Questions tagged [flux]

Refers to flux chemicals used in soldering. Use the magnetic-flux tag when referring to magnetic field changes.

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Making a DIY wind generator for kid's project. How can we improve it?

My boy wants to make a wind generator and we have a 3D printer. We have decided to go with an axial flux style 140mm diameter with 12 iron free coils (4 per phase) so it can turn easily. Without gears,...
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1 answer
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Which flux type to use when soldering stranded wires that will be conformal coated?

I am doing a hobby project where I am weaving stranded wire through vias on the PCB. There is a matching copper trace and solder mask under the stranded wire. The stranded wire is soldered onto the ...
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3 answers
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Soldering wires to non-plated pins?

Product: QSB35024S24 Images: An image of the product I'm working on. The image depicts pins -Vo,+Vo,-Vin,+Vin- these four pins are the troublemakers. A sample image of the product as it was soldered ...
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3 votes
2 answers
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Storage of liquid flux

I have recently acquired a 1 L bottle of liquid flux. I only realised upon receipt that it is quite flammable and that I may not be able to provide the proper storage conditions. For now I have just ...
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1 answer
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What happens to the permanent magnet flux of this synchronous motor?

Considering a synchronous motor with permanent magnets (1 pair) If there is a synchronous motor with permanent magnets and I was given the initial permanent magnet flux Y_mp = e0(at 15 rps) / w (at 15 ...
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Flux to lower solder ball melting point

Is there any such flux? I find the balls on BGAs very hard on my home made oven. From what I gather, mixing up solder types in order to lower the melting point is not the best idea, especially when ...
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5 votes
2 answers
933 views

Recovering from failure to clean off solder flux

I'm currently building a prototype device at work, that involves a QFN-64 0.5mm pitch IC (a PIC microcontroller) soldered onto a SchmartBoard|ez prototyping board. The SchmartBoard instructions call ...
2 votes
0 answers
54 views

How does mutual flux in a synchronous generator remain constant like in a transformer?

Given is the flux per pole of of a synchronous generator 1)Is it field/rotor flux per pole ? 2)The generated emf per phase is given by E=4.44Nfφ where φ is the flux per pole But from transformers, we ...
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2 answers
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Possible Contradiction in N87 ferrite material μa vs B graph

Why does this graph description (of N87 material) states ^B =< 0.25mT (which is peak flux density), even though horizontal axis goes up to 0.40T? Is the horizontal axis in tesla peak-to-peak? Is it ...
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How can the magentic flux be determined in a transformer with airgap?

I am planning to conduct chemical reactions in an AC magnetic field at 60Hz. The magnetic setup is made of two 1.4kW microwave transformers with HV coils and Iron I-cores removed. Then the two ...
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1 answer
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Why it can be asserted that the bottom plate takes the highest potential and the top plates takes the lowest of the capacitor?

The ideal parallel capacitor has been filled with 2 dielectrics as shown in the above diagram. $$ V_{1} :=\text{potential at the top plate} $$ $$ V_{2} :=\text{potential at the bottom plate} $$ $$...
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1 answer
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Flux for removing LGA socket

I have been looking into the stackexchange searchbar and also I have been searching for a day or two globally, even the "similiar dialog on this website" when I was creating this post. I ...
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Coiling ac wire around iron rod bad or good?

I have around 4-5 meter excess wire length on extension board to power my computer. Power consumption is around max 500 watt. I know there are probably 2 more thread on same topic. But they mostly ...
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4 answers
585 views

Using and maintaining lower end soldering iron tips without destroying them

I bought a low end soldering iron of eBay - it was advertised as a "15 in 1 Soldering Iron Kit", and was advertised as temperature adjustable. It has a dial to adjust the temperature with ...
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1 vote
2 answers
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Why does an additional primary current exist in a loaded transformer?

I think this has something to do with Faraday's Law but like, I don't get why having a secondary current produces a antiphase secondary current at the same instant. Not all currents produce a direct ...
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Are there other quantities besides voltage and current that can be expressed as instantaneous values in AC circuits?

https://www.electrical4u.com/emf-equation-of-transformer-turns-voltage-transformation-ratio-of-transformer/ I got really confused when all of a sudden they treated flux with the time domain equation ...
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1 answer
343 views

Reducing equivalent self inductance of an inductor

Let's say I have a coil of N turns and it is wound on a rectangular core and when we connect a voltage source through both terminal of coil flux is generated in core , now I wanted to reduce that flux ...
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How do I actually verify that a flux is made for electronics and not plumbing?

After seeing a question about soldering flux and in particular flux paste which I'm interested in trying, I was reminded that there is a lot of confusion and scare about solder flux. I'm one of the ...
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4 votes
1 answer
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Are soldering fluxes safe to touch?

I'm new to PCB soldering. I just bought a cheap soldering iron, solder wire and flux to try something. I have no previous experience with soldering. I'm well aware of the potential risks of prolonged ...
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3 votes
1 answer
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What is "activity" in solder flux?

I'm trying to select a solder flux and so many references (and one or two SE questions) discuss the types and differences. They mention "activity", such as "Rosin Activated (RA) flux ...
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Storing liquid soldering flux long-term. Is it light sensitive?

Is soldering flux known to be light sensitive? I got a big jug but the big jug it arrived in is deformed and doesn't look like it's going to hold so I am going to transfer it over to some bottles for ...
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4 votes
1 answer
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Why does PCB copper surface oxidize when I apply flux on its surface?

I had to create a printed circuit board for a project, using the home method (PCB developer solution, iron chloride.) At first, after the PCB was etched, I cleaned it very well using paper towels and ...
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2 answers
808 views

Why is flux in field winding constant in DC shunt motor, but not series motor?

As titled, why is the field winding constant in DC shunt motor, but not series motor?
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3 answers
5k views

Substitute for solder wire and flux [closed]

So I am trying to get started soldering, but I was wondering if there was any common household component that I could somehow take out the soldering wire or flux. Although any alternatives will be ...
1 vote
1 answer
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Current in delta connection

I know how to calculate current in delta connection but just for knowledge purpose I wanted to know from basics why this method(in image) of calculating phase and line current is completely wrong ...
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Jumping ring demonstration

In demonstration of jumping ring if we assume dc source connected to solenoid, according to most of books, when we place a metallic ring over the solenoid and as soon as we turned on current, due to ...
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1 answer
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Find the flux leaving the surface of the sphere: What will the position of line charges look like diagrammatically?

I am not able to understand how the two uniform line charges will look like in space. It would be of great help if someone could draw the uniform line charges in cartesian coordinates and upload it ...
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1 answer
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Soldering paste or flux

There are a number of materials on the market that help with soldering, prevent oxidation. someone says flux, someone says soldering paste also someone says flux and soldering paste are same. ...
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1 vote
2 answers
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What is this white stuff on the solder of this PCB?

These photos were taken from a new-in-box 16kB memory expander for a Timex Sinclair 1000 computer. As far as I'm aware, it was never used. The box was made of thin cardboard with a two part styrofoam ...
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1 answer
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What affects the current ratings on constant torque pole changing motors?

Two different motors, one is rated 1.49A on slow speed configuration and 1.43A on high speed. The other motor is rated 6.09A on slow speed and 6.99A on high speed. These are constant torque pole ...
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1 answer
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Mean Free Path of Magnetic Core

I don't understand how they got the mean free paths (ls) of each leg. I know that I should be calculating the longest + the shortest paths and divide them by two, but I don't know HOW I should be ...
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2 votes
3 answers
264 views

Transformer’s Flux and Back-EMF

I know that transformer is a constant flux device but there is one point I don't understand. As you know, when secondary of transformer is connected to a load, current starts to flow. This current ...
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5 votes
3 answers
802 views

Clean vs no-clean for high voltage circuit

I have a board that has fairly high working voltages up to 100V with small clearances down to 12 mil between the high voltage and ground or low voltage nets. This is unavoidable because the whole ...
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0 votes
1 answer
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Relationship of Slip and Angle Between Rotor and Stator Flux for Induction Motor

I know how slip and flux angle individually affect torque of induction motors but I can't understand the relationship between slip and flux angle in terms of torque. Do they both have different effect ...
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1 answer
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solder wire makes solid & glassy residue

I know using flux makes some residue which makes unwanted contacts between components pins. I dont have any washing liquid or spray to remove it so i simply decided to not use them. But my solder ...
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2 answers
167 views

A contradiction regarding flux conservation

Consider a simple circuit Initially switch S was opened till steady state is reached and then it was closed. My understanding regarding inductors is that you can't have a SUDDEN change in current ...
3 votes
2 answers
959 views

What would be the consequence of the inductor saturating?

The following is a section from a book where it is talking about decoupling by LRC at supply terminals. I highlighted the sentence where I didnt understand: I read that if an inductor has an iron ...
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4 answers
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Beginner Question - Solder won't stick to a certain wire

I am trying to tin some wires as they won't stick to the IC pins that I'm soldering them to. The problem I am having is that the solder won't stick to the wire. My iron is fine as can solder other ...
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1 answer
238 views

How does flux change polarity in full bridge SMPS transformer?

Take a full bridge switching circuit connected to the primary of a transformer. Assume: No load on secondary. Voltage into full bridge is DC. Duty cycle of switching is 50%. At t = 0, full bridge ...
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1 answer
678 views

What type of mask to be used in lead free soldering?

Is it safe to use mask for lead free soldering in solar string soldering? What type of mask to be used? What is the difference between lead based and lead free flux?
-4 votes
1 answer
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Maximum and Minimum flux in a coil [closed]

A coil of 100 turns and a diameter of 3.18cm is mounted on an axle through a diameter and is place in a uniform magnetic field, where the flux density is 0.01T, in such a manner that the axle is ...
9 votes
1 answer
3k views

What happens if a solder joint cools before all the flux has evaporated?

Sometimes, when soldering, I see little bubbles come out of the hot joint. Presumably, this is the flux evaporating and escaping as a gas. What happens if I remove the iron and let the joint cool ...
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3 votes
2 answers
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Trying to choose a flux pen for my lab - Stannol X32 vs. X33S, what's the difference?

Dear fellow users of Electronics StackExchange, I'm in the process of trying to upgrade my electronics lab to be able to comfortably drag-solder dense SMD packages (SO's and PLCC's) and I'm wondering ...
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Confusion regarding eddy current losses

I have been taught in my machine's class that eddy current losses are proportional to the square of frequency*flux density, this seemed so fair that I never questioned this. But my machine design book ...
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1 vote
1 answer
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Why is the Exciting Current zero in an ideal transformer?

An ideal transformer having infinite permeability core is supposed to have zero exciting current. An ideal transformer has infinite permeability core, which means that all the flux in the universe ...
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Possible causes of loss of electrical contact between PCB traces and male USB Type A connector pins soldered to PCB?

I have a problem that I've been embarrassingly working on for months and unable to completely solve. I'm a hobbyist and I have a simple PCB with a male USB Type A connector soldered to it: some of my ...
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1 vote
1 answer
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Why does speed of DC motor increase when flux is reduced?

I understand that from KVL e = v -IaRa e=k(flux)speed speed=(constant)*(V-IaRa)/flux But physically what causes the speed to increase? What force causes the rotor to accelerate? In fact, ...
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2 votes
1 answer
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Should I spray some flux on my board before putting it in the reflow oven?

I am using Tin-Lead solderpaste to make my prototype circuits. This is the exact solder paste: ALPHA OM-5100 (https://alphaassembly.com/Products/Solder-Paste/OM-5100)     ...
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7 votes
1 answer
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Effects of no-clean flux or RMA flux residue on signals

I keep on hearing that no-clean solder paste or flux is bad for analog or digital signals because it makes analog signals "noisy" and promotes cross talk on digital signals. Like this claim:...
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soldering a 12V plug cathode

I cant seem to properly solder a stranded wire to that cathode terminal. Checked the answer https://electronics.stackexchange.com/a/90605/35737 - fluxing it did not help and solder does not adhere to ...
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