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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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Protection still adequate?

I'm trying to protect an analog input (that goes through a MUX and a buffering op amp). Expected input frequency is less than 10 Hz. I would like to go from the top schema to the bottom one. LDR/...
user1532080's user avatar
1 vote
2 answers
88 views

How to protect a motherboard from an old power supply? [closed]

I have an old Taiwanese Senstron ST-41 (TAO YIN-TCY6 94V) power supply from 1987 used in an Apple 2 clone with DC outputs: 5V 5A 12V 2.5A -5V 0.5A -12V 0.5A Is it possible to add extra protection (...
Anton Andreev's user avatar
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7 answers
1k views

Does it matter if a fuse is on a positive or negative voltage?

I have a power supply with -5V DC output. Can I use a fuse 5V 0.5A for this -5V rail as if it was 5V 0.5A? The rail I want to put a fuse on goes into the motherboard. The motherboard does not have any ...
Anton Andreev's user avatar
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1 answer
49 views

Type of diodes for 9V [closed]

I am looking to protect a 9v battery against a 12v battery. I know the question has been asked already and someone did put a circuit up as well but I don’t know what type or what model number I need ...
Sajhid Buckreedun's user avatar
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1 answer
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Jump on varistor I/V curve when "passing" through max. leakage current region to max. clamping voltage region?

I'm taking a course on semiconductor physics and another on something like "usage of electronic devices". On both I've come across the I/V curve on a varistor, this is: I cannot find the ...
Vito P.'s user avatar
1 vote
1 answer
77 views

Modelling a Desaturation detection circuit on LtSPICE

I am trying to model a gate driver desaturation detection mechanism with discrete elements on LTSpice. The waveforms I have obtained now provide a constant Vdesat of about 5.6V when MOSFET is turned ...
Agniva's user avatar
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2 answers
69 views

Ensuring Proper Damping and Protection at Power Connector Inlet

I am designing a power input stage for a system (which consumes up to 90W) and want to ensure it is properly damped and protected. Here are the components and considerations I have incorporated so far:...
Firas Abd El Gani's user avatar
1 vote
1 answer
60 views

How can I protect a DC/DC converter when VIN is floating?

I'm using a L6902 (https://www.st.com/resource/en/datasheet/l6902.pdf) to charge a 4 cell lifepo4 pack (with a solid BMS). Do I need a diode on the converter output (PACK+) to prevent the converter ...
alexlroemer's user avatar
5 votes
2 answers
168 views

Well protected digital input with long wires

I've created simple circuit to protect MCU's digital input against eg. induced spikes. I want to connect quite long wires to this HW and highly probable that this board will be placed close to the ...
szymo092's user avatar
2 votes
1 answer
90 views

High-Side NMOS Short Circuit Protection: How to Calculate Maximal Allowed Turn-off Time?

I'm about to build a high-side MOSFET switch that can switch voltages up to 150V to an external load (0.5A nominal). For this application I would like to use the N-Channel MOSFET Vishay SiHH240N6E. ...
Mau5's user avatar
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Troubleshooting a Low Voltage Cutoff (LVC) Circuit for Overdraining Prevention

I am attempting to design a Low Voltage Cutoff (LVC) circuit to safeguard against overdraining my 12V rechargeable battery. The objective is to halt circuit power once the battery voltage drops below ...
Karampistis Dimitrios's user avatar
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0 answers
15 views

Ideas for protecting an sEMG system from external problems

I am designing a pcb to work as a human-machine interface. Here is the simplified schematic: The idea is to connect a custom sEMG acquisition system to esp32 and also a pcb to control vibrotactile ...
pedro ulhoa's user avatar
0 votes
1 answer
81 views

Will voltage at the inputs/outputs destroy an unpowered opamp?

I have a circuit powered by 12V that accepts an input signal of 0V to 10V. The circuit shall act as a buffer to the signal, with an added LED indicator. In certain circumstances, the circuit itself ...
one_three_three_seven's user avatar
2 votes
1 answer
51 views

Protection circuit for a 12 V Li-ion battery pack

Is there an integrated circuit or a conventional circuit topology to monitor edge conditions of a 12 V battery pack without measuring individual cells within that unit? A conventional BMS or battery ...
lucenzo97's user avatar
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1 answer
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3 pin Gas Discharge Tube (GDT) - pinout order

I would like to know the reason behind the pinout order of a 3 pin GDT. GDTs are designed to prevent damage from transient disturbances by acting as a “crowbar” in creating a short-to-ground circuit ...
Jjeico's user avatar
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1 answer
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One-Way charging connector for 4S Battery

I want to use a connector to charge the 4S Battery of my underwater robot. The connector is the 6 Pin hybrid Cobalt Series connectors from BlueTrail Engineering (https://www.bluetrailengineering.com/...
Teusner's user avatar
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4 votes
4 answers
644 views

How to prevent this op-amp from railing

I have the following circuit: An input that can go negative (+/-5 V sine wave), and two inverting op-amps. The second op-amp is "current buffered" and is driving the base of a BJT. Here is ...
DarkBulle's user avatar
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0 answers
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What are the meaning of the simple directional arrow above the double arrows in this schematic?

Helo,, I would like to know what are the simple directional arrows above the double arrows in this schematic?.
Daniel Prieto López's user avatar
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0 answers
75 views

Protecting negative power rail

I don't trust my power supply and want to protect my circuitry from over(under)-voltage, but cannot find a clear path of going forward with negative power rail. LDO which I use (LT3094) is rated for ...
Andrejs Cainikovs's user avatar
1 vote
4 answers
125 views

Risks of placing Varistor before Fuse for Mains Voltage

I have seen many questions on this and other forums asking about the best option to place the fuse relative to the varistor to protect it from mains voltage spikes and the answer was unanimous: The ...
Dinis's user avatar
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2 answers
61 views

How to select ESD TVS diode? [closed]

This is the following specification of my circuit Vin 8V to 32V The breakdown voltage should be 33V of TVS I don't know what clamping voltage means please simplify it for me What should be Vc?
Monesh Rathod's user avatar
1 vote
1 answer
61 views

Protection from live casing without true ground

I guess my question is probably trivial with an expected answer like 'It couldn't exist and would be dangerous', but still I keep it around. Could you build a protection circuit that would protect a ...
Simon Lang's user avatar
0 votes
2 answers
101 views

How does a voltage surge/spike affect the wall wart power supply's secondary side?

In the photo, you can observe an old-style adjustable wall wart AC to DC power supply, typically composed of a primary winding, secondary winding, rectifier, and capacitor. If a voltage surge or spike ...
xchcui's user avatar
  • 299
6 votes
2 answers
631 views

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 ...
ThreePhaseEel's user avatar
1 vote
1 answer
60 views

How is SM712 TVS array suitable for use with MAX485 in an RS485 driver circuit?

I have an RS485 driver circuit consisting of a MAX485 driven by an STM microcontroller. I was looking at TVS diodes for basic protection from electrostatic surges from wiring and handling, and found ...
nottherealfaraday's user avatar
1 vote
2 answers
172 views

Operation amplifier input HV protection

I have a setup consisting of 8x AD8428 ultra-low noise opamps on a PCB to measure very small voltages with a noise floor of around some 100uV and a low-pass filter up to 10kHz. The input is connected ...
NNN123's user avatar
  • 103
0 votes
2 answers
54 views

Mains transformer input overvoltage protection

You have a mains transformer with switchable inputs, 120V and 230V. In case somebody switches the input to 120V and applies 230V (which cannot be mechanically prevented, reasonably), the whole ...
Michael B. Ortiz's user avatar
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0 answers
11 views

What does the graph 'Short circuit monitoring interval Vs time' mean in this SSR data sheet?

In one of the Panasonic Solid State Relay (SSR) datasheet,the short circuit behaviour is as shown below : If short detected- > Trip the relay -> Periodically retry untill the fault is cleared. ...
Dynamic_equilibrium's user avatar
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2 answers
97 views

Not able to correlate the graph and table for the I2t rating in a fuse datasheet

In the datasheet, the I2t rating of a 5A fuse is 0.055 at 10 times In. Using the same value to estimate the trip time for the 10 A condition, I get 0.0022 seconds. In the graph below, it comes ...
Dynamic_equilibrium's user avatar
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What do the following parameters indicate in a resettable fuse?

I am not sure how to decipher the Pd and R1max info in the below datasheet. Does PD indicate the tripped state power dissipation or maximum power dissipation under non-tripped operation? If you ...
Dynamic_equilibrium's user avatar
0 votes
1 answer
55 views

What is the criteria to choose between PTC thermistor and resettable fuse (PPTC)?

Wiki states: (PPTC) are similar in function to PTC thermistors in certain situations but operate on mechanical changes instead of charge carrier effects in semiconductors. Another wiki says there is ...
Dynamic_equilibrium's user avatar
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0 answers
50 views

DC Bias network for a LCR meter

I am trying to make a DC bias network for my LCR meter (Scientific SM6023) based on this circuit I found online RD10E has a Zener voltage of about 10V and 1N4004 has a forward voltage of 1V. I have ...
amogh waghmare's user avatar
2 votes
2 answers
91 views

Dual Rail Reverse Protection Circuit for OP AMP inputs

Is there a way to resolve this? When wrong polarities is applied,then I wanted no voltage or current flowing towards the OP Amp. Thanks!!
HuracanWind's user avatar
0 votes
1 answer
100 views

PSPICE non sinking voltage source

In an ideal world, most power supplies have a current sourcing feature but not a sinking feature. In this circuit, you can see that the 15V supply is sinking current. How can I prevent this in Pspice?
Electronx's user avatar
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0 votes
1 answer
107 views

Arduino Uno ESD ruggedness

I want to route one of the Arduino's digital output pins out of a device, to interface with other instruments via a several meter long coax cable. Typically, I would implement measures against ESD for ...
tobalt's user avatar
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1 vote
0 answers
48 views

Issues with AP9101C Lipo protection IC and the auto-wakeup feature

I'm developing a pcb for a product powered by a single-cell li-ion battery. Since I couldn't find an appropriate battery with a built in protection ic, I decided to add one to my design. After ...
Marcel Król's user avatar
2 votes
3 answers
271 views

Ferrite bead value for a LIN bus protection circuit

What is the proper value for FB1 in relation to the surrounding capacitors in this diagram? The FB1 resistance is measured to 0.76ohm and package size is 0603. All components are AEC-Q200 rated. The ...
ajdalshov's user avatar
1 vote
1 answer
117 views

Auxiliary mechanical anti-ESD measures

If a PCBA within a plastic enclosure is prone to malfunctioning due to ESD air discharge in proximity of enclosure seams and openings, but changing the hardware or plastic design is not an option, ...
NoobPointerException's user avatar
1 vote
1 answer
75 views

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-...
Stijn's user avatar
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0 votes
0 answers
80 views

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 ...
Gigapel's user avatar
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1 vote
1 answer
51 views

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 ...
Jundullah's user avatar
  • 111
0 votes
1 answer
68 views

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 ...
Mike's user avatar
  • 1
2 votes
1 answer
277 views

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 ...
Gigapel's user avatar
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1 vote
1 answer
253 views

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 ...
Friizzle's user avatar
2 votes
2 answers
162 views

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 ...
Khales Naim's user avatar
3 votes
2 answers
381 views

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 ...
Drew's user avatar
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0 votes
2 answers
87 views

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 ...
mehmet's user avatar
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1 vote
3 answers
131 views

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 ...
MiNiMe's user avatar
  • 1,609
1 vote
2 answers
142 views

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 ...
Maks's user avatar
  • 43
0 votes
1 answer
41 views

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 ...
James Ross's user avatar

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