Questions tagged [pcb]

PCB is the acronym to Printed Circuit Board. A PCB is a carrier for the circuit's components and their electrical connections.

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Transformer output too high. I'm sure this should be 12V but it is outputting 25V

I have a faulty circuit board taken from a garage opening unit powered by a transformer. I have 25V from each of the transformer terminals (4 of them), 50V on the 24V relays and all terminals have ...
0 votes
1 answer
42 views

Does the temperature affect the working of a PCB circuit?

I use an MP2305DS to convert 12V 5A to 3.3V 2A. The PCB is in a standard IP68 box. Does the temperature affect the operation of the PCB circuit?
2 votes
1 answer
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Resistors on SPI traces

I was looking at the schematic for the development board for the LTC2333-16 ADC, and I was wondering what the purpose of the eleven 33 ohm resistors (R10-R20) on the SPI traces was. There is no ...
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Multiplexer voltage reference

There is a potentiometer on a circuit board that I want to simulate with a DAC. I want to be able to either use the original voltage from the potentiometer or simulate the voltage from the DAC, hence ...
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1 answer
37 views

How to connect multiple star PCB LEDs?

How do I connect multiple star PCBs together? I want to connect some of these in series to create a high-power light system. Should each of these PCBs have a separate heat sink? What should be the ...
0 votes
1 answer
108 views

Robot PCB review request

I am making a PCB for my robots in Altium Designer software. It is my first big PCB project and I want someone with more experience to tell me if everything is all right with my design. I am writting ...
2 votes
1 answer
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Pad-to-Resistor trace too long in datasheet layout example (TLV803E)?

I'm layouting a board that includes the TLV803EF26DBZR voltage supervisor (or reset IC) chip. In the datasheet, it is suggested that the IC is layouted in the following manner: However, I wonder if ...
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1 vote
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Explanation of PCB specification

I'm using this IC - USB5816 SS In this application note, Link, page 7, it is given as, "Consider laminates with low Df ratings at 10 GHz. These lower loss materials include FR408HR, FR408HRIS, ...
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Kenwood Dnx891hd rca output fuse

I have a Kenwood dnx891HD and I've had problems with it for years I finally sent it in due to protect mode and they sent me a picture and told me it was this rca output fuse on the circuit board and I ...
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Two different PcbDoc in one PrjPcb in Altium Designer

I created a PrjPcb with two different PcbDocs. I have completed the first PcbDoc, and now I want to replace one of the chip in the schematic and design a new PCB. I'm making a variant of the chip I ...
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1 answer
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MPPT SMD diode identification

What kind of diode is this (marked with D35)? It is from a MidniteClassic 150 MPPT.
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PCB Layout DRC warning

I designed my own Layout in Kicad, but after running the DRC there are some warnings. Does anyone know what is wrong with the layout? (More info in the attached images). I thought the net describes ...
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2 votes
3 answers
245 views

How to detect if HX711 connected to microcontroller?

I am using raspberry pi pico, HX711 , stepper and RFID. I want to make PCB for it. My system can work with or without HX711. If system has HX711, stepper spins until the weight value of HX711. If ...
1 vote
1 answer
59 views

Is there any difference between antennas applications?

I'm thinking of adding LoRa module to the PCB I designed, and I chose an antenna. NN02-201 The reason I chose this antenna is because I can easily find it in the country I live in. However, LoRa is ...
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2 votes
1 answer
268 views

What are wettable flanks in semiconductor packages?

What are wettable flanks? Is there any difference between packages with wettable flanks and other leadless packages? Can we say the package given above has wettable flanks?
1 vote
1 answer
130 views

FM radio interference on PCB

I have designed a few PCBs for one of my projects. The PCB is picking up FM radio signals. I can see this as spikes in the spectrum where each radio station is broadcasting. I tried covering the PCB ...
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1 answer
99 views

Washing of an IC

Can someone tell me what is the information regarding the process of washing the device during production? This question is with respect to the Microchip LAN8741A
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1 vote
1 answer
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What are these two components?

I need to replace these two components but searching for the markings on them yields no results. Does anyone know what they are?
8 votes
4 answers
549 views

Impedance matching in 2-layer FR4 board

I'm not that familiar with high-speed boards designing. Here I want to route the PCB in a part of which I've used a LAN8720A as the PHY of the ethernet system. According to what I've read about ...
2 votes
1 answer
46 views

How to solder a micro USB port with chipped pads?

What are the strategies for soldering a micro USB port which has broken and chipped-away pads? See the picture for details.
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3 votes
1 answer
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Separation of digital and analog grounds in evaluation board

I am designing pcb for AT86RF215M tranceiver. The datasheet for it states that: AVSS is the analog ground; DVSS is the digital ground voltage. The analog and the digital grounds should be separated on ...
11 votes
1 answer
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Are surface mount or through hole connections more reliable for safety critical applications?

While obviously factors like safety certifications and margins of error are more important when it comes to safety critical applications, e.g. aerospace, I saw an article that said that one of the ...
14 votes
1 answer
2k views

Why are non-conductive circuits designed on PCB?

This is the PCB of the network communication industry. What I know now is that after adding these redundant non-conductive circuits, the performance is improved from Cat3 to CAT5e. I really want to ...
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Programming a custom made STM32 board via USB

I've designed a custom board using STM32g431cb for a project recently. My goal was to be able to program the board via both stlink and the usb port depending on the preference. I used the USB_DP and ...
1 vote
0 answers
32 views

Identifying pins on a micro SD card interface on the PCB side

I have a Pyle motherboard from an Android-based car audio receiver which has an interface to an SD. I'm trying to identify these pins to make a flat cable to connect a homebrew micro SD card slot. In ...
0 votes
1 answer
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Resistive finger PCB button

I want to do something similar to this question: PCB "Touch" Button However there the PCB was not described that much. I have a design where each 'finger' is 1mm apart. And I'm not sure ...
2 votes
1 answer
54 views

Best ways to mask missing toner after toner transfer PCB etching

I want to make a general guide for masking the missing toner on copper clad after toner transfer. The masking methods I know so far: Permanent marker (some say it doesn't work, I am intimidated by it ...
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1 answer
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TPD8S009 ESD port nomenclature matter

I'm designing with a TPD8S009 part, and I'm not strictly following the D0+, D0- array stated on the chip. I'm connecting it as shown in the below snapshot. Is this okay? The datasheet simplified ...
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SOT23 package jumper [duplicate]

I’m replacing some components on existing PCB, and I need to replace transistor in SOT23 package with a jumper. Problem is that none of the standard jumper packages are not suitable for more than a ...
1 vote
1 answer
80 views

Possible to separate D+ and D- on 2 layer board?

I am trying to make a PCB adapter, where the connections are USB-C, so need to cross connect the D+ and D- on both connectors. Is it possible to run D+ on top layer, and D- on bottom layer? Attached ...
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4 votes
2 answers
150 views

PCB design review: Questions about power/ground plane

I am designing a small four layer PCB with KiCad. The purpose of this PCB is to control and monitor the lights of a car (not for road use) and without having to resort to old relays and fuses. I have ...
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2 answers
63 views

PCB design review (ATmega32U4 keyboard PCB)

I've been working on an ATmega32U4-based PCB for a custom keyboard for a while now. I made a few prototypes with similar designs, but they all seemed to have issues with the microcontrollers dying ...
0 votes
3 answers
103 views

Long PCB breadboard [closed]

I'm looking for a PCB breadboard longer than this one: I spent a long while searching without success. Any clues or confirmation of futility of further search would be greatly appreciated. Here is a ...
4 votes
5 answers
538 views

PCB design for air quality measurements

I want to make a simple PCB with the following components: 1x CO₂, humidity and temperature sensor - SCD40 (Qwiic) from Sparkfun 1x 1.3 inch OLED display I2C SSH1106 from AZDelivery 1x TinyS3 (ESP32-...
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QFN-28 REVERSE Breakout Board

I am trying to build a PCB board that I found on GitHub. In a rash we ordered few sets of the PCBs without inquiring about the parts availability. Turns out one of the parts is not available in all ...
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4 votes
2 answers
2k views

What is this electrical component called?

I have this part in my lab that looks like a chip holder with pins. I tried googling that, but nothing comes up. I am interested in this part and I was wondering if it comes with a lid, but I need its ...
7 votes
5 answers
728 views

How to daisy-chain boards in a PCB stack

I'm looking for a connector that is both daisychainable and lightweight (and possibly, thin). Currently, I'm using ribbon cables (male pin header and IDC female connector) and using the same cable to ...
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7 votes
2 answers
803 views

What happens if high via current flows in PCB?

If I used a via of 8 mils diameter with 20 um thickness. As per sierra tool calculator it can carry current of 1 A at 10 degree rise in temperature. What happens if the current is more than 1 A? When ...
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2 votes
3 answers
57 views

Ethernet: best placement of magnetics and PHY IC in multi-board stack up

Given the image below, what would be the best place to place the PHY and Magnetics, (connectors can move)? I appreciate that Ethernet best design practices are not being followed here, but given this ...
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Freerouting unable to route

I am trying to route the PCB I designed in KiCad with Freerouting's autoroute feature, but have noticed that it seems to be unable to route one of my LGA-12 ICs (U2 on the board shown below). What are ...
2 votes
0 answers
88 views

White residue on circuit board

What is this white powder on my induction cooker hob? Is is metal salt? The capacitor recently melted
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1 vote
0 answers
28 views

LED status for 2.5" SSD NVME

I'm making a PCB for the NVME SSD connector, and I want to put a status LED on it, but I didn't find much info about it. I found a pinout, and one of the pins is called activity (P11). I thought it ...
0 votes
1 answer
44 views

Display contact using foam - how is it working? [duplicate]

I was pretty stunned when I disassembled my Sonoff TH Elite by the way the display was connected to the PCB. Somehow the "foamy" piece is pressed onto the blank contact surfaces of the PCB ...
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2 votes
1 answer
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Drawbacks and disadvantages of insulated metal substrate PCBs

Insulated metal substrate (IMS) PCBs, with variants and names including aluminium base, metal clad printed circuit board (MCPCB) and thermally conductive PCBs have some sought-after features in terms ...
1 vote
1 answer
46 views

Tri-state pin on oscillator chip

I'm stuck trying to find an oscillator chip which can be used to provide a clock to a W65C02S at, say, 12MHz. This is the S7D12.000000A20F30T - with 12MHz output, 5V input. So now my only question is,...
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2 votes
4 answers
337 views

PCB design with buck converter evaluation

In my project I have a 15 V power supply and I have to step it down to 3.3 V and 5 V for to use with PCB components. At first I tried using an LDO, but it heated up too much, to a point where it ...
3 votes
2 answers
82 views

Is there a maximum differential skew in Ethernet communication?

I am working on a device that runs 100 Base-T. When routing the differential pairs I was wondering if there is a maximum differential skew specified somewhere and if so, what is it? Is there a formula,...
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1 vote
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PCB thermal simulation with MOSFETs

I am looking to simulate thermal performance of MOSFETs on a PCB and would like to get recommendations of ways to do it. Some considerations would be Multiple MOSFETs are in parallel with control ...
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2 votes
0 answers
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ESP32 not able to detect any I2C devices

I am trying my hand at building a smart watch from scratch. I just got the latest PCBs delivered and upon soldering everything I found that the TTGO micro-32, essentially an ESP32, cannot detect any ...
1 vote
2 answers
46 views

Is there any way to get 2 sided FPC with stiffener?

We need to design an FPC board that consists of components like mezzanine connectors that are centered on 2 sides, top and bottom layers. We have concerns about attaching the FPC board to the main PCB ...
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