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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48 views

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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4answers
77 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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60 views

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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20 views

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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1answer
73 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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64 views

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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1answer
419 views

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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1answer
68 views

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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37 views

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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1answer
843 views

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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158 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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3answers
2k 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 ...
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1answer
65 views

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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52 views

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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1answer
41 views

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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1answer
300 views

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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512 views

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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26 views

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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25 views

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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3answers
154 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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3answers
544 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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1answer
166 views

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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1answer
95 views

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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2answers
120 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 ...
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449 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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5k views

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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194 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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525 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?
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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 ...
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1answer
2k 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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2answers
533 views

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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3answers
1k views

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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1answer
666 views

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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84 views

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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1answer
3k views

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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1answer
1k views

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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1answer
1k views

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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2answers
262 views

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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1answer
400 views

What type of electronics soldering is this soldering flux used for?

I usually use rosin flux for soldering or one with rosin core if the solder refuses to stick. I recently found this Goot BS-15 flux, but it says not applicable to PC boards. The label says hobby use ...
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1answer
523 views

Residual flux conductivity on PCBs causing problems?

The question here is how much flux remains on boards under normal manufacturing conditions, how conductive is it, and does the conductivity change with humidity and temperature. I know that for ...
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0answers
94 views

What is the internal linkage flux of a wire with radius a(shaped like a cylinder)

How can we clarify that the relation between linkage flux an flux in a cylinder shaped wire is \$ d\lambda=\frac{x^2}{a^2}\ d\phi \$?can we illustrate this by electromagnetic formula?I think I would ...
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1answer
1k views

Mosfet failure in DC-DC switching converter: root cause analysis and countermeasures

I'm dealing with a pilot project which involves several units on the field (around 15 units) powered by a control card which needs to drive two resistive loads in DC in the range of 13-5 VDC. Each of ...
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3answers
317 views

Soldering question

Yesterday I soldered quite some things, but I'm still a beginner. I noticed that sometimes it happened that sometimes I use to much solder. When trying to remove it, I heat the pin with solder so it ...
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2answers
2k views

Bismuth or Indium solder - how do they compare?

In my previous question I focused on lead-based solder alloys (see Best solder wire - Sn63Pb37 vs Sn60Pb40 vs ...?). Some of you brought new exciting solder alloys to my attention. The two most ...
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9answers
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Is acetone or isopropyl alcohol better for removing rosin flux?

For removing rosin flux from my board, should I use Acetone or Isopropyl Alcohol? I need an easily available solvent.
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1answer
593 views

Best Solder & flux for jewellery made with copper foil? [closed]

I want to make some glass jewellery with copper foil, but obviously can't use my usual lead solder that i use for my stained glass art, which is the best lead-free solder and what flux would it need. ...
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2answers
3k views

I need help for soldering. Is this good flux for use on PCB/Electronics?

this is a specific question to a product for soldering. I am a newbie to soldering so be kind. To be honest I was trying to learn soldering and watched videos and read some. But in germany there ...
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41k views

Solder Paste vs Solder Flux

I bought a "Solder Paste". It is in quote because I'm not really sure if it's a Solder Paste itself. I researched about what Solder Paste is and, by definition, is defined as a mixture of small ...
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3answers
709 views

Stainless steel soldering

Was wandering whether anyone could suggest how to solder stainless steel. I know hydrochloric acid flux is suggested to remove oxidation. Anyone could suggest a supplier in UK or who would be able to ...
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2answers
393 views

Hakko FX-888D Iron Issue

I just got a new Hakko 888D for Christmas. I have used it a bit since then, and I'm using the wet sponge, brass sponge, and some RadioShack tip cleaner to maintain the tip quality. The issue I am ...