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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46 views

Invert polarity with DPDT relay

I'm trying to wire a 12v DC motor to a DPDT switch so I can control the spin direction (by inverting the polarity) it uses two digital pins, one of them to set the direction of the motor and another ...
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452 views

Electromagnet Polarity Reversal Doesn't Matter?

I am working on an engineering design project for school which uses the electromagnet linked below to "lock" a door. The problem is that the electromagnet remains energized or magnetized even after ...
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353 views

What happens if I change the polarity of the battery?

Suppose if i charge a capacitor. Now if I reverse the polarity of the battery, how much is the heat produce during that process? My book says as change in energy = 0 (in capacitor) therefore heat ...
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106 views

How can a battery get reverse charged? (other than by being charged backwards)

I have an old lead-acid car battery that got taken out of my car by AAA 5-10 years ago when it died during a cold winter. I stashed the battery away and forgot about it. Recently I dusted it off and ...
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24 views

Driving piezo scanner tubes using the driven internal electrode configuration

I'm planning on doing a project involving a piezo tube scanner (PTS). The PTS will be used for 3 axis manipulation of a sharp needle. PiezoDrive has a few scanners and some info on how to use them. ...
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High voltage power supply polarity for X-ray tube application

High voltage power supplies (HVPS) in the range 100 to 200 kV are used for working with X-ray tube. Some HVPS produce negative output voltage or even bipolar output including negative and positive ...
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4answers
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Voltage induced accross an inductor, conceptual confusions

simulate this circuit – Schematic created using CircuitLab OK, I always have a hard time to understand inductors. Now, I do know that inductors will not let current through them to change ...
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29 views

LTC7001 Mosfet Driver is not working because of DPDT Relay

I am using a mosfet driver(LTC7001) to drive a mosfet. The mosfet is conducting 28 V continously which means its driver is always open. In a step I must reverse polarity of load by using a DPDT relay....
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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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45 views

Finding out capacitor polarity on pcb

I made the quintessential newbie mistake: I removed 2 capacitors (CF07/CF08) without noting down the original lead position. The interesting part is that the schematic (attached) seems to convey that ...
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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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106 views

Capacitor put the wrong way by manufacturer - is this on purpose or is this a problem?

I am about to change the electrolytic capacitors of a Soviet Selena radio from 1988. I noticed that a few of the capacitors are put with the oposite polarization in respect to the board, e.g. this one ...
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Can I use this DPDT relay with this circuit? If so, which wires connect to what terminals?

I'm following this tutorial to wire an automatic chicken coop door. The DPDT relay they're using is different to my relay so I'm finding it difficult to understand which wires connect to where. I'm ...
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When is a non-polarized electrolytic capacitor inappropriate?

I am recapping a vintage power supply and I've done similar before but I'm a hobbyist non-expert. My understanding has always been that using a non-polarized cap is acceptable where an polarized ...
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33 views

DPDT switch to control DPDT relay

this is a bit of a long shot but here goes. I need to buy a speed controller for an electric ride on car and I've had no success in finding one with a reverse polarity switch and one that also ...
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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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1answer
174 views

Proper Flyback Current Protection Circuit for Variable Voltage Solenoid Driver

I am using a darlington buffered op-amp to drive a solenoid motor at variable voltages (for variable speeds of actuation). Here is my circuit as it is now: I am wondering which of the two flyback ...
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What's the difference between polarization ratio ρ_C and ρ_L?

I have the following 2 equations in my textbook: ρ_L = E_Φ/E_θ ρ_C = E_R/E_L = (1 + jρ_L)/(1 - jρ_L) Both ρ_L and ρ_C are called polarization ratio. However, what's the difference between the two?...
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Puzzle: diode polarity in a vintage tachometer circuit

Once again, I'm trying to reverse engineer an old tachometer circuit--1970s vintage this time. There are three diodes on the circuit board, and two have absolutely no markings whatsoever. Can anyone ...
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347 views

Which one is the positive side?

I'm newbie, thus my simple question. In the schematic below, which side of the capacitors is the positive? Why? Or are they assuming that I have to use ceramic capacitors? Usually my schematics come ...
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Replace ONE 25v 47uf capacitor with FIVE 60v 10uf capacitors parallel?

MY 1000 Watt True Sine Power Inverter blew a 25V 47uf capacitor. The shell was rattling around inside, and the ribbons were exposed. Yay, I found the problem! Sooooo, how can I tell the mounting ...
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41 views

front and back LCD polarization film angles

I've taken apart an old dot matrix LCD because the polarized films are burnt. I removed the old ones and ordered a 10x10cm sheet (https://www.aliexpress.com/item/32804985320.html). I read that ...
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Maglev Train Propulsion System [closed]

So I'm trying to make a small Maglev train for a science fair project. I understand how to make the train levitate, but not how to make it move forward. When I look online, everyone explains how you ...
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Electrolytic capacitor polarity voltages

What happens if we feed an electrolytic capacitor only positive voltages while keeping the negative pin voltage lower than positive. for example positive pin 20V and negative pin 5V. Does it affect ...
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488 views

Switching between battery and external power sources with reverse polarity protection

In my design, I will use AA batteries to power the electronics board. As a requirement, also it should accept the power from external power supply (12V) - The board should automatically switch from ...
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737 views

What's the polarity of this capacitor?

Please, help me to determine the polarity of a RWA1C101MEG capacitor. I see a fat stripe on one side of the capacitor: Is this a positive or negative terminal?
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Cable wires - confirmation of live and ground

I bought a generic DC power extension cable and I'm trying to wire it to a connector with a cable attached. The connectors cable clearly has two wires - a red and black/+ and -. This is what I'm used ...
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29 views

Programmable polarity switch for DC circuit

My question concerns a future research project in electrocoagulation (water treatment) I am planning right now. I will have a lab power supply connected to two (or more) plates in water. The ...
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Parabolic wave equation, electric and magnetic field definitions

The split step solution for Parabolic Wave Equation (PWE) applied to the tropospheric propagation problem is: $$u(x+\Delta x, z)=e^{ikM(z)10^{-6}\Delta x}\mathfrak{F}^{-1}[e^{\frac{-ip^2\Delta x}{2k}}...
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507 views

Rapid Reverse polarity

This is the circuit for reverse voltage protection, R2 is the load of a motor. The problem is that there is a test where the changing of polarity is very fast ( <5ms) and the MOS burns. Power ...
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4answers
95 views

Reverse Polarity Protection, External Circuit

I'm trying to figure the best way to protect the external circuit from a short if a user mistakenly connects the sensor in the wrong polarity. I use a green object in the diagram to represent the ...
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1answer
289 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 ...
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Socket polarity

So recently I was installing these old fairy lights and its plug was burnt due to faulty connections, So I bought a new plug and replaced the old plug. I was wondering why do these fairy lights do not ...
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163 views

Reversed polarity of CR2025

My bike light uses two CR2032 batteries, which I replaced with CR2025 and some padding. It stopped giving light, so I removed the batteries and measured voltage. One battery gave 2.8 V, and another -1 ...
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1answer
41 views

ensuring transducer (transmitter) and receiver polarity

I am trying to implement a simple phased array of 7 transmitters rated 40 kHz. I have a few receivers to measure the acoustic field generated to validate if it works. What is a simple way to measure ...
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2answers
235 views

Can I trust in visual inspection to identify LED terminals?

In the figure above, LED A is a regular 5mm LED and the visual identification of its terminals polarity is well known. As you can see, on LED B the anode is identified by the longer leg, but the ...
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1answer
70 views

ESD Protection diode polarity

I'm using the following ESD protection diode: On the datasheet it says: MOUNTING POSITION: Any Does it mean I can assemble it at any polarity? (switch cathode and anode connections)
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21k views

limit switches to control motor direction

I am trying to use two limit switches and two DPDT relays to control the direction of the motor. When the power is applied the motor should rotate one direction (direction for this question isn't ...
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3answers
192 views

Phase or polarity for North America residential 240V

I understand that for North American residential, the three wires coming into the panel box are +120V,-120V, and Neutral. Is there such a thing as phase or polarity between these three wires? How is ...
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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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1answer
58 views

How can line code polarity inversion happen?

One of the disadvantages of some line codes like NRZ-L or RZ is that if a sudden change in polarity occurs, then all received bits will be erroneous (flipped). How can such a sudden change in ...
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1answer
118 views

AC/DC Power adapter plug: difference between center positive/negative

Why are some power adapters center positive and others center negative (less common, at least around me)? Is there any compelling reason, something that asks for one or the other for different ...
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2answers
492 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 ...
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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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246 views

Connect IR Emitter (+) to IR Receiver (+)?

I have a vehicle stereo deck that has an IR receiver input (+) and a steering wheel control module that has an IR emitter LED (+/-). The steering wheel control module, "translates" (using a mapping ...
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50 views

How to rapidly switch polarity of two plates?

If I have two metal plates, with P1 connected to V+, and P2 connected to GND, how can I alternate the polarity of these two plates? I wish to have P1 connected to GND, and P2 connected to V+. Then ...
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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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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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225 views

Why is the electrolytic capacitor not polarity sensitive?

The issue I was making a project in which I had to use a 2.2uF electrolytic capacitor in series with a microphone and weirdly, the circuit works even if I toggle the polarity of the capacitor, that ...

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