Skip to main content

New answers tagged

1 vote
Accepted

How can i make this idea work in PCB?

The voltage divider should be in parallel with your voltage source, i.e. "across" it. The current sensor should be in series with the source and load.
vir's user avatar
  • 20.3k
1 vote
Accepted

Circuit schema 2 ways WS2812 connect with 1 PCB layout

Your updated schematic would work if "jumpered" correctly: Left-to-right: or Rigth-to-left But I seriously fail to see a benefit of this design, instead of simply "rotating" the ...
Velvet's user avatar
  • 4,501
1 vote

Is a shunt jumper for a power plane jumper a good idea?

You could even use several jumpers for different supply domains going to different parts of the circuit. That could help for problems that are not in the supply but in the circuit, to find out which ...
Jos Bergervoet's user avatar
1 vote

Is a shunt jumper for a power plane jumper a good idea?

Typically during first-round board design I include in schematic/PCB a discrete zero-ohm jumper between the power supply (just after the minimum required output filter caps) and the load net, and size ...
BK303's user avatar
  • 310
3 votes

Is a shunt jumper for a power plane jumper a good idea?

Beats me -- depends what the circuit is, what's on the other side of it. But regardless of that, I can express what possible concerns I would expect, and what alternatives I would consider: Ampacity. ...
Tim Williams's user avatar
  • 39.5k
3 votes

Is a shunt jumper for a power plane jumper a good idea?

It's fine if you are comfortable with adding 50 to 100milliOhms of contact resistance and a small amount of inductance to the rails. I'd leave the caps in.
Voltage Spike's user avatar
  • 84.8k
1 vote

Maximum LEDs on a pin of an AVR Microcontroller

You are correct in that the microcontroller's pin I/O current spec limits how many LEDs you can drive. In general, you should not exceed the datasheet limits given for I(oh) and I(ol) for a single pin,...
hacktastical's user avatar
2 votes

What is wrong in this schematic?

The U1, U4, U8 and U16 devices are all Allegro ...
Chester Gillon's user avatar
2 votes

A basic question about using dielectric material in PCB boards in relation to electric field

Forget about the field lines, they are just a visualizaton of the field; at least personally, I find them when changing through media very confusing, compared to the "simple" idea of the ...
Marcus Müller's user avatar
1 vote

Deciphering workings of a printed circuit board for a night-light

Reason for labelling of F1 Why it is labelled "F1" not "R#", I don't know. It is probably a fusible resistor for protection against overload. I haven't attempted to trace the ...
Chester Gillon's user avatar
3 votes

Deciphering workings of a printed circuit board for a night-light

The usual way is to trace it out; one of the best ways is in a drawing package with layers, for example the open source package Inkscape. You put the top and bottom images lined up (here bottom is ...
jonathanjo's user avatar
4 votes

Deciphering workings of a printed circuit board for a night-light

A capacitive dropper is used to create a low DC voltage. This design is non-isolated, so it should only be used when the circuit can't be touched. https://en.wikipedia.org/wiki/...
Mattman944's user avatar
  • 16.5k
1 vote

Do you know this circuit?

The 2 PNPs form a simple comparator; comparing the emitter voltages. When the 3V3 level is higher than ext_3V3, the right-hand PNP will have a higher VBE than the left-hand one (since the bases are ...
jp314's user avatar
  • 19.4k
4 votes

Custom PCB to make a high-precision, low-current voltage source "fix" drift in a lower-precision, high-current current source

No need for high-side sense, in fact it's better low-side. Other changes are suggested as well: Note the Yokogawa isn't doing much here, and can be discarded. U3 is setting reference. If you need ...
Tim Williams's user avatar
  • 39.5k
0 votes

Turning on a 600W AC motor (PCB, circuit design)

It won't work very well with the driver returned to device common (MT1, BTA26 pin 1). The MOC has to source power from MT2 (pin 2) into G (pin 3). Give or take exact snubber values, this is fine for ...
Tim Williams's user avatar
  • 39.5k
0 votes
Accepted

Turning on a 600W AC motor (PCB, circuit design)

If the BTA26 isn't getting hot it should preform well. Make sure you adjust the snubber for the inductive load, because inductive loads can change the zeroing point and cause issues for the triac.
Voltage Spike's user avatar
  • 84.8k
2 votes

What is the best solution to keeping heavier components on a double-sided PCB while going through second pass reflow?

As a last resort, if the techniques mentioned by V. Spike don't work for you, you can use glue, typically it's red in colour (perhaps for visibility). Here is one supplier, there are others such as ...
Spehro Pefhany's user avatar
2 votes

What is the best solution to keeping heavier components on a double-sided PCB while going through second pass reflow?

Put all heavy parts on one side of board Handsolder heavy parts Use dual temperature solder processes (use a higher temp solder for the one side of the board and a lower temp for the final pass)
Voltage Spike's user avatar
  • 84.8k
1 vote
Accepted

Using MUXs to Address Multiple Devices

So to aswer the question, the best resource how to program that chip is the data sheet. Failing that, it is a very common chip so likely some hobbyists have created blogs or Youtube videos about it, ...
Justme's user avatar
  • 158k
0 votes

How to isolate RS485 (A and B) from existing transceiver? Check attached circuit diagram, is it correct?

This will be hard. You cannot know when either side has enabled transmitter and will soon transmit something on bus, you only see when something gets transmitted. Perhaps if you know about the ...
Justme's user avatar
  • 158k
2 votes

How to isolate RS485 (A and B) from existing transceiver? Check attached circuit diagram, is it correct?

If I've understood your goal, you have a controller device which is half-duplex RS-485 (on the left), and a slave device, similar, on the right. The controller is not isolated, and you want it to be. ...
jonathanjo's user avatar
1 vote

LSM303AGR burnt, help find the schematic error

The footprint and pins look good. One problem I see is there are no vias that go to ground for C20, C19 and C18. I don't see any traces routed out from the ground pad or vias in pad. This could be ...
Voltage Spike's user avatar
  • 84.8k
0 votes

DDR4 Routing Consideration

The first BO1 is probably the trace and or processor pin impedance (make sure you include the package trace length in DDR4 calculations if the device package is not length matched). The BO2 could be ...
Voltage Spike's user avatar
  • 84.8k
6 votes
Accepted

Schematic component

No and Yes. You have circled both a fuse F1 and a ferrite bead FB16. The wavy component is the fuse, rated 5A. The ring with wire through is the ferrite bead. Ferrite beads are typically rate d at ...
Justme's user avatar
  • 158k
2 votes

Schematic component

1- "The wave" is F1, it is a fuse, and it's rated at 5A. 2- Yes, it's for use with an external power source. 3- D44 is not a shcottky diode; it's a TVS diode (not zener), and its use is ESD ...
mocal_381's user avatar
3 votes

Schematic component

The wave part is the symbol for a fuse. It is rated for 5 A and is in a 1210 surface-mount package. To the right of it is a ferrite bead. DNP stands for Do Not Populate. It might be something left ...
AnalogKid's user avatar
  • 21.3k
1 vote

PCB Silkscreen Marking

No one checks designators, there's no like universal regulatory process or anything -- at most, in-house standards apply, or only what is dictated by contract terms. There are standards, such as ANSI-...
Tim Williams's user avatar
  • 39.5k
8 votes
Accepted

Why does IPC 2221 require so much more spacing at elevation?

It comes from the Paschen's Law. The following graph is a Paschen curve taken from this research. The graph may look a bit awkward to make a conclusion as "required clearance increases with ...
Rohat Kılıç's user avatar
4 votes

Why does IPC 2221 require so much more spacing at elevation?

It's more of a one (or two, in this case) size fits all strategy. If you don't want to deal with calculating the exact factor for the altitude at which you'll be operating, then the values given will ...
vir's user avatar
  • 20.3k
1 vote

Will such a scheme work correctly with ATmega328PB?

The accepted answer provides general suggestions on styling and common norms on PCB design but never point out the mistakes on the schematic. I see at least two mistakes. CC1 and CC2 on Type C USB ...
hcheung's user avatar
  • 301
5 votes

Attaching foam to the bottom of a PCB

PCB pillars are a purpose designed tool for the job: While the foam that comes on them is self adhesive, if you don't remove the backing paper they're quite usable as a movable soft contact with the ...
user1908704's user avatar
0 votes
Accepted

Confused about layout guidelines for TPS63710 buck converter

It's not much different than having a bypass cap on a normal logic IC with one supply and one ground pin. Or rather, a logic IC with built-in regulator and the logic that uses the output of the ...
Justme's user avatar
  • 158k
4 votes

Attaching foam to the bottom of a PCB

Unless the desk is perfectly flat with nothing on it, and you carve out bits of the foam where the through-hole component legs are, a layer of foam across the whole board is unlikely to sit flat on a ...
Tom Carpenter's user avatar
2 votes

Attaching foam to the bottom of a PCB

My answer would be very much the one of GodJihyo, except it you get your PCB manufactured industrially, you might give a try at getting a 2nd "PCB", except with just holes for standoffs/...
user1532080's user avatar
4 votes

Attaching foam to the bottom of a PCB

You might look at using something like hobby wood, thin wood sheets typically made of basswood. You could have mounting holes in each corner of your circuit boards and maybe one or two in the middle, ...
GodJihyo's user avatar
  • 24.9k
1 vote

74HC595 behaves randomly, need help with my circuit

Each time I start it, the output values are all random until it settles on a number It sounds like you are seeing the register powering up in an undefined state, which is normal. There's no guarantee ...
Simon Fitch's user avatar
  • 38.7k
2 votes

Attaching foam to the bottom of a PCB

Maybe consider 3D printing a board holder that protects the bottom and keeps things from getting scratched. I do that sometimes when a board is going to be handled a lot (e.g. for firmware or HDL ...
Spehro Pefhany's user avatar
0 votes
Accepted

74HC595 behaves randomly, need help with my circuit

I would like to thank all of those who tried helping me troubleshoot this problem. Unfortunately, none of the answers worked. I therefore used the remaining pins of the ESP32 to drive the K155NA1 ...
TakeHere's user avatar
7 votes

Attaching foam to the bottom of a PCB

Unless there are heat producing or high power devices that are counting on airflow for heat rejection, a closed-cell flame-retardant, adhesive-backed foam would work. Knowing students however, ...
vir's user avatar
  • 20.3k
2 votes
Accepted

PCB trace impedance infinite equivalent impedance of RLC model

However, if we connect the same circuit one after the other, shouldn't the impedance decrease? The impedance of a section of transmission line is calculated assuming it is loaded with another ...
Andy aka's user avatar
  • 465k
2 votes

74HC595 behaves randomly, need help with my circuit

Actually it's the other way around, I would not expect the breadboard prototype to work well either. The breadboard even connects LEDs directly to HC595 output pins which may lead to burnt-up LEDs or ...
Justme's user avatar
  • 158k
0 votes

74HC595 behaves randomly, need help with my circuit

I see two possible issues here: You should have at least 100nF (0.1uF) capacitors between the positive supply pins of 74HC595 and K155NA1, and their GND pins. They shoud be as close as possible to ...
Edin Fifić's user avatar
  • 5,481
0 votes

Altium Polygon Custom Queries keep disappearing

Okay, so I figured it out, and I'm adding this answer in case anyone come across this issue in the future. When using Query's in Alitum, you are able to use Logic notation, such as And, Or, Not. For ...
Jay's user avatar
  • 1,195
4 votes
Accepted

Will such a scheme work correctly with ATmega328PB?

Firstly, I suggest working on your diagram. A hard-to-read diagram will almost inevitably have mistakes. Specifically about the circuit: Where are the decoupling caps? How does ...
jonathanjo's user avatar
1 vote
Accepted

PCB microprocessor 16MHz oscillator layout feedback

The schematics are now correct regarding the crystal not being grounded from one leg. But AVRs do not need a resistor between the crystal pins, and even if they did, the 10 ohms would be completely ...
Justme's user avatar
  • 158k
4 votes

Unexpected Loss In Signal Integrity

I also didn't add a ground plane because I didn't know how to do it at that time. That's the primary source of the problem. Even though the display is connected directly to the board, the signal has ...
Kuba hasn't forgotten Monica's user avatar
1 vote
Accepted

What is the return current path for inner layer routed trace (six layer PCB)

Switching between layer 1 and layer six, here stitching vias are necessary as you have already done. Routing on layer 3 could also be OK as long as you keep in mind how the layer 4 (PWR) is routed. If ...
Tyassin's user avatar
  • 159
0 votes

Measuring Ethernet Impedance

I suspect there is a signal integrity issue that is causing the ethernet to work intermittently, but how do I go about proving it? First and foremost - there is not differential pair or impedance for ...
Voltage Spike's user avatar
  • 84.8k
8 votes

KiCAD symbols for JST connectors

There are hundreds of "generic" connector symbols in KiCAD. Choose one that matches the pin numbers on the footprint and use it in your schematic. Then allocate the footprint to the symbol ...
Andy aka's user avatar
  • 465k
1 vote

PCB layout for 16 MHz crystal oscillator

The whole reset/crystal circuitry is wrong so it won't even work. Please look at data sheet or hardware getting started guide appnote or even look at the Arduino board schematics you seem to have ...
Justme's user avatar
  • 158k

Top 50 recent answers are included