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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.

7
votes
2answers
448 views

what is the purpose of having a “thru cal” on RF PCB?

I often find a thru cal on RF PCB like picture below. What is the purpose of having this thru cal thing on the board? One purpose I can think of is to test whether the designed transmission line is ...
0
votes
0answers
46 views

Help! How can I repair this PCB [on hold]

I have a PCB that I believe to have suffered very minor damage due to water ingress. The PCB has this LCD attached. https://www.mouser.com/datasheet/2/281/20lcd-41581.pdf Currently I am getting a ...
0
votes
1answer
38 views

Maximum allowable voltage between PCB traces

I have some confusion regarding the guidelines for clearance between surface uncoated PCB traces (specifically component pads). IPC-2221 guidelines and other guidelines and standards indicate spacings ...
0
votes
1answer
69 views

Seared my circuit while checking voltage

I was attempting to diagnose a problem with my dvd player as I was not getting any power, I wanted to use my multi-meter to see where the circuit was shorting out, I set the setting on the multi-meter ...
0
votes
1answer
45 views

Crosstalk between AC and DC

First time asking a question but I've come across something I just can't find the answer to. Whether or not it's because a silly question I hope to find out. So I understand that with crosstalk ...
0
votes
1answer
29 views

Need help finding proper Led driver IC

i am an electrical engineering student and have been tasked in creating a quite interesting project. Basically , the whole PCB with the microcontroller and all other parts is already designed, however ...
-1
votes
0answers
70 views

NanoPi Neo4 Power supply scheme help

Title might seem a little misleading, but honestly quite hard to word a title for my particular problem. The board design I'm working with combines the NanoPi NEO4 minus specific components which I ...
1
vote
4answers
90 views

Selecting coaxial cable and connector for PCB referring to required frequency

I want to transmit my 24GHz signal from PCB through coaxial to antenna. I wonder how to chose best match for it, also the power is -5dBm, 50 ohm. It's based on ADF5901 2ch PA. I have found two good ...
1
vote
1answer
56 views

Good resourses to learn PCB designing [on hold]

I am a beginner at PCB designing. I believe a good way to learn to design PCBs is to design them myself and then check how I did. I wanted to know of any resourses where people post their PCB designs ...
0
votes
1answer
40 views

Powering a PCB chipset via POE switch [on hold]

Disclaimer: I have very little clue of networking switches or POE. I have a POE switch, a PCB taken out of an Android TV Box, and a WiFi router. I want to provide both power and data to the chip ...
1
vote
3answers
124 views

PCB design for outdoor use without coating

I am making a PCB for a home project: a small weather station that I will place outdoors to collect data. There is now a question of environmental resistance. I can mill out the PCB for free on a ...
0
votes
1answer
47 views

Eagle - Custom pad shape for SMT inductor

I'm trying to make the following footprint in Eagle for an SMT inductor: I understood how to make D-shape pads and similar, but this is driving me nuts: my idea was to enclose a pad into a polygon ...
0
votes
1answer
104 views

handcrafted PCB problems

I have attempted to make this board below at home. Applied negative photoresist paint, left to dry for about 4 hours each side over a radiator, applied a double layer tracing paper with the artwork on ...
0
votes
1answer
58 views

Does a Vcc layer cause noise to a 4-layer RF PCB?

I'm designing a 4 layer GPS tracker PCB with the 2nd layer as ground and 3rd as Vcc. Is this a good practice? I know a gnd layer is good but I'm not sure how to distribute the positive of the supply ...
0
votes
2answers
66 views

Reed Switch Failure Modes

I've been playing with these through hole reed switches: MDSR-4-12-23. It has been my experience so far that you have to be very careful in handling them, including when bending the leads to 90 degree ...
1
vote
1answer
62 views

Contradicting ideas about differential signal route, confining fields vs Increasing impedance

By initial sense I think we must: keep pair intra-distance as close as possible for field cancellation. Fill surround of pair with GND plane and have via near to it to confine the fields, prevent ...
0
votes
0answers
46 views

Perfboard dimensions

I would like to design a 3D printed enclosure for my project. I am using these perfboards from amazon. I could not find online the dimensions for the mounting holes. I know I can use a calliper, but ...
3
votes
1answer
71 views

Is my pin understanding correct on the 2N3904?

I have the following in my circuit: Am I right in understanding that the pins top to bottom are: 1/Emitter 2/Base 3/Collector where the top square pin is Emitter, middle pin with red trace is the ...
0
votes
1answer
65 views

Impedance matching in multi-layer circuits

In a new circuit design, I need some impedance matching for some high speed traces (i.e. Ethernet, USB, SD card...). Usually I define tracks width with this web tool https://www.eeweb.com/tools/...
2
votes
2answers
539 views

How do I remove unnecessary fills in an EAGLE polygon?

There are a lot of resistors and diodes on the board, where the polygon passes like this. How can I get rid of it?
0
votes
3answers
174 views

How to route Ethernet PCB ? [closed]

I am new to PCB routing. In one of my projects, I need to be able to exchange data between nano-computers (https://www.variscite.com/wp-content/uploads/2018/01/DART-6UL_DART-6UL-5G_Datasheet.pdf) ...
0
votes
0answers
49 views

Should right angles at pads be avoided in traces on a PCB?

I have been told that traces shouldn't bend at 90 degrees or less, because electrons get trapped in those angles. Does the same also hold for when traces meet at pads? Is the left pad in C2 ...
1
vote
0answers
88 views

Female symbol on PCB silkscreen?

You can see the symbol on the upper right hand side of the board, what appears to be a pictogram of a woman wearing a dress, similar to a bathroom sign (?) Wondering what this is.
3
votes
2answers
158 views

Can I convert a mini guitar-amp into a portable auxiliary speaker?

Being a guitar player, my brother got me one of those guitar shirts for Christmas that has a board with pressure sensors attached to it and an actual miniature amplifier. When the sensors on the board ...
0
votes
1answer
60 views

Solder or Adhesive for Wifi Module

I am replacing a wifi module for my smart tv. I have any never done this before and want to know if I need to solder the two components together or just use an adhesive like in the old module. The ...
-1
votes
1answer
96 views

Software for PCB servicing, boardviews how they are created

Boardview files containing information about printed circuit boards, their components, used signals, test points and more (popular in laptop/pc service). These files may have following extensions: ....
0
votes
1answer
135 views

Overcurrent protection for DC motor [closed]

I found a circuit to protect DC motors from stalling: this is the schematic: and this is the board I made based on that schematic: When the power is connected to the circuit makes all LEDs on but ...
0
votes
2answers
56 views

Bus vs Signal Harness in Altium

I am designing a Schematics for one of my big project. I am using Hierarchical Design for my project. My Schematics has one processor which has 5 UART. The UART nets have names like ...
0
votes
1answer
37 views

Struggling with patch gps smd antennas connections

I'm struggling with antenna connections to GPS module in my PCB design. My antenna is a smd passive patch antenna, "SGGP.25.4.A.02 from Taoglas". The antenna shape and recommended footprint is in the ...
2
votes
2answers
99 views

Troubleshooting defective LED bulbs

I bought 10 Thomas Watt LED bulbs and 8 are dead in less than a year (each last about 2-3 months). Soometimes a couple of days before they stop working, they flicker when I switch them on or after ...
0
votes
4answers
81 views

Attaching wires to a SMT footprint

I have a pre-made motor controller which I want to re-purpose for a hobby project by pulling the MCU off and attaching to a custom control circuit (with a more powerful MCU, current sensors, etc). The ...
0
votes
0answers
41 views

Calculate inductance of chokes for a induction heater

simulate this circuit – Schematic created using CircuitLab I´m trying to build an induction heater, I have builded four of them and only two worked, one of these blew up both IRFZ44N (first it ...
0
votes
1answer
23 views

How to reverse the pinout of connector in Eagle

I have a screw connector with multiple pins and it seems like it will be easier to do the layout if I reverse the pinout on the connector. So if I have a 3 pin screw connector I would just need to ...
0
votes
2answers
113 views

First pcb design is it safe?

I have designed a pcb board (2 layer) that deals with high voltage 220VAC and it also converts it to 5VDC and 3.3VDC. So, because it is my first design and I deal with high voltage I want to be sure ...
0
votes
1answer
60 views

How can I attach a custom built antenna to the NodeMCU (ESP-12E)

Is there any possibility I can disable/remove the PCB antenna and replace it with a custom one, like a directional helical antenna? Can I just solder it on? I am an absolute beginner and have no real ...
0
votes
1answer
102 views

Removing the smallest supply decoupling capacitors in multilayer boards

Hello I want to make PCB for ADF5901 24GHz power amplifier, it says use 3 capacitor for each supply pin, 10pF, 1nF and 100nF. we have about 6 supply pin. Can we remove 10pf bypass from all pins, If ...
0
votes
2answers
55 views

Increasing PCB trace current capability by duplicating on other layer

I just came across this video: https://www.youtube.com/watch?v=fxC5w3f8FkY which says that I can duplicate a trace on the bottom layer and then at the end just via it back up to increase the current ...
0
votes
1answer
50 views

Isolating a small pin on a flat cable

A motor on my HiFi system (which is supposed to lift a volume controller) has broken. The motor is stuck and I don't want to fix the mechanical part. I assume disassembling the volume controller would ...
0
votes
1answer
61 views

Heat sink via holes under voltage regulator LM2596

I am designing a board with LM2596 voltage regulator (12V/5V 3A) I want to make heat-removing holes under the microcircuit. For this, I decided to use via holes. The board has two layers. The ...
7
votes
2answers
77 views

Component designators on multi-pcb projects

I am currently working on a project that goes over multiple PCBs for the first time and realised that i don't know what the "standard" or best practice for component designators over two (or more) ...
6
votes
3answers
792 views

Fuse 125V/4A can be replaced with 250V/4A?

I want to replace a blowed fuse 125V/4A but it is rare to find them. Can I use instead a 250V/4A ? I read at https://www.mojotone.com/support/Knowledge-Base/Is-it-ok-to-replace-125v-glass-fuses-with-...
1
vote
3answers
101 views

Adding Debug LEDs to PCB

I'm working on the next revision of a prototype PCB board, and from the first one I learned that LEDs would be very helpful instead of having to probe each pin/wire for a certain state. In this ...
1
vote
2answers
104 views

How are plated through holes (PTH) made? [closed]

I want to know how plated through holes (PTH) are made. Also, what chemicals are used in it and with what quantity?
0
votes
0answers
39 views

What connector can be used for dimmer output?

I have some poorly designed PCB board (LED dimmer), through-hole mounting. The output is in the left corner, it have 8 x 0.1" pitch pin mounting holes for connecting line-in, power, and output (H,M,L,+...
4
votes
1answer
32 views

Is this possible to make a module with both castellations and LGA?

I am trying to decide on a pinout methodology for a module that will be assembled board to board on a bigger PCB. considering the pros and cons of LGA vs. castellations(cut half vias), i was thinking ...
1
vote
2answers
74 views

Problem when adding teardrops in Altium

It seems easy to add teardrops for connections in Altium. But in my design, after adding teardrops, it throwing errors which indicating the 'teardrops' violate my clearance constraint such as: ...
1
vote
2answers
89 views

Does this prototype match the schematic?

I'm following this project which shows how to make an OpenTherm Adapter for an Arduino. It includes this schematic: Along with this simplistic PCB diagram: I am now in the process of making my own ...
2
votes
1answer
72 views

Major causes for routing cut residues on a PCB board and how to prevent it

I am not sure if it is the appropriate to post this question here. I have a question regarding PCB SMT process. We found some PCB board after de-paneling using router cut, some of its residues being ...
0
votes
2answers
62 views

Can water condensation appear on PCB in IP67 enclosure box?

Does IP67 box protect PCB from moisture? If not, is it OK to have an outdoor air humidity sensor soldered on PCB in IP67 housing? Also if it doesn't block moisture, is there any reason to use IP65/...
3
votes
0answers
68 views

JTAG trace length affecting programming ability

I've recently had a design made that requires a programming port to be located quite far from the device I'm trying to program. This has meant that my cJTAG traces are around 13cm long. I think as a ...