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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.

0
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1answer
22 views

Constant current load circuit? (20 amp)

I'm pretty new to stack exchange and I've only just gotten my basic circuit analysis classes done in college. For my school's solar racing team, I've been tasked with designing a constant current load ...
0
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1answer
30 views

Low power 100MHz sinusoidal modulation laser driver [on hold]

I am looking for a low powered laser driver which can modulate pulses at 100MHz sinusoidal. Is this possible, something that you have come across or possible to custom design. I am looking for ...
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0answers
33 views

How to calculate stray capacitance on PCB

I use a 0.4mm spacing between PCB traces (including 0.4mm space between crystal pads and ground) and I believe that's causing stray capacitance. My circuit board is typical (1 ounce copper on FR4 ...
-1
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1answer
36 views

Is it convenient to use a buck converter on a RS-422 communication board?

I am working on a PCB design with STM32 MCU. On the PCB there will be 2 MAX490 transceivers and one bluetooth module. Communication speed will be 921.6 Kbit/s for all communication elements. ...
1
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2answers
80 views

Four Layer PCB doubt

I was looking a raspberry pi zero board, and I think it is four layer pcb, but I dont understand now why the designer used a ground plane on top and bottom layer? It is assumed the four layer pcb has ...
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0answers
56 views

How to clean circuit damaged by bleach?

I was trying to remove stains on a fiber optic party tie using bleach, however it seems a small quantity has leaked inside the controller overnight, causing some corrosion and preventing it from ...
0
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3answers
76 views

Can someone explain this constant current load circuit?

I'm currently a rising junior in EE and I was just wondering if anyone could help explain this circuit for me. The purpose for this is because I need to learn how to build a discharger (constant ...
3
votes
1answer
39 views

how will a connector affect a transmission line?

I am laying out an RS485 driver and read a few design guides which recommend a 120 Ohm termination resistor. This makes sense since the characteristic impedance of twisted pair cables is in the 100 ...
0
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1answer
111 views

What could cause a microcontroller on a board not to accept programming?

EDIT: To summarise - when I take the microcontroller off the board, it works. But when I leave it on the board and try to program it, I cannot. I have designed a PCB and had it fabricated. This PCB ...
1
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0answers
44 views

What causes long-term RTD reading drifts?

I am working with a controller that was designed to read multiple types of inputs including 3 wire RTD signals. In some cases, we have observed the controller suddenly spike up +15 degrees and ...
0
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0answers
65 views

Tight Space Pin Remapping for General IC Controller Socket Design (3d Printer Main Board) [on hold]

I'm currently contemplating a 3d printer main board design... I would like to minimize price and maximize reliability and re usability. Existing boards use a somewhat monolithic architecture; Usually ...
26
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5answers
4k views

Why are GND pads often only connected by four traces? [duplicate]

I have seen this everywhere but cannot figure out why it would make sense to essentially compromise the quality of the ground connection. Is this done for visual reasons? Here is an example:
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1answer
22 views

What could be causing an unreliable output for 3 different IS31FL3731 chips

I have a board that uses the Adafruit breakout of the IS31FL3731 to control 81 illuminated switches. I have some code that runs on an Arduino that should turn all the lights on, but only about half ...
1
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0answers
63 views

Drawing with a triangular aperture in Gerber

So, I`d like to output a rounded equilateral triangle in Gerber format. The first method I tried was to pick a large triangular aperture (%ADD11P,8X3*%, that is) ...
-2
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0answers
31 views

Sinotimer progamable timer relay [duplicate]

Unfortunately it burnt due to power short circuit or another reason. After open the circuit I have found two problems: The resistor acting as a fuse is burned which was wire wound fuse resistor. The ...
0
votes
0answers
74 views

Need help getting started on my first project - Flexible PCB circuit routing [closed]

I am new to electrical engineering so I am trying to explain my project in simple words - please excuse wrong terms, etc. :) The software part is less an issue for me because I know how to write code ...
4
votes
1answer
87 views

Why would I use triangular solder jumper pads?

My PCB layout program of choice - Kicad - has footprints for normal rounded solder jumpers; but also triangular ones. What benefits, if any, do the triangular ones offer? Or is it a purely aesthetic ...
0
votes
1answer
66 views

Distance between UART and I2C bus

I create a board with two bus: UART and I2C. Now I am expanding the connection terminal, which has the following contacts: RX / TX / SDA / SCL / + 5V / GND. The question is, do the I2C and UART buses ...
3
votes
1answer
132 views

Is there any advantage to using multiple tracks in this PCB design?

I'm fairly new to PCB designing, but I'm loving experimenting with it. Currently, I'm trying to develop a simple PWM circuit using MOSFETs to control an RGBW strip, using an Arduino with an integrated ...
1
vote
1answer
27 views

Altium PCB Footprint Component Size Does Not Interpret Text Properly

I have just updated from Altium 17 to Altium 18 and I am seeing a strange behavior where the special string text overrides the the actual size of the text. This special string text size is being ...
2
votes
2answers
53 views

How to extract minimum supply voltage from the datasheets

I am relatively new to electronics and need to know What is the minimum supply voltage (Vcc) for LM1875 and for LF347 and how do I extract it from the datasheets? In LM1875 it is written that the ...
2
votes
3answers
115 views

Why some vias have solder mask and others do not?

Here's an area of a commercial PCB. I'd like to know if the "missing" solder mask is a deliberate choice made by the PCB designer, and if so, why? edit: changed graphic to highlight representative ...
0
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0answers
38 views

Relation between selective soldering and component height

I learned about selective soldering process for through hole soldering. I am not sure if I am able to use selective soldering if my tallest component is on the bottom side of the board. Can you ...
-1
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0answers
33 views

PCB design to determine thermal charecteristics [closed]

I am working on a power distribution unit ánd I need to design a PCB trace to determine the thermal charecteristics. I know Eagle can be used to design a PCB trace but my question is what kind of ...
0
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0answers
63 views

RS485 PCB Design

I'm currently in the process of designing PCBs for my project. There's going to be one larger control board, and 10 daughter boards. The daughter boards will measure the current/voltage of some ...
1
vote
1answer
43 views

Is a higher capacitance rating ok for filtering?

I am newer to electronic design and bought the mpu6050 sensor chip, which the documentation can be found here: https://datasheet.lcsc.com/szlcsc/TDK-InvenSense-MPU-6050_C24112.pdf It says that pin 20 ...
1
vote
1answer
96 views

Designing a PCB with multiple supply voltages

I'm in a process of designing a 2 layer PCB for my device. The device is a master control board, and there will be 10 daughter boards. Various peripherals and things will be connected there: I need ...
0
votes
2answers
27 views

What would prevent me from copying pads (or other components) in Altium?

I'm attempting to copy and paste several components from one Altium PCB to another. I would like to copy and paste all the components all at once, because they are mounting hardware for another PCB, ...
1
vote
2answers
64 views

A small PCB Stack Up for High Speed

I design 2 PCB's. They are connected with a connector. First one is PCB1, has the size of 50cmX10cm , the other one is PCB2 and has the size 2x5 cm. Through this pcbs and connectors some ...
1
vote
1answer
45 views

Altium: how to assign a net class to unconnected pins?

I have PCB with a clearance rule for nets that can be exposed for higher voltages: In the schematic I put a blanket around the area I need to be assigned as higher voltages nets (I called this class "...
0
votes
2answers
55 views

What specs does the “gros condo” (big capacitor) needs to have?

I have a pair of Dynaudio Air 20 at home. Unfortunately, the cable that used to control the speakers via RS232 died. I opened the cable, and saw that it was a customized RS-232 to TTL adapter, but ...
0
votes
1answer
29 views

Altium Designer 16.1 Can't find Pin in Place Menu

I am new to Altium, so this is probably a stupid question. I want to place a pin in a schematic, as described here. But I cannot find pin in any of the menus. No pins anywhere... What am I doing ...
1
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1answer
49 views

Low Profile PCB Connector Identification

There's some connectors on a PCB I would like to make a breakout for, but I'm having trouble identifying the connector type. Could somebody help me identify what type of connector this is, and ...
-1
votes
1answer
126 views

How can i split PCB?

I have a PCB as shown below: My pcb is updated some portion.. I will uploading my updated pcb.. I have specific dimensions to design the PCB. The problem is AC line is passed below the relay ...
1
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2answers
62 views

How can I program an SOC without a hardware kit?

I am new to the production side of electronics. I was wondering if I can directly use a DA14683 to implement a size-constrained project. I have a few queries in mind Is interfacing a SOC similar to ...
10
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3answers
4k views

What are these round pads on the bottom of a PCB?

What are these round pads on the bottom of a PCB marked ScX? I don't think these are test points - this board has some (not in the picture) and they're labelled with TP and the pad size and shape are ...
1
vote
3answers
49 views

Connecting two nets in Eagle

I'm designing a schematic and board in Eagle 9.4.0. I have couple different power nets: signal 5V, power 5V (for servos) and power 8V (from battery). I'd like the power nets to be wider than others, ...
0
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0answers
58 views

Everything seems fine, but SPI Read/Write simply doesn't work. (Hardware-related)

Made a working breadboard Made a working protoboard Printed PCB - same exact schematic and code. Having issues. It appears to be just fine. The SS lines are working from the Pi all the way to the ...
-1
votes
2answers
69 views

In Circuit Tester design

I wanted to create an ICT to check for shorts and validate some of the voltage levels on a PCB that I created, using a jig. I have placed probe points on the desired nets and will be using pogo pins ...
0
votes
1answer
100 views

Unusual behaviour between two seperate electrical circuits in a race-car

simulate this circuit – Schematic created using CircuitLab I have designed and created two systems that are currently present in a small race-car. The first one is a circuit to control the ...
1
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0answers
45 views

Reason for stepped pins on M12 circular connector

I've been looking at M12 circular connectors for a project I'm working on (for example this one, drawing here), and I've noticed that many/all of them have stepped pins that create a 3mm or so offset/...
0
votes
2answers
78 views

How to design an STM32 board with UART over a USB connection?

Sorry if this seems a stupid question but I'm designing a custom PCB based on the STM32F303RE microcontroller and am slightly confused as to how the UART should be connected in the hardware in order ...
2
votes
2answers
217 views

Reduce impedance for power traces of a decoupling Cap when ground planes are not directly under

I am using an SHTC3 temp and humid sensor to send readings using I2C lines to the MCU. Based on the datasheet for SHTC3 to make sure the sensor is reading ambient temp without the interference of the ...
0
votes
2answers
90 views

PCB Crystal holder

I am designing a PCB consisting a microcontroller in which I have to ensure that I have removable crystal . I am looking for a female connector in which I can easily plug/unplug/swap the crystal (...
6
votes
3answers
1k views

Decoupling cap routing on a 4 layer PCB

I would like to place some decoupling caps for an IC. The IC is on the top while the caps will be on the bottom, opposite side. How should I route them: A single VIA that connects the IC pin, power ...
0
votes
1answer
59 views

PCB power connector identification

Can anyone identify the series of connector used for the AC input of this TDK MSA818 PSU from the late '80s? The pin spacing is ~7.3mm (3.65mm if you count the missing pins) which doesn't match any ...
4
votes
8answers
2k views

How can I add “standoffs” to elevate a SMD component above the PCB?

I made a mistake when creating a symbol/footprint for a small (2.0 x 1.6 mm) SMD crystal and didn't notice until the prototypes didn't work. Unfortunately, the boards are tiny and expensive (0.4 mm ...
1
vote
1answer
65 views

Why is the input reflection signal very weak?

I built a PCB filter in Class "Band-pass" with center frequency of 2.4 GHz. The board has two SMA's (input 1 & output 2). S(1,2) looks like this: The frequency is good, However, the attenuation ...
0
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0answers
28 views

Does feedline of through-hole antennas have to be at the bottom?

Does feedline of through-hole antennas have to be at the bottom of the PCB or is it ok to have it on the top? I don't see why it can't be on the top but I read in Taoglas docs that it should be on the ...
1
vote
2answers
45 views

Altium 19 stack manager and Gerber file setup

I have installed Altium Designer 19 recently but I have two problems with this version: First of all, when I open the layer stack manager I can not see "save and load and advance" at bottom. I don't ...