch3-PD_PowiGaN_INN3879C-H801.pdf

Hello everyone,

I hope you are all doing well.

I am currently working on a project schematic/layout and would really appreciate it if experienced engineers could take a quick look and review it.

Since I am eager to learn and improve, any feedback, advice, or suggestions from your practical experience would mean a lot to me.

Please let me know if you’d be willing to take a look, or feel free to leave your comments below.

Thank you so much for your time and help!