Questions tagged [polarity]

For questions about polarity considerations in electronics due to circuit components with polarity (e.g., diodes, transistors, polarized capacitors, batteries, etc.), polarity of quantities directional quantities (such as currents, voltages, electromagnetic fields, etc.), polarity symbols, etc.

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3 answers
551 views

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 ...
8 votes
9 answers
15k 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/...
0 votes
1 answer
71 views

Polarity negative or positive on DC barrel jack?

I have a DC port, can I make it positive or negative inside?
1 vote
2 answers
2k views

Peltier damage and efficiency when continuously reversing polarity

I am thinking about using peltier for both heating and cooling to maintain desired temperature profile in small area (2ft square at max) Can continuously changing polarity damage peltier module and ...
13 votes
4 answers
19k 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 from ...
1 vote
2 answers
824 views

Ceramic capacitors soldering "placement/vertical" polarity

I was wondering, since multilayer ceramic caps have layers like this: Image source Aren't they supposed to (for better performance) be soldered on the PCB as the above picture shows aka parallel to ...
0 votes
0 answers
25 views

Polarity Detection on Array Charging System for Autonomous Robot

Array Charging Concept I recently became interested in designing a charging system for an autonomous robot. The key requirement is that precise orientation of the robot is not necessary during ...
0 votes
2 answers
87 views

Do non-polarized capacitors need to be in any type of orientation?

I have submitted my PCB design to JLCPCB for population. They are asking me if the orientation of my capacitors are correct: My PCB and schematic of it: In the datasheet it states that these are non-...
4 votes
3 answers
440 views

Flyback Transformer Winding Direction

Looking at the basic Flyback Converter Topology, the coupled inductor polarity should be opposite in order for the circuit to operate properly. However, I am confused on how to implement the correct ...
10 votes
5 answers
6k views

Why is this 3-way speaker wired this way?

I found a service manual of a pair of 3-way speakers that were part of a mini integrated stereo system. These are Sony SS-H77 speakers, which have served me very well back in the day. Looking at the ...
2 votes
2 answers
550 views

Ethernet devices polarity reversal support

Does all Ethernet PHY devices support polarity reversal even if its not mentioned in the datasheet? [I mean polarity reversal by swapping TX+ with TX- (Like connecting TX+ to RX- or TX- to RX+). Is ...
5 votes
3 answers
9k views

Reverse polarity protection idea

I'm thinking about making a reverse polarity protection for a project. This is for a small line follower robot and I'm still deciding if I need a reverse polarity protection at all. It will be powered ...
3 votes
4 answers
506 views

Reversing the polarity on a relay

I have a single coil latching relay (HFD2/012-S-L2): + & - to set and - & + to reset. I have a 12 V supply to trigger the relay (via a push-button switch). My question is this - how to get the ...
3 votes
2 answers
479 views

Which side is the capacitor negative on this board? (IO/10 marking)

I removed a capacitor (C1 (400v/15uf) - highlighted in the picture) from this board to test on another board and now I want to put it back but I can't figure out the polarity. The traditional symbol ...
0 votes
2 answers
285 views

Why aren't I getting a voltage reading from my AC/DC power adapter

I am new to electrical engineering. I cut the barrel jack off the end of a 24V DC power adapter, exposing a red and white wire. I'm trying to determine the polarity of the red and white wires with a ...
2 votes
3 answers
2k views

What do you call a device that reverses polarity?

I am replacing a DC power supply used in a lab experiment. We need to be able to choose a positive or negative current. Bipolar power supplies in our power range (around 1 kW) are expensive, so I am ...
3 votes
3 answers
18k 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 ...
4 votes
2 answers
991 views

Footprint for Electrolytic Capacitor

I plan on using this capacitor on my project: https://datasheet.lcsc.com/lcsc/2209011730_KNSCHA-RVT330UF50V167RV085_C5155333.pdf This is an electrolytic capacitor (this means it has polarity.). The ...
34 votes
6 answers
143k 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 ...
1 vote
1 answer
110 views

High voltage polarity inverter circuit

I'm building a cloud chamber which needs to use an high voltage source. I'm using an electric fly swatter circuit which can generate about 4kV. The fact is that I want to use a button to switch the ...
2 votes
1 answer
267 views

Does USB3.0 support reverse polarity in SSTX and SSRX?

Is it possible to Sawp the +/- pins of SSRX and SSTX to make the routing easier and avoid using vias? Does USB3.0 support this reverse polarity?
0 votes
2 answers
190 views

Lighting Christmas Village Streetlights with LEDs

I purchased a Christmas village from Walmart on sale after the holiday season (Holiday time 30 piece Mini House Set). The 5 houses take 2x AAA batteries each, but I converted them to DC plugins ...
1 vote
1 answer
170 views

Testing transformer polarity with a signal generator and an oscilloscope

When using the above test setup to measure transformer polarity, the output on my oscilloscope shows a flat line at 0V, it does not register the waveform from the signal generator. The output on ...
1 vote
2 answers
1k 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 ...
3 votes
2 answers
993 views

I do not understand this polarity symbol with 3 circles: positive, round, negative, and no lines

I am trying to figure out what is the right polarity of a power adapter for a small practice amplifier. I know it is 9 VDC and I figured out the size of the plug and I know the wattage needed. I do ...
0 votes
1 answer
72 views

AC polarity detection circuitry

The three wires in a marinr 120 VAC shore-power circuit are normally black for power, white for neutral, and green for ground. I’m searching for a circuit that will power an idiot-light in order to ...
0 votes
1 answer
70 views

What is the polarity of a custom power supply? [closed]

I have a custom power adapter (this one), but I do not understand what the correct polarity is, as its tip can be reversed. In the picture I have highlighted the marks in the current situation (so the ...
0 votes
3 answers
1k views

Which of these wires is positive and which is negative?

I know that in DC circuits the colour code is often (but not always) that red is positive and black is negative. On this AC mains wiring the wires are blue and brown. Does anyone know which is which? ...
1 vote
3 answers
167 views

DC christmas string lights without polarity

My sister was doing an electronics project assigned from school and she was given sets of christmas light-looking bulbs in sockets with two wires sticking out of each. When she asked me for help ( it ...
1 vote
2 answers
229 views

Can you change the polarity of a flyback transformer by swapping the output pins?

I am using the following flyback transformer from Pulse electronics: I am typically used to seeing the dots reversed on the diagram. For this transformer, would current be flowing out of pins 5, 9 ...
7 votes
6 answers
1k views

Inductor polarity

Let's say an inductor has DC current going through long enough for it to completely build it's electro magnetic field. If the source voltage then goes lower, the inductor will 'use' the energy stored ...
0 votes
1 answer
264 views

Should a start-stop interrupt positive or negative? (Why?)

This answer shows a "standard" start-stop circuit. I was trying to design my own, and came up with a design that is essentially the same, except that it interrupts negative, with positive ...
3 votes
1 answer
3k views

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 ...
1 vote
2 answers
83 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. ...
1 vote
3 answers
3k views

Simple H-bridge polarity reversal

I am trying to reverse the polarity on a rather beefy motor (5 amp, 60 V) in the most simple way possible. I need to build an H-bridge just to reverse the current, I am controlling speed elsewhere. ...
0 votes
3 answers
627 views

How to figure out the direction of current and polarity of a circuit element?

How do I determine the direction of current in the boxed region? Also, how do I figure out the polarity of the resistor?
0 votes
2 answers
170 views

How can I determine polarity requirements for a device that is missing its power supply?

I have a MASSFIDELITY relay, wireless Bluetooth receiver for which the power supply is missing. I found a manual for the device that states it requires DC 5V 1A power, but says nothing about polarity. ...
-2 votes
2 answers
4k views

Which wire is positive on this audio jack (blue and white)?

Which wire is positive and which is negative on an audio jack wire that I have cut off to do some experimental work? I have searched the internet and a lot of answers contradict each other.
0 votes
1 answer
173 views

Understanding which P FET to use for reverse polarity protection

I use a Schottky diode as reverse polarity protection on earlier versions but have decided to change to something more appropriate and energy efficient. The voltage input on the left is a 12-14.8 V ...
2 votes
3 answers
78 views

Can polarity protection circuit be useful for also data transmission?

For example, CANBUS has two transmission lines CAN_HIGH and CAN_LOW. Polarity matters. Would the performance be affected if a polarity protection circuit with couple of diodes would be implemented? ...
-1 votes
2 answers
164 views

Does time constant or rise time concept apply in transformers as well? [closed]

I am new to electrical engineering. I have made a transformer where I kept one primary and two secondaries, there's an air gap between the primary leg and secondaries on toroidal core, you can watch ...
4 votes
3 answers
453 views

Polarity of TVS diode is unclear

I have a question regarding the DESD1LIN2WSQ TVS diode by Diodes Inc. which I want to use to protect some 24V IOs of a microcontroller board. Until now, the TVS diodes I worked with always had the ...
1 vote
2 answers
203 views

Is this the correct way to drive a double coil latching relay?

I have found a double coil latching relay which has the following diagram in the datasheet (http://www.fanhar.com/en/uploads/files/FH44L.pdf) : I am quite confused by the instruction "The common ...
0 votes
0 answers
81 views

Determining Polarity Of Unmarked AC Adapter With Voltmeter

I need to replace an adapter that no longer works (for a fibre optic Christmas tree). I do not see any indications for polarity on the adapter (or anywhere else) and I do not have the manual. I read ...
0 votes
1 answer
152 views

Inductor polarity

By looking on the picture of the inductor PE-0402CL470JTT and the datasheet, we can notice a black pole and a white pole for the inductor. Is there any difference between poles? The datasheet doesn't ...
3 votes
1 answer
3k 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 ...
0 votes
2 answers
98 views

Inductor voltage polarity

I am trying to understand the current direction during non-steady states of inductor. The circuit I am testing is very simple : ...
2 votes
4 answers
1k views

Difference between phase and polarity?

Long story short, I did a bit of a career change, I'm now doing electrical engineering with an architecture firm instead of embedded systems. So I've jumped from the simple world of DC to the land of ...
0 votes
3 answers
319 views

Unusual Polarity Symbols on Universal Adaptor [closed]

The polarity symbols on my universal adapter look a bit different to ones I have seen. Which setting should I use to power the device shown please, top or bottom position for the switch on the adapter?...
4 votes
2 answers
381 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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