Questions tagged [reverse-polarity]

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2
votes
1answer
70 views

Overvoltage and reverse polarity protection

There are two well-known circuits well described in the Internet, including this site: Reverse polarity protection with P-channel MOSFET; Overvoltage protection with SCR and Zener (so-called "...
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2answers
73 views

Can one of the capacitors in series get negative Voltage when discharging?

Supppose i have the following circuit. And I complelty discharge all the capacitors by having a load on them for a long time, so there will be 0V overall. Let's assume the one in the middle has a ...
0
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4answers
69 views

Reverse polarity protection for battery powered application

Im designing battery powered application and need reverse polarity protection. My system specs: 4.5v(3x AA batteries) in and system running on 3.3v. Im using MCP1711T-33I/OT LDO to convert 4.5v to 3....
8
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1answer
221 views

Designing an effective power supply for embedded products

I'm currently designing several embedded microcontroller products to be powered from a wall outlet. I plan to use wall-wart power supplies to give an input of approximately 5-9V DC but I want the ...
3
votes
1answer
64 views

Rectifying reversible polarity battery with minimal power loss

I'd like to build a battery-powered DC power supply that will accept a single-cell battery in either polarity (i.e. it doesn't matter which way you put the battery in). I'm thinking of using the ...
0
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2answers
87 views

Mains AC Reverse Polarity - Has this damaged my fridge/freezer PCB? [closed]

In the UK, I had a smart meter installed a few weeks ago. My 4 year old Panasonic fridge/freezer (NR-B53VW2-WB) was working fine before the electric meter switch. After the install, after the engineer ...
0
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0answers
33 views

Reverse polarity diode, which diode is better: SB140 or 1N5819

I want to add reverse voltage polarity protection into my circuit to protect the components in my Arduino robot. But i want to know which diode has the edge on the other: SB140 or 1N5819? Or is there ...
4
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3answers
123 views

Designing reverse and overvoltage protection at 3.3V

I have a barrel jack powered design that I'm making, but I would like to prevent damage in the case of reverse polarity (sleeve is positive instead of negative) and overvoltage (plugging in a 12V ...
3
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4answers
519 views

How to avoid voltage drop when using full bridge rectifier as reverse polarity protection

I found a couple of old bridge rectifiers. After reading some docs and tutorials about reverse polarity protection decided to give them a try. The problem is nobody offered a solution against the ...
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0answers
33 views

Reverse voltage protection for TBD62083

Good day everybody. This is my first question on this site so bare with me :) . I am working on general purpose driver using TBD62083 (replacement of darlington array ULN2803). As you can see the ...
1
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0answers
26 views

Looking for circuit, reversing polarity of DC motor

Consider I have 2 inputs, A and B. I need help with a circuit that does the following if only A is active (A,B : 1,0), then the motor should run clockwise if only B is active (A,B : 0,1), then the ...
1
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2answers
73 views

Can I put a low current relay between line (or neutral) and the ground wires to detect polarity?

Can I put a low current (<5 mA) 230V coil, NC (normal close contact) relay between one wire of mains and the ground (earth) wire in order to check mains polarity? In theory if the wire is line (...
3
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2answers
493 views

Voltage monitor circuit (reverse polarity protection with high voltage cut-off)

I want to make a circuit which performs these tasks: 1) Protect the load against reverse polarity. 2) Protect the load against over voltage. Load = Raspberry pi Reason for this circuit - Pi is not ...
0
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1answer
49 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 ...
2
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1answer
93 views

Can an electrolytic capacitor be charged reversed bias by a small voltage? [duplicate]

In this monostable circuit the C1 capacitor is reverse biased. When T1 is closed and C1 is discharged what will happen on the right side of C1? Will it charge up to 0.6 volts so that T2 can be ...
0
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1answer
53 views

Trying to come up with a overvoltage overcurrent reverse polarity protection circuit, is option 3 done right?

I´m reading for the past week about P-Channel mosfet reverse polarity protection circuits. Then I´ve found this post http://kaktuscircuits.blogspot.com/2014/07/reverse-polarity-and-overvoltage.html ...
0
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2answers
69 views

P-Channel MOSFET reverse polarity protection on NMOS array chip

I'm trying to achieve reverse polarity protection for the TPL7404LADR chip which is basically an updated version of the ULN2003 darling transistor array. To do this I want to use a P Channel MOSFET ...
0
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0answers
20 views

Mixing Reverse Polarity Protection PMOS with a Piezo Element

I have a circuit that powers some leds when vibrations are detected. I am trying to integrate a PMOS for reverse polarity battery protection. When the PMOS is present the circuit simulation fails as ...
3
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1answer
53 views

MOSFET selection for high current application

I am designing a reverse polarity protection using the LM74610 chip.Now, my circuit can take peaks of about 90Amps and constant of 50-52Amps. This is quite a load and I want to select the right MOSFET....
0
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1answer
45 views

Using P-MOSFET with Gate and Source have same voltage to protect reverse current

I have a question when I am working on MP2639A 2-cell LIPO charger (+8V4) from USB +5V. The recommend schematic uses P-MOSFET to protect reverse current from Load back to a USB plug. taken from ...
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2answers
79 views

Diode behavior when reverse biased with small voltage

I'm designing a simple circuit to use a lithium-metal coin battery as a backup power supply, and I'm considering something simple like this: simulate this circuit – Schematic created using ...
0
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0answers
32 views

Simple Animatronic - slow repeating/reciprocal motion for a window display

I am trying to rig a contraption to pull a model hot air balloon back and forth along a curved horizontal track. Its motion is both horizontal (6’) and vertical. I have built the track and rigged the ...
2
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1answer
57 views

Circuit protection component arrangement

I was reading this thread and decided that in general it's better to place the reverse polarity protection diode D2 after the TVS rather than before it, and to instead use a bidirectional TVS for D1 (...
0
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1answer
120 views

How does this BJT affect the circuit? If it does, how should I simulate on Circuitlab to see the effect?

I am trying to understand how NPN Q23 in the picture below affects the operation of the left circuit. If it doesn't then what we get is the circuit on the right with the only transistor now being Q30....
2
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2answers
128 views

How to tell if a capacitor is still good?

I was replacing a 400 V 120 µF capacitor in a power supply (AC 120 V - 19 V DC 4.62 A). I tested the dc out end while it was still plugged in and got 0.07 V. As far as I can tell although being ...
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0answers
59 views

Reverse voltage on MIC5225 in particular and other LDO in general

This question has been asked many times before, for example about LD1117, MCP1703, LM78M05CT, MIC2920A, ADP7142 etc. Why am I asking it again? a) From reading all those topics it seems that the ...
0
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1answer
60 views

Can a reverse battery be considered a resistance?

In a simple circuit with 2 batteries and a simple load, one of them supplies 10V and the other 3V. The 3V one is reverse, in a way that the total output of batteries is 7V. Can this 3V battery be ...
0
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1answer
263 views

Reverse voltage protection circuit explanation

Considering this circuit : (The complete schematic can be found following this link - page 23) It is connected on the return path of an IC to provide reverse-voltage protection. I understand that ...
1
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3answers
452 views

A question about reverse polarity protection diode

Is the function of 1N4001 before the 5V regulator reverse polarity protection? Is this a fine method? And I sometimes see 1N4148. Can any diode(besides zener) be used for such function?
1
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3answers
225 views

Reversing P-channel mosfet for polarity protection component selection

Situation: I'm trying to implement a reverse polarity circuit using a p-channel mosfet and a voltage divider using a resistor + schottsky diode. More information here if you need a refresher. The key ...
0
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1answer
68 views

What will happen if P-channel Enhancement type MOSFET gate kept open while connected as diode in real case

[ I am using MOSFET as diode for polarity protection of system. Vehicle supply of 12V is applied to drain & system is connected to source. Gate kept open purpose. I have simulated attached ...
4
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2answers
619 views

High-side vs low-side reverse polarity protection

I need to make a reverse polarity and over-voltage protection for a fairly powerful device (45W @ 12V input) and after some research I noticed a weird peculiarity. A typical reverse polarity ...
1
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1answer
56 views

Reverse polarity protection for symmetrical input

I have a symmetrical voltage input I need to protect agains reverse polarity, and over-voltage. Here is the reverse polarity protection I designed. Is it correct ? I can't find much information about ...
0
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1answer
69 views

LED behavior during 24 VAC negative half cycle

I don't understand why the green portion of LED3 is able to conduct. Since the path marked in green represents the negative half-cycle of the 24VAC isn't the green LED reverse biased therefore no ...
0
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1answer
133 views

Reverse Polarity and TVS Diodes Not Working?

This is a follow up to this issue: Damaged TPL7407LA Transistor Array (*Updated With Scope Testing Images*) We are experiencing both reverse polarity and transient voltage spikes in our automotive ...
5
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1answer
701 views

Replacing two LEDs with a 2-pin, bicolor LED, using a circuit that reverses polarity based on two inputs

I'm working with a commercially available circuit that can optionally be configured to disable its internal LEDs and use two external LEDs. This post discusses the use of external LEDs. One LED or the ...
0
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1answer
340 views

Have I fried the transistor in this circuit?

It was a germanium PNP transistor. I might've pressed the button too. I saw transistors used as capacitors that were connected like this, but they weren't germaniums. What current (if any) has flown ...
1
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2answers
348 views

Protecting a power supply from inductive load

I recently got a PeakTech 6225A power supply for my hobby of making/"tinkering"/messing around. I get many parts that I want power separately to diagnose them. I also get a lot of electromotors and ...
0
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0answers
41 views

Low Side Reverse Protection Diode + Wide Battery Input Range

Quick background: I'm working on a very wide input range for a battery powered application (capability for two different types of chemistries). In the original design, a low side NFET was used as ...
0
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1answer
122 views

Is it possible for a voltage multiplier to be used to provide both positive and negative voltage?

What I was wondering is it is possible to use a single voltage multiplier to provide a negative and positive voltage. Referring to this voltage doubler circuit, if you connect a capacitor to the top ...
2
votes
3answers
374 views

How to find Voltage based on reference nodes?

I came across this problem and I'm trying to really understand it. VB is the voltage drop across a particular element, it is the change in voltage from node a to node b. Find the value of VB in ...
2
votes
2answers
370 views

How do I calculate the diode parameters for reverse polarity protection?

I understand that a diode allows current to flow in one direction only, and that inserting a diode in series with a power source will protect the circuit from a reverse polarity battery. How do I ...
0
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1answer
67 views

High Side Driver IC - Application Information

I have a question regarding VN5025AJ-E: High side driver IC. Datasheet link - https://www.st.com/resource/en/datasheet/vn5025aj-e.pdf In the figure you can see the application schematic. In the ...
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3answers
825 views

Reversing USB power polarity, but no black wire

My goal is to create a USB-to-USB cable with reversed polarity in order to charge an old Gameboy Advanced SP. I could just go on Amazon and buy a charging cable, but I do enjoy a fun little project ...
0
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1answer
296 views

What part of a mobile phone charger makes it safe to be charged with opposites polarity? [closed]

A mobile phone charger works regardless of whether the charger is the right side up or upside down. As I know, batteries should not be charged with wrong polarity. How do those chargers accomplish ...
0
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1answer
57 views

How to deal with extra pins on reversible connectors?

I want a header on my board to be reversible. The header has 4 UARTs, 4 power pins (VA,VB,VC,VD), and power (3V3) and PWM for a servo. The functions of most of the signal pins of the header are ...
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0answers
176 views

NMOS Gate RC Filter Values

I am designing a Reverse Polarity Protection circuit for a project by using an n-channel MOSFET. A basic schematic is shown here. I've added an RC filter so that the voltage on the Gate pin changes ...
1
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1answer
165 views

Protecting against reverse polarity

I'm building a JTAG programmer for the old Motorola 56k devices and I want to add some circuit protection before having some boards built. I'm more of a firmware/digital guy, but here's what I came up ...
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2answers
295 views

Protecting microcontroller digital output pin from ESD, reverse connection, and other possible user error

I want to protect an output pin from ESD, reverse connection, and other possible user error that might cause damages to my circuit. This pin output pulses depend on the amount of water passing through ...
2
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1answer
394 views

P-MOSFET allowed some reverse current, L7805CV destroyed. Why?

I was experimenting with reverse voltage protection using a P-channel MOSFET. I hooked up an IRF9510PBF in the following configuration (diagram from Nick Gammon's site, will change if requested): ...