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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 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 ...
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2answers
720 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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1answer
295 views

Does biphasic wave mean current is bidirectional?

Does biphasic wave mean current is going bidirectional in a circuit?
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1answer
232 views

+ve & -ve vs 5v and GND

I am learning hardware form a software background (playing with Arduino) and I am having difficulty remembering absolute wiring basics. Bu board has a 5v and gnd pin, whilst my component has + & -...
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1answer
355 views

Fundamental questions about BJT transistors

Take a standard NPN transistor. The doping of each element of the transistor is in the name. This is what is inside the transistor... Source of image: Bipolarer - Transistor, gif The left "slice" of ...
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1answer
593 views

DC Motor circuit polarised 2 directions switches

I'm totally new to electronicS and do not understand a lot and I've read other posts but people seem to be asking different things to me so apologies in advance if this has been covered but I've typed ...
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3answers
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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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1answer
652 views

Capacitor polarity and overvoltage

after watching few videos on YouTube with exploding capacitors i decided to learn few things about the polarity and the voltage rates by trying to make a capacitor explode. I made few test to try on ...
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1answer
56 views

EM wave polarization check

I am trying to recall the quick way to check the EM polarization theoretically, I mean if I have a wave described as (ssume capital letters are vectorial fields) \begin{equation} \ E = E_o *exp(j* \...
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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 ...
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1answer
1k views

How to figure out polarity of a polarized capacitor in a circuit

I've found myself a number of time trying to build a circuit from a schematics that does not provide any polarity indication for caps (probably because the designer used non-polarized caps in the ...
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2answers
749 views

Trying to understand flyback diodes and general diode orientation

Let's start with this: I know the top image is of a flyback diode. I also get that its purpose is to protect the power supply from a voltage spike when the electromagnet releases. So I've gotten that ...
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1answer
971 views

74HC595 Shift register - output pin polarity

Most shift register tutorials I've seen have the output pins connected to ground (for instance: http://www.arduino.cc/en/Tutorial/ShiftOut), however I've seen at least one circuit that connects them ...
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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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3answers
5k views

Reversing polarity of motor with timer

I have a timer that allows me to preset times and run a motor for a predetermined amount of seconds. I need this to reverse polarity as soon as this predetermined time has expired. The timer is a ...
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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
7k views

Do electret microphones have polarity?

So do electret mics have polarity? The following circuits seem to contradict each other... 1) 2) Now the problem is one image shows polarity while the other one does not!! What's the holdup here?
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1answer
953 views

Capacitive transformerless power supply, AC polarity problem

I have implemented a "Capacitive transformerless power supply" to control a microcontroller-based circuit that contains capacitive touch sensors, and I had an "AC polarity problem" Surprisingly, the ...
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3answers
14k views

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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1answer
622 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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1answer
6k views

Coil Winding Sense of Inductor/Transformers and Output Polarity

Given a solenoidal coil, if it is wound in one sense (say clockwise), would the output from it, in terms of polarity, be equivalent to another coil, wound in the opposite sense (counter-clockwise), ...
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3answers
752 views

How to remove energy from inductor using semiconductors?

So I have this coil and I'm driving dc current through it. This coil has inductance and thus stores energy from the dc current. I have to remove this energy before I can change the polarity of my h-...
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1answer
2k views

How to build an H-bridge using MOSFETs? [duplicate]

I want to reverse the polarity of my current source, which is a capacitor in this case, in the middle of discharging phase. Also the capacitor bank is being discharged through a coil to make a short ...
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2answers
2k views

Inverting (Buck-boost) converter polarity problem

I have trouble understanding something in the circuit below. It is inverting converter, seems quite easy, but the part I don't get is when the switch is OFF we have forward-biased diode, i.e. plus on ...
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2answers
19k 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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2answers
1k views

On/Off DC power indicator [duplicate]

I am pretty sure that this should be simple but the answer is eluding me. Basically I would like a simple 12V DC circuit that lights one LED (red) when a power switch to a pump is off and would ...
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3answers
16k views

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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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
11k views

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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1answer
199 views

Isolating polarities on a series wired battery bank

Can anyone, with 100% certainty (that means you know what you are talking about) tell me how to "isolate" the positive from the negative posts electrically in one direction so I have a true 'positive' ...
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0answers
1k views

Ubiquiti/UniFi PCB component identification and polarity question

I stupidly dropped a brand new Ubiquiti UniFi AP-LR wireless access point on the floor. The impact broke off a component (shown in the picture) from the PCB which is preventing the AP from working ...
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1answer
5k views

Can I damage a device using opposite polarity? [closed]

I have a device that requires input of 12V DC with positive polarity and a power supply that outputs 12V DC negative polarity (see figures below). Can I plug it in to try to see if it's working or ...
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3answers
5k views

Does the input polarity matter for a 12V DC adapter?

I bought a car cigarette DC adapter yesterday with the following specs: Input: DC 12V Output: DC 17V I'm planning to connect it to a 12V battery I have at home,...
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1answer
1k views

Does the polarity of my AC adapter match that of the device? [closed]

Looking at the symbols, I think the polarity matches the adapter and device (tip positive), however the design of the symbol is different which is is confusing me, so I want to be 100% certain that ...
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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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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
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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1answer
675 views

DMM Auto-Polarity / Polarity detection

I have understood how auto-ranging is typically achieved on a digital multimeter, but I'm having trouble finding an example of how (DC) polarity is handled. How does the meter know if a voltage is ...
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1answer
46k views

How to check DC polarity using a multimeter

How can we check DC polarity using multimeter? If the DC cable (the positive and negative end) is connected in the cable rack (terminal block) how can one identify which cable is positive and which ...
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1answer
1k views

Reverse polarity protection with MOSFET: low voltage drop, 1-50V supply

I have a circuit that tests DC PSUs. They are typically unregulated and unsmoothed, up to 50V. It performs tests to establish I/V curves, down to about 1V, and up to about 3A. I want a sub-circuit ...
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1answer
220 views

Detecting polarity in a DC device [closed]

I have a device which can be charged with 5v DC. I wish to locate an adaptor for it, but not knowing the device's polarity, I'm stuck. Please note: The device requires 5v DC but has no polarity ...
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1answer
12k views

Determine polarity of crystal oscillator [closed]

A two-pinned 13.824 MHz crystal oscillator broke away from the pads on a PCB board. One pad is labeled + and the other is GND. Do two-pin crystal oscillators have specific polarity?
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0answers
413 views

Op-amp: Floating input (Multisim)

I found this circuit from Encyclopedia of Electronic Circuits Volumes 1 by RUDOLF F. GRAF I used Multisim to simulate. When switches S1 and S2 are open (U1A@3 and U1B@6 are floating) and I measured ...
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1answer
233 views

Is there a convention for the polarity of voltage specified as \$V_{XY}\$? [duplicate]

Inspired by this answer, which includes the image: Which solicited the comment: No, you have the polarity of Vce shown backwards in the diagram [...] The diagram seems consistent to me: the ...
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1answer
2k views

Changing the polarity of electromagnet using H-Bridge

I have made an electromagnet using copper coil of 1.0 mm diameter, iron core of 2 cm dia & 8 cm length for my project. Supplied voltage is 12 VDC and current it consumes is 9.0 Amp. It has 1.5 Ohm ...
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2answers
2k views

Using a pulse-width modulated signal to possibly reverse polarity

I'm trying to help an artist control a simple DC motor using a single signal. The signal is a digital output, 0/5V, and the motor runs with max 36V. The motor needs to run forwards and backwards. ...
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3answers
6k views

Motor polarity reversing circuit using just SPDT switches

I have a 6v DC motor that controls a physical system similar to a window blind, using one SPDT toggle switch and two SPDT microswitches for control. I have seen similar setups with hoists, however I ...
2
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1answer
307 views

Will an electrolytic capacitor work reliably with 0 VDC and 100 mVAC?

I ran across an instrumentation amplifier datasheet from "THAT Corporation", and noticed the polarized capacitor in series with the gain resistor: It is a typical 3 op-amp in-amp, so the differential ...
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1answer
2k views

How do the hybrid-pi models between N-channel and P-channel JFETs differ?

This is the hybrid-pi model of an n-channel JFET. An answer on here claimed that the only difference between p-channel and n-channel JFETs is that voltages are reversed. How would this apply to the ...
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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 ...