Questions tagged [protection]
Ancillary circuitry that protects the main circuitry in case of a fault. Examples of faults protected against are: overvoltage, ESD, overheating, and overloading (too high of a current draw). In some cases the protection circuitry is sacrificial, being destroyed or degraded in the act of protecting.
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Is it OK to have two protectors for a single Li-ion battery?
I have a question regarding a Li-ion charger/protector module. The board I'm using a fairly standard Li-ion charger/protector module.
This module manages the charge using a TP4056 IC and has a built-...
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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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Residual current relay continuity
Even if the leakage current relay is 300 mA, it cannot provide human protection in such a case. Then, if I make a circuit like this, if there is already 270 mA leakage, then if there is an extra 30 mA ...
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Litium Battery Series-Parallel 2S2P Protection
I am designing a PCB which has 4x Primary Lithium cell Batteries (ER14505M) two in series and two in parallel to give 7.2 V 4400 mAh. The cells have their own holder so it would be possible to only ...
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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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How should I layout an optocoupler isolation board with separate ground references and power supplies?
I am thinking about how to layout my opto-isolation board. It is used to protect pins on an FPGA, convert signals to RS-422 and then transmit via RJ-45.
I have seen some conflicting information about ...
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Snubber circuit protection
I am trying to understand how to implement snubber circuit protection as I have seen different circuit diagrams, I am lost.
Image source: Homemade Circuit Projects - Prevent Relay Arcing using RC ...
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What is the best way to mitigate the spark when a PCB is connected to power?
I'm designing a moderately powerful motor controller (integrated into a product). The board runs on 24V and has a 100uF electrolytic input cap, as well as 2 10uF ceramics near the switcher.
Whenever I ...
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Does ESD protection cause voltage leakage?
I have a this schematic for powering ESP32 over the usb and communicate PC with usb interface. It works perfect. But there is a interesting error. while I am powering ESP32 with Lipo battery (In case ...
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Will relays benefit from protection in form of a flyback diode?
If an inductive DC load is controlled via a relay, would that relay need or benefit from a flyback diode for protection from the loads off switching voltage spikes?
Note that this is not about a diode ...
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Correct way of optical input EMC protection
I tried to find an answer online, but didn't find anything that would make my doubt go away.
The thing is: when you want to protect any input, that is referenced to ground, you use ground-referenced ...
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Rating of circuit breaker for protection
This circuit breaker is rated as 12V-48V 100A and I have to use this circuit breaker between additional alternator (24V 100A) in my vehicle and additional battery bank to provide overcurrent/short ...
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How to predict the voltage drop due to a fuse?
My device runs from a USB supply, typical 5V, current typically 20mA, never beyond 100mA.
I want to add a fuse. The JFC0402-0500FS claims rated current 0.50A (perfect for this application) and a ...
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Does a modern voltage regulator provide reverse polarity protection and other protections?
I'm powering my circuit from 5V USB. Since USB is already regulated, I don't need a voltage regulator.
Will adding a modern regulator like L78M05C offer protection (besides regulation)? Concerns:
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Measuring capacitance with NE555 in astable mode
I have one problem with my project. I trying to measure capacitance with NE555, but i have problem with protection.
In this schemeatic instead of a capacitor, I have put connection socket 01x02 for ...
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Digital Input Voltage range selection
I am designing 24V industrial shields with 4 channel Digital Inputs. the digital inputs voltage range shall be set by 1P3T switch wherein the switch shall be actuated between 3 voltage ranges of 0-24V,...
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Protecting parallel 18650 cells
My son is doing an Eagle project where he is creating a solar charged LED light set up using two 18650 cells in parallel. We are working to ensure they are safely protected. From the research we have ...
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Ethernet PHY ESD protection, difference in components
I'm using a Würth Elektronik 7498210220A jack (datasheet) and I need to add ESD protection to TD and RD lines of this Ethernet connector (with integrated magnetics).
Application of this Ethernet ...
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2S Li-ion charger+protection with reverse protection
I'm designing a device powered by two Li-ions in series and I'm struggling with the charging and protection of the batteries. One of the requirements is to avoid battery packs, the individual cells ...
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Why does AS3001:2008 Transportable Structures explicitly deny a separate earthing electrode?
As the title says, if a generator is providing a TNS earthing system connected to a transportable structure through a detachable connection, why does AS3001 state:
Isolation of the protective earth ...
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TN-S Earthing parallel return paths when multiple MEN links
I have a bit-of a unique situation. I have a generator which is running a TN-S earthing system. It is powering demountable offices.
I assume that all sub circuits would have RCDs in the demountable, ...
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USB ESD Protection with the NUF2042XV6T1G IC
I have been trying to figure out how exactly I should connect the NUF2042XV6T1G IC to my USB data lines. From what I understand, usually a reverse biased transile diode is connected between the data ...
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Implement adjustable overcurrent protection for DC current
I am designing a hobbyist's multi-fixed voltage channels using ATX PSU breakout.
Of course the fixed voltages are 3.3V, 5V, 12V, and if possible, -12V too which are supported by ATX.
Now I want to ...
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Arrangement of this diode
I am using this diode for a protection of a bidirectional line. I want to protect the line for both positive and negative transient. But struggling to find the connection to make sure the diode helps ...
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Help to understand this 5V relay module's diode
Hello people, I need a bit of clarification regarding the below module, especially with the diode that is used. Does anybody know the value of it? If it is 1n4148, is it a Zener diode? What will be ...
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How to use blade fuse in DC circuit as protection?
While trying to add a protection to my buck converter circuit I came across Blade Fuses, which are faster at breaking compared to glass cartridge from what I saw. The question is, how is such a fuse ...
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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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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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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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Intentionally cutting off an audio signal at high volume
TL;DR: I am looking for a the best way to amplify all external sound but cut off at a hearing safe level.
I am attempting to incorporate active ear protection into an old SPH-4 helicopter helmet. I ...
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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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How and where to learn protective relaying for power systems?
I'm trying to learn protective relaying for power systems. More specifically, I want to learn how to calculate the settings that must be configured in the digital relays in order to build ANSI device ...
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I'm making a development board for ESP32 S2 board, I want to achieve IEC61000-4-2 (level 4) ESD protection on the connectors
I am using a 4 channel TVS(diode) array that has a max clamping voltage of 12V. I have a voltage devidor to translate 5V to 2.5V. So I asume that max clamped input is 6V if an ESD event occurs.
I read ...
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Protection of my loads (batteries + equipment) from alternator
I have an aftermarket additional alternator (24v, 100A) installed in vehicle without external regulator (don't know about internal regulator). I have found this alternator locally probably used ...
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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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Can this circuit limit power surges?
This circuit I had created based on MOV and a relay, it principle is: if a surge comes the MOV would get activated and should turn the relay thus the surge should be redirected.
Notes:
Input is ...
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How to put a decent snubber to the MOSFET?
I am trying to make a soft starter for an inverter to make the turn on process as a yield curve like the one in the photo:
so I used this circuit :
however, the problem is still visible in the turning ...
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Charging voltage across VM and VSS of AP9221SA-CC-HAC-7 is 0.6V even when USB charger is inserted
I am using AP9221SA-CC-HAC-7 PCM IC with 1-cell Li-ion battery (4.2V). I have battery charger (RT9471) after PCM IC and load connected after battery charger. The PACK+ and PACK- signals go the the ...
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PMIC using AP9221SA-CC-HAC-7 not allowing charging
I am using AP9221SA-CC-HAC-7 PCM IC with 1-cell Li-ion battery (4.2V). I have battery charger (RT9471) after PCM IC and load connected after battery charger. The PACK+ and PACK- signals go the the ...
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R5613L understandig what MOSFET to use
I want to add a battery-protection to my circuit including a switch to disconnect the battery from the rest. I found the R5613L from Nisshinbo (Manufacturer product site with datasheet).
On page 26, ...
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Busbar short circuit rating vs. cubicle rating
First: This question is about medium and high voltage switchgear, not electronics.
A 7,2 kV switchgear has a short circuit current rating of Ik = 40kA/3 s. The ...
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What will happen if I choose a higher value capacitor for ESD protection than the recommended value?
I want to protect my circuit from ESD, for which I have chosen a capacitor as ESD protection due to size and cost.
I have chosen a KEMET 1000 pF 16V with 25 kV breakdown voltage capacitor value ...
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Protection for unpowered ADC module
I'm trying to measure a low frequency (0.1 - 100 Hz) signal with an ADC module. After powering the sensor up the signal can have common mode voltage from -15 V to +15 V and is tuned manually (the ...
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Reverse polarity protection: pros/cons fuse+diode vs. latching MOSFET
I want to add reverse polarity protection for a battery charger ic.
What would be the pros/cons with the two circuits attached?
EDIT: the fuse will be a resettable (PTC) fuse.
The circuits have been ...
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Protecting DC power supply from accidental mains connection
Is there a way to protect a DC power supply from accidental mains connection on its outputs?
Edit: The protection should not require any service i.e. a fuse replacement. Protection should kick in when ...
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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 ...
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Lithium Battery Protection DW01
I'm using DW01 to protect LiPo batteries. But since there are more than one source of voltage in the circuit, I need to add a diode to DW01's VCC pin for the situations that battery is removed and ...
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Protecting from ESD only with resistors and BAT54
I have a device with too many external contacts exposed to ESD, I search for a way to reduce cost of ESD protection.
According to datasheet BAT54 can stand 1 A non-repetitive peak forward current. So ...
