Questions tagged [reverse-polarity]
For questions about the operation and/or protection of polarized electronic components when biased in reverse. Consider also using the "protection" tag and/or tag(s) for the polarized components in question (e.g. "diodes").
322
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MIL-STD-1275E surge protection
I am building a protection circuit for MIL-STD-1275E,
and my manager says the circuit will not work and to figure it out.
now I have addressed all the 4 main events in said STD: the surge, the spikes, ...
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Common mode choke placement in DC input circuit
I have a PCB that is currently not passing EMC tests. The most problematic issue is common mode noise on the power line, thus a common mode choke was proposed. My circuit already includes over-voltage ...
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2
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59
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Reverse polarity protection on a 5 V LED strip supply
I'm looking to use an AOD413A (P Channel MOSFET) as reverse polarity protection on my LED strip controller which uses 7.7 A at 5 V DC. I think I partially understand how to choose the right one, but I'...
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ORing of 2 batteries and reverse polarity protection
I am trying to find a solution for ORing of 2 Lithium batteries, that also provides reverse polarity protection. Single cells are used, so the voltage will range from about 3V to 4.2V. Also, the two ...
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92
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Reverse Polarity Circuit Protection
I have an adjustable voltage battery charger that goes from 6v to 14.8v and I need a reverse polarity protection to substitute the old one, which doesn't work. I mounted a circuit based on the ...
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58
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Easy Overvoltage and Reverse polarity protection circuit
I'm looking for the simplest and most effective way to add an overvoltage and reverse polarity protection network to a signal line connected to an MCU, the maximum allowable voltage at the MCU pin is ...
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66
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Finding Is, Id of a Diode in reverse-bias mode
Excuse me, sir,
I'm currently finishing my lab experiment report but I got stuck finding Id and Is of a Diode in reverse-biased mode.
Here is the question: Vin is in the range of 0V to 18V with the ...
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68
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Reverse current blocking FET circuit for batteries, does it work?
Based off of a previous post found here, I've created this circuit below to simulate the reverse current coming back from an FET. I've replaced the switch with a NMOS that's controlled by the presence ...
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Clarification on the Application of a p-Channel MOSFET in a Circuit Diagram
I am seeking clarification on the application of a p-channel MOSFET as illustrated in the diagram below. Could someone please provide an explanation?
In the diagram, legs 1, 2, 6, and 5 serve as ...
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4
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241
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Polarity change circuit - reverse polarity with only one relay
I was looking for a polarity change circuit - (reverse polarity) with a single relay but I didn't find it or maybe I don't identify it, the only thing I've found are with two relays, do you have any ...
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Auto sun tracking relay wiring?
Ok here's a bullet list of what I'm working with
• 1 5v DC 2 wire reversible electric motor
• External 5v DC power source (battery pack)
• 2 12v small solar panels ( for signaling left or right ...
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2
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Does a negative base current in BJT npn mean that the operation mode is Reverse Active?
Given Vce = 2V, Ic = 1.7mA, and Ie = 1.6 mA, I used KCL to determine that Ib = -0.1 mA. Does this mean that the BJT npn is in reverse active mode?
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Appropriate Overcurrent, Overvoltage, and Reverse Polarity Protection Circuit for Raspberry Pi 4?
I'm new to electronics but I'm trying to power a Raspberry Pi 4 (model b) using an external power supply for testing purposes[5V @ 3A]. This is possible via the GPIO, using pin 2 and pin 6 as ground ...
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2
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109
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How to protect a device from reverse polarity and over-voltage?
I am designing a device that will include a DC power jack. There is an external wall adapter that converts the 110-230 VAC from the mains to 20 VDC. Here is the schematic:
I intend to use a standard ...
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4
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1k
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How to choose reverse polarity protection - diode vs MOSFET
I am reviewing the power stage of a board which is to be connected to a wide range of cars and motorbikes, with internal combustion engines, old, new, 2 stroke, 4 stroke, etc.
Current schematic looks ...
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Reverse polarity, over-voltage and over-current protection for a "breadboard add-on board"
I am designing a small utility board that should attach to a breadboard and take power from it.
It can be described as the opposite of this SparkFun Breadboard Power Supply: instead of powering the ...
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2
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634
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BJT B-E Zenering: whither the collector?
So, I'm trying to analyze how the circuit in this question behaves when subject to reverse battery (vs. being driven from OUT to IN), and I'm running into a severe snag in the process, though. It ...
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167
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Reverse polarity protection for parallel connection of 18650 batteries
I want to use two Li-Ion 18650 batteries in the device. The batteries need to be connected in parallel and they can be removed from the device (holder).
The device itself is protected from incorrect ...
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3
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1
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235
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Same MOSFET component but reversed arrow
I'm trying to implement a USB PD controller, STUSB4500, but the typical application example shows 2x P-Channel MOSFETs STL6P3LLH6 with different arrow indications. I'm now confused about the pins, T4 ...
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57
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High negative voltage cut-off for op-amp from dual-rail power supply
In the picture I have a circuit that prevents reverse polarity and cuts the voltage with respect to the Zener diode (15 V) as a voltage reference for positive voltage output.
How do I apply the same ...
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130
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How to design short circuit and reverse polarity protection for PCB?
I have read many posts and articles about short circuit and reverse polarity protection design for a PCB, but still I am quite confused about the industry standard/common principles here. The ...
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88
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Reverse polarity with feedback
The below is a reverse polarity circuit with additional components around it. I would like to understand the exact functionality of the additional circuitry in dotted lines.
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260
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TVS2201 clamping diode failed at 27 V
In the development of ESD protection and reverse polarity, I encountered a problem. The circuit is supposed to prevent reverse polarity (it does, we tested it).
During testing, I applied a voltage of ...
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208
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Trying to reverse a Crompton Parkinson motor
Completely out of my depth here ~ trying to repurpose an old sewing machine motor to turn a flour mill. Prezzie for the wife who is baking sourdough.
But I need to reverse the direction.
Tried ...
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2
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272
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How do the protection diodes actually protect the supplies in this case?
Regarding making a dual supply from two single supplies, I see two Schottky diodes are placed between the supply terminals in reverse biased way as in the following example I drew. The diodes are ...
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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 ...
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98
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Reverse polarity protection + inrush current limiting with mosfets schematic
What do you think about this schematic? I want to put this before a DCDC 24 to 5V with maximum 1A. Any comments or suggestions? The aim of this circuit is to have a soft start with the resistor R2 in ...
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3
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258
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Connect a single LED to a reversable circuit?
I have a need to install a single small LED that will illuminate whenever a circuit is active. The circuit controls a small motor, and reverses polarity depending on which way the motor is operating. ...
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121
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Reverse polarity protection with bidirectional current flow
I'm working on a reverse polarity protection circuit in order to avoid possible damage if the source (a 18650 3.7V battery) is mounted in the opposite direction.
The circuit is straightforward; my ...
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332
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Reverse polarity protection and inrush current limiting - back to back mosfets
I was testing this circuit in LTspice, it would protect my boards from reverse polarity and limit the inrush current to the input capacitor of a DC-DC (buck or LDO),
but the simulation gave me this ...
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261
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Polarity on Current Transformer
In this part,
What is the correct way of orientation? In which pin should I give the input signal? Should the current flow from P1 to P2?
Please let me know the correct orientation and how to find it....
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94
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How to choose a MOSFET based on maximum forward voltage
I have a 5V DC input to a fixed 5V to 3.3V LDO (LM3940) that I want to add reverse polarity protection in front of via a P-channel MOSFET.
What I am struggling to determine is how to analyze/choose a ...
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192
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Which specific type of P-MOSFET is suitable for Reverse Polarity protection for 18650 li-ion battery circuit?
I'd like to make a reverse polarity protection circuit for 18650 3,7V Li-ion battery (like here: Can I use a p channel mosfet as reverse polarity protection but still charge a Li-Ion battery?)
I only ...
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Alternatives to reversing polarity on a DC to DC step up converter?
I am looking to drive a 12V DC motor with an encoder attached (Motor Link). The battery I am using is 6V (Battery Link) which requires me to use a DC-to-DC step-up converter (Converter Link). To ...
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Trying to make a 12V Timer Relay With Reversing Voltage, Problems when voltage reversed
So my idea seemed simple, try to hodgepodge together with parts on hand, a device that when one trigger is pressed, timer relay turns on for 5 seconds, it applies 12v to a set of leads, opening a ...
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Reverse voltage protection for four 18650 cells
I would like to protect my robot from reverse voltage which is powered by four 18650 cells. Is option 1 sufficient or do I need at least three diodes? I know that using diodes comes with a voltage ...
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88
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Will my circuit get damaged fom a reverse polarity event?
I have a FE1.1S USB Hub IC, the fe1.1S IC typically has its own 3v3 regulator but in this case an AP2213 LDO is powering the USB HUB. I would like to know if the USB hub is safe during a reverse input ...
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Need help in understanding circuit of PMOS reverse
Given 2 PMOS enhancement: Vdd = 5 V, k1/k2 = 9, Vt = -1.
I'm trying to find Voh, Vol, Vil, Vih.
I would appreciate help and explanation.
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How to calculate the gate voltage and Vgs in this N-channel MOSFET reverse-polarity protection circuit?
The schematic below uses an N-channel instead of a P-channel to block reverse-polarity voltage from occurring. This means the gate voltage (and Vgs) must be positive. But there are two options I've ...
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2
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Will this NMOS MOSFET reverse-polarity protection circuit work?
Based on the helpful advice from the community, I realised the first schematic I made would not work as a protection for reverse polarity well due to a couple of flaws including the diode having to be ...
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2
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500
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N Channel MOSFET reverse voltage protection proposal
While learning how to make a buck converter, I realised that using P channel mosfets for reverse voltage protection is one of the best ways, but I think it could be better using an N channel using the ...
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How to limit P-channel MOSFET gate voltage?
While working on my first buck converter I thought it would be a good idea to add reverse-polarity protection. So I went and searched for what would be the best (and easiest) way to do it and found P-...
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Reverse voltage protection of boost converter with Schottky diode shows small voltage output
I am testing reverse voltage protection using Schottky diode and found small but not trivial level of voltage leakage when combined with boost module in open circuit.
Here, as you can see, the 12 V is ...
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Is it an issue that type F outlets are not polarized?
A lot of European countries use type F outlets that are not polarized, i.e. you can plug in both orientations.
This means that there is a big risk (50%) to invert live and neutral.
Is that not a major ...
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267
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Where is my mistake with this reverse-polarity protection circuit?
I am trying to do reverse-polarity protection on a 24V PCB. I read up on the PMOSFET method and I thought I had understood it, implemented it as follows:
If I connect the power supply correctly, the ...
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312
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How to reverse the polarity of a DC brushless hobby motor?
How can I reverse a motor safely that draws about 70 A on 4 s (14.8 V), and additionally how do ESCs (Electronic Speed Controller) that have this capability built into them do it?
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483
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LED reverse voltage rating
I am looking at an LED and trying to understand the Reverse Voltage parameter because it doesn't make sense to anything I test on the bench. Pretty much every LED you find will specify a Reverse ...
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261
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Struggling with a 12 V reversing motor
I’m struggling with wiring a reversing DC tailgate window motor in my jeep. It’s a circuit with two relays and two switches. I was able to wire the first switch without issues but wiring a second ...
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Why is there a polarized capacitor symbol in an AC circuit?
I am confused. My question is very basic, someone please enlighten me.
If polarized capacitors should not be used in reverse polarity then why does every textbook (like the one I am using, Grob's ...
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Is this a functional and reliable Reverse polarity protection?
Guys, I am trying here to design a UPS controlling board, I designed this circuit and it was to some extent functional and it draws approximately 16mA - 20mA (I don't want to use the traditional one ...
