Questions tagged [circuit-protection]

A device, components, or safety measure designed to protect circuits from overvoltage, overcurrent, a combination of these; or the theory of same.

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22 views

How can I wire the MyoWare and FSR sensors with the ADS1299 ADC?

I am using 2 Myoware sensors to measure the EMG signal and 8 FSR sensors to measure the FMG signal.For analog to digital conversion I am using 2 ADS1299 connected ti raspberry PI.I am now making the ...
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35 views

How can I improve the common mode rejection ratio for TI ADS1299 ADC?

I am using 2 TI ADS1299 (home page, datasheet) devices with Raspberry Pi4 and I want to improve the common mode rejection ratio. I don't understand the proposed techniques such as the isolation ...
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Over voltage protection circuit for Iphone devices

All powerbanks I have found are able to provide 5V, which is perfect for android smartphones, but not for Iphones, which have a nominal voltage of 3.8V. However, powerbanks of 5V may be used to charge ...
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47 views

Would this design for Li-Ion cell protection+balancing circuit work?

My team and I are currently trying to design a 2S2P battery pack for use in a CubeSat (student project). The pack is planned to be used with 30-40% depth of discharge for a total of around 5800 charge-...
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39 views

ESD Protection Diode: I/O Protection on VBUS Line instead?

I'm looking at a few 4 channel ESD diodes for my USB circuit, specifically the ESD0524P and the PESD2ETH-X. For my circuit, I only need 2 channels, D+, D-, and a channel for VBUS. Looking at these two ...
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88 views

Type-C Non-Negotiated Power and 20V protection

I'm developing a 5V device and I use 5V for powering/charging the device. I googled the subject of course, and came to the conclusion that 5V device should have 20V protection in case there is some ...
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28 views

Do I need OD/OC/OV Protection for Small LiPo Batteries with a Protection PCB already?

I'm building a small design that is designed to only take smaller LiPo packs, those that often terminate in a JST PH 2.0 connector with example below: It seems like most of these similar batteries I ...
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1answer
53 views

Why location of CT is different for the two Circuit breakers in same substation layout?

This is a schematic diagram of a traction substation. In this traction substation protection system schematic diagram, at point marked 'A', CT is located after the 25kV CB. However, at point marked 'B'...
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Protecting RPi against lightning and high voltage

I'm making a remote weather station with a Raspberry Pi 4 and a few sensors. Problem 1: the anemometer is held on a iron rod (was already there, can't change), dangerously exposed to lightnings. ...
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33 views

Wiring problems on the TP4056 Module

I have been thinking of putting a 18650 Li-ion battery salvaged from an old laptop power battery to use so, I bought a few of those cheap TP4056 battery protection and charge circuit modules and I am ...
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What is the use of this diode in the circuit?

What is the use of this diode in the circuit? I guess it is used for short circuit protection and turning off the LM2576.
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Battery and External Power without Diodes Circuit

I'm designing a power system for my project. My project is powered from standard 18650 li-ion battery (or other 3.7V battery) or from USB 5V power source. Originally, my requirements were broader, I ...
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Host and device protection needed for designing for USB type 3.0 powered electronics?

I am designing a switch-mode variable power supply (that can boost) intended to run on USB type 3.0 (be powered by a PC/laptop USB port say). Being that I am quite naive to computer electronics I am ...
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42 views

USB supply protection using shotkey diode

Here is the atached schematic of the clamping diode condition. Isolated the connection to contoller and kept the end open. When USB input is varied above 5V the expected output is diode cathode ...
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2answers
52 views

Controlling AC motor with relay vs. switch on motor

Is there a difference in terms of operation between switching a relay connected to mains for an AC motor versus opening/closing a switch on the motor? Would the internal protection circuitry ...
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DC isolation fault circuit breaker feasibility - design review

So I was wondering what the best way is to interrupt ground faults in ground isolated DC circuits. After some research, I found out about isolation fault detectors and was wondering if one could use a ...
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48 views

Capacitive AC to DC power supply noise

Im using a transformerless capacitive power supply with this simple circuit: C1: 3.3uF 400V R1: 480K D1-D4: 1N4007 Z1: 10V 1W C2: 470uF But it burned some my ...
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I am trying to measuring leakage current from motor and driver and identify which part contributes more leakage and then to improve it

From UL standard, if I only want to measure a part of device's leakage current to another part. I can just measure the Grounding wire. So I used a clamp on meter (0-10mA range) to clamp on grounding ...
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43 views

What is the RMS current going through this fuse?

I'm chose a fuse to for a transformer, and now I'm trying to calculate the cross section of the cables. I'm using the following formula: Where Tk is the protection time, Ik the short-circuit current ...
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38 views

reverse polarity and low voltage protection circuit proposal

I'm designing my own li-ion single cell protection circuit, whose requirements are the following: Shall be protected against reverse polarity Shall disconnect power whenever the voltage battery is ...
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80 views

Fuses & current ratings - are there fuses that blow “fast” close to their nominal rating?

The context or reason for this question is the following: Reminder: the question is about the fuse, not about the TRIAC. The context may help to understand the question. A 230V output is controlled ...
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20 views

Automotive Load-dumps, ISO standards & Meaning behind datasheet

Im looking towards using an system basis IC for one of my designs (UJA1164A) and i noticed that under the features & benefits it notes that "Battery and CAN bus pins protected against ...
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33 views

Safety considerations (for parts) for a beginner building with expensive parts

I'm building for the first time (for me) a circuit with an expensive part (a $80 DEC J11 CPU) and would like to know some "safety" tips so I don't inadvertently destroy the thing while playing with it....
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Protect MOSFET gates in audio amplifier

I've made an amplifier from a circuit I found on the internet (below, link). I made it more or less exactly as described (same components, big heat sinks) and it seems to work great (can run at a loud ...
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28 views

Do I need to ground this circuit board inside my 3d printed case?

I bought a microphone amp system that has 2 mics and then outputs the audio via aux cable. I am using it for a project and 3d printed an enclosure for it and took out the circuit board from the ...
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71 views

Protect Op Amp input from piezo sensor overvoltage

I have a circuit that I'm using to detects "knocks" using a piezo element. It seems to work adequately, but as I half suspected, I have now demonstrated that it's possible for the piezo element to ...
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27 views

What causes a varistor to have low resistance when connected to a board?

I was inspecting the control board on a non functioning opener motor, there are no visible blown out components. No skid marks. I went to testing conductivity on the fuse component, good across there. ...
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44 views

Low voltage cutoff

A while back when I ordered a 3S Li-ion protection board I didn't think about low voltage protection so I made a small circuit using an opamp. Is this gonna be good or will the magic smoke escape?
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51 views

Why does this N-channel MOSFET not turn off?

I was playing around on CircuitLab to see if I can add an overvoltage cutoff to the reverse voltage protection circuit in TIs slva139. Using a zener, I expect OVS to start rising beyond the zener ...
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75 views

Will high inrush current (30A/115V) trip a circuit breaker?

I was going through some power supplies for my LED Lighting project and found an inrush current of 30A/115V in the datasheet. My questions are: Will it trip my home circuit breaker? How long does ...
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68 views

Protect DC circuit from AC

First and foremost, I would like to point out that I am a beginner in electronics. I have designed a board that is meant to be connected to 240V AC. However, there is a relay on it that has a 12V DC ...
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64 views

Difference between single circuit and double circuit transmission line protection systems

I'm doing a research on long three phase transmission line protection systems and I found many schemes such as distance protection, merz-price voltage balance system, split-conductor, "translay" ...
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81 views

Circuit review: Switch/monitor 12V devices using a USB-connected microcontroller

I've designed a board to allow my desktop computer to switch external USB hard drives on and off. I don't have a huge amount of experience with circuits like this one so I'd like to get some feedback ...
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46 views

Connecting LiPo Battery Protection Circuit Modules in Parallel

I'm working with three 6S very high capacity LiPo batteries (22000mAh each) and I've designed a power circuit that implements them in parallel to provide 25.1V to the load when fully charged. I've ...
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39 views

Detect continuity in AC line during load shedding and take action via DC circuit?

I'm a noob. I have asked another question in this forum, but in component level. As the answer of that question says to use 12v and 5v relay. I reached out to local electroni6c market. But for covid-...
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63 views

How to protect/enhance an LDO so that it can sink current in the event of an external wiring fault?

Background I'm designing a signal acquisition board and one of its parts has several differential op-amps which are not very good from PSRR standpoint. So they need a very clean power supply, and ...
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59 views

I'm looking for a circuit breaker that interrupts the circuit when current drops to zero

I am looking for a switch that only keeps contact while current is running. Once the current drops to zero the switch opens contact. Something like a circuit breaker that trips with no current. It ...
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59 views

Always plugged in solution with battery backup

I am trying to design an micro-controller based solution which is always plugged in and has a battery backup in case of power failure. I am using an SMPS power supply rated 15V, 1.4A which is always ...
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78 views

Voltage protection with 555 timer not working

Briefing I am using Multisim to simulate a circuit before building it. The voltage protection circuit with a regulator works fine and the timer circuit works fine as well separately. When I try ...
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47 views

MOSFET Gate-Source voltage in protection circuit

I'm creating board which is supposed to withstand OV/UV and reverse voltage. I've chosen LTC4365CTS8#TRMPBF(datasheet) IC to deal with this problem. In reference schematic for 24V input they are using ...
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37 views

Protecting ADC pin from the opamp output

i am working on a design circuit and i have to measure the current going through the loads so i put shunt resistor 0.1ohms and from the terminals of that resistor to an instrumental opamp, then to ADC ...
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1answer
62 views

Buck regulator maximum supply voltage VS. voltage spikes at input where we have a TVS diode

Currently I'm using a buck switching regulator AOZ1284PI of Alpha & Omega Semiconductor to generate a 5V supply from a 12V input of a lead-acid sealed battery, and I plan to use AOZ1284PI again on ...
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66 views

How do protection diodes work?

There is something I don't understand with protection diodes. I am talking about a series diode between the + and the load of the circuit to prevent damaging components when there is a wrong polarity ...
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3answers
292 views

How is the 741 op-amp output protected when shorted to V+?

I have completed my answer to the question about the Widlar's limiting circuit but there is something unclear to me - how the transistor Q22 manages to limit the load current when the output is short-...
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54 views

How to protect an externally connected PT 1000 sensor

I have following circuit reading an externally connected PT1000 sensor. The Sensor is on a cord, the side we are looking at in the schematic uses a a female connector. So the pins are not easily ...
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1answer
68 views

Solar charger for Lipo battery

Im trying to build a little solar charger for a Li-po battery using 2 solar panels rated at 6V/120mA a linear charger based on the TP4056 chip The idea is to connect the two panels in paralel so ...
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28 views

Inverse time lag relays in protection

I'm dealing now with the different types of time responses of electromechanical relays: instantaneous, definite time lag, inverse time lag, and inverse definite minimum time lag. My question is: What'...
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21 views

Low resistance fuse selection for BMS voltage tap

I want to put inline fuses on the voltage taps of a battery bank I'm assembling. The BMS (Orion Jr) documentation requires a fuse with current rating of no more than 3A for the voltage taps, and ...
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64 views

Why is the maximum voltage of a surge, 6kV inside home wiring?

I was reading about the benefits and cons of series mode surge protectors vs MOV-based surge protectors for home use. First, why is the probability that a surge will exceed 6kV extremely low due to a ...
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3answers
88 views

Overcurrent protection in lab bench power supplies

In my school we used lab bench power supplies all the time as it is an electrical engineering school. Can someone point me in the direction of an implementation of an overcurrent protection found in ...

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