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Questions tagged [polarity]

Polarity is a conceptual entity. Pole means a direction. However, an object is called as "having polarity" or "having specific polarity" means a preference to a differential-behavior of something in forward and backward direction.

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How does USB Type C handle reverse polarity

The new USB Type C connector doesn't have a physical reverse polarity protection anymore. You can plug it in any way you want on both ends, there is also no A and B end anymore, it's all the same. So ...
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3answers
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Why do we use polarized capacitors?

I want to know if the polarized capacitor has some advantage that they are used in some circuits? For example, in a schematic of the BISS001 PIR controller IC, in some places, a polarized capacitor ...
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4answers
85k views

In an NMOS, does current flow from source to drain or vice-versa?

In an NMOS, does current flow from source to drain or vice-versa? This Wikipedia page is confusing me: http://en.wikipedia.org/wiki/MOSFET The above image confuses me. For the N-channel, it shows ...
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2answers
33k views

How do I decide what capacitor to use in a circuit?

I am using a voltage regulator, and to get cleaner power, the datasheet recommends using a 0.33uF capacitor. However, it doesn't say what type it wants. Stupidly, I ...
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1answer
8k views

Reverse polarity protection

I read somewhere that this can be used for the reverse polarity protection in the circuit. But I am quite confused with its operation. Can somebody help me with this. simulate this circuit – ...
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2answers
20k views

Does MOSFET let current flow through source to drain as it allows it from drain to source?

Does a MOSFET allow current flow in reverse direction (i.e.; from source to drain)? I made a Google search, but couldn't find a clear statement about this matter. I have found this similar question, ...
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3answers
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What does the radiation from an antenna look like?

Just out of curiosity, I searched for antenna on Google Images, and what usually shows is something like this. So I really thought that an antenna radiates in a circular and equal pattern. But as I ...
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4answers
8k views

Does an over voltage, over current and reverse polarity protection IC exist?

I'm designing a circuit that has the following protection requirements: Reverse polarity Over voltage (60v max) Over current (approx 1A) There's quite a large input voltage range, 10v to 60v. 48v ...
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1answer
9k views

What are the disadvantages of using a diode bridge for DC polarity?

As far as I understand, diode bridges are mainly used to convert AC into DC, but one can also use them just to ensure an expected DC output polarity for arbitrary DC input polarity. I have some small ...
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5answers
2k views

Why don't more devices incorporate full-wave rectifiers as reverse polarity protection?

Recently, I was introduced to the idea of using a full-wave rectifier, in order to protect against reverse polarity damage in DC devices. I hadn't even considered using a rectifier in an already DC ...
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3answers
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SMD LED polarity marking: is the cathode marking standardized?

SMD LEDs normally have some kind of marking like the following image from here indicates: The site states The CATHODE lead is always the lead to be identified with ALL LEDs, including surface-...
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2answers
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Are peltier elements polarized?

I'm looking to add a peltier element to one of my projects. However, I want to sometimes heat and sometimes cool, depending on the ambient temperatures on both sides of the element. Image ...
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2answers
2k views

Why does this two terminal inductor have a polarity?

The Murata LQP03TN2N0C02D 2nH 0201 size inductor apparently has a polarity marking on the package: I don't see anything on the data sheet that suggests there's a difference installing it in a circuit ...
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3answers
10k views

How can the capacitor be connected in reverse polarity?

If the polarity changes every time the AC switches, then why doesn't the capacitor explode?
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2answers
46k views

Why is the negative contact in a battery bay always the side with some sort of spring?

Is this just purely convention, or is there some kind of technical reason behind it?
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3answers
21k views

Is a Schottky diode appropriate for reverse polarity protection?

To narrow the focus a bit from an earlier question: Is a Schottky diode appropriate for reverse polarity protection? I'd like to prevent mishaps from a user connecting DC power in reverse, but I'd ...
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8answers
12k views

AC polarity detection

How can I detect AC 'reverse polarity' (single phase) (without the use of ground/earth) and drive a led when the polarity is reversed? It should at least detect 230 VAC but it would be cool/...
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2answers
6k views

Reverse polarity protection - PMOS vs Schottkey diode

I have a circuit running from 2 AA cells in series, meaning I get 3.0V when fresh (or 2.4V if NIMH cells) and it goes down to 2.0V, that's when my circuit cannot function anymore (no DC/DC onboard). ...
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5answers
65k views

What to do when a device doesn't specify it's DC polarity?

This is probably a very simple question but.. I've been trying to find replacement AC->DC adapters for various electronics around the house, but I ran into one which doesn't list its polarity. It ...
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4answers
9k views

Aren't non-polarized plugs a little dangerous? Why still use them?

Sorry if there is an answer for this kind of question somewhere. I can't find it anywhere. Take a look at obvious toaster example: If you live in Europe and have non-polarized plug and a toaster (a ...
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2answers
276 views

Reverse voltage protection for Analog Devices’ family of protection controllers

After going through several datasheets for devices from "Analog Devices’ family of high voltage surge stoppers, overvoltage protection, overcurrent protection, and circuit breaker ICs", I found that ...
6
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2answers
1k views

Electrically switching between horizontal and vertical light polarization

I would like to be able to electrically switch between horizontal and vertical light polarization. This polarization filter is supposed to be portable attachment running on a battery in front of a ...
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6answers
1k views

Determining the correct polarity of a supposedly wrong polarized capacitor

I'm fixing an audio interface (Scarlett) that was behaving poorly and found a likely culprit - a bulging capacitor. However, it appears to be soldered on the board backwards (based on the `screen on ...
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1answer
4k views

Packaging polarity indication of a supercapacitor (polarity indicated by arrows)

I obtained some supercaps from an auction site. As is often the case for low cost components from such sources, these do not have supplied data and such branding as there is does not appear traceable. ...
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2answers
4k views

What direction to place electrolytic caps for AC coupling?

If using polarised electrolytic caps in an amplifier circuit as shown below, Does it matter which way round I place the caps? If so, why?
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4answers
11k views

Confusion about dot convention in an ideal transformer

I am confused about voltage polarity and current direction in transformers , for example the equivalent circuit of the ideal transformer in figure(a) the instantaneous voltage polarity of the ...
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3answers
982 views

LED anvil and post are reversed!

Typically, through-hole LEDs seem to have the cathode (-) side connected to the "anvil" and the annode (+) connected to the "post" (see diagram below). ...But I now have in front of me an LED that ...
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7answers
12k views

How to memorize a diode's polarity in symbol? (self-answered)

How to memorize a diode's polarity, such as anode and cathode in symbol?
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2answers
4k views

Can current flow both ways through a transistor?

Last night I was experimenting with and motors and transistors. I was testing out NPN and PNP transistors to learn more about how they work and how I can use microcontrollers to control the speed with ...
4
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2answers
5k views

Reverse polarity protection idea

I'm thinking about making a reverse polarity protection for a project, and I've came up with this idea: simulate this circuit – Schematic created using CircuitLab I think that if I reverse the ...
4
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2answers
2k views

Which symbol to use for polarized capacitor?

Ok guys, this has been driving me crazy and I would love an absolute universal answer (even though I know there are disputes)... Which symbol should I use for a polarized capacitor? At school they ...
4
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1answer
217 views

help understanding this reverse polarity protection circuit

Going through LT4363 evaluation kit DC2062A-B (schematic here), I came across a reverse protection circuitry that protects downstream components from reverse transients and reverse DC voltage: In ...
4
votes
1answer
855 views

Power line protection: overvoltage, ESD, voltage polarity

We are designing an industrial control board. The input voltage of the board is +12V, ground and -12V. Our previous design does not include any power protection and now I want to add over voltage and ...
4
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1answer
2k views

Are Supercapacitors Polarized

There seems to be conflicting information on the internet. Are super capacitors polarized? For instance, could you charge them and then suddenly invert their polarity (à la charge pump)?
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2answers
151 views

Can the electron source be known as the anode in one place and the cathode in another?

It is my understanding that in a Galvanic or electrolytic cell the electrode from which the electrons flow is known as the anode. Yet it is also my understanding that in a vacuum tube the electron ...
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2answers
839 views

Do DC/DC converters provide reverse polarity protection?

I plan on using a TPS63061 as DC/DC to get a steady 5V from 4xAA batteries. The data sheet says: 8.3.4 Undervoltage Lockout An undervoltage lockout function prevents device start-up if the ...
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3answers
62k views

Change Direction of 12v DC Motor Rotation using Relay

I want to make a circuit to change 12 Volt DC Motor direction and move some thing between two points. Using Relay or some basic limit switches.Like this Image. I got a Circuit As i want... AUTOMATIC ...
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1answer
168 views

Is this capacitor polarized?

I recovered a few capacitors of this style from an old cassette player. As far as I can tell, it seems like Mylar film, but the “100⊖” marking has me wondering. Is this some peculiar shaped tantalum ...
3
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1answer
632 views

astable multivibrator: capacitor polarization

Looking at this circuit, I'm wondering if the capacitor polarization "+" is correctly draw. Assuming T2 is in cut, T1 is on, left capacitor will have a 0.7v in its right side (connected to T1 emitter) ...
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3answers
3k views

What is an electrode?

According to wiki, an electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte or a vacuum). Examples of electrodes are the ...
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2answers
14k views

Circuit to reverse polarity

I am doing a project on a door shutter opener where there are two states or signal I pass into the circuit: 0V: Door shutter closed 5V: Door shutter opens. I plan to accomplish this via motor ...
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3answers
6k views

How do I check polarity on loudspeaker?

How do I check the polarity on a loudspeaker? I have an 8 ohm 2 inch speaker with no wires soldered into it and the terminals have no markings. How do I know which of the two terminals is positive ...
3
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2answers
3k views

Why are leads from the negative terminal considered grounds?

I'm using a 9V battery with a 5v regulator as a power supply. What I can't grasp is why I place the regulator in the (+) lead of the battery. If electricity is electrons flowing, and the excess ...
3
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2answers
719 views

Does my device need reverse polarity protection?

I'm developing a device with changeable AAA batteries running at 3V. Since the end user can change the batteries there is a chance they may be put in the wrong way around. The circuit basically ...
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2answers
454 views

Does guitar pickup absolute polarity matter?

I have a Telecaster which has a phase issue in the middle position, because the bridge pickup is wired backwards (the hot output to the ground). This hot grounded output is also used to ground the ...
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1answer
2k views

Help designing an inverse polarity and overload (crowbar) protection circuit

There are some great resources on the internet and on this site about designing various protection (crowbar) circuits. For example, Leon's answer to a general circuit protection question. I'm looking ...
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2answers
349 views

What is the polarity of this barrel plug with a double circle?

Related but doesn't answer my specific icon: How to tell polarity expected of a DC barrel jack? I have a dell laptop barral plug adapter, and I can't tell from the graphic whether the tip is positive ...
2
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2answers
1k views

DC Motor as DC Generator + Output Polarity Switcher

I am working on a hobby circuit. And got a quick question. I am using regular mini DC Motor as DC Generator. If the motor is rotated one side it generates few volts. If the motor is rotated in ...
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6answers
943 views

Why plug is polarized in the US? What are the benefits?

I could not get a good hold of it, I searched online quite a bit. This must have to do with safety but then non-polarized switches are used through out the world with no issues are risks, so my ...
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1answer
8k views

Troubleshooting why Powerbank Doesn't Charge Cell Phone [closed]

I have powerbank that provides 5v (presumably regulated) power, as typical of most usb interface powerbanks. I have been trying out my powerbank with different phones. It works on all except one. I ...