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Questions tagged [protection]

Ancillary circuitry added to a design that provides protection of the main circuitry to enable the main circuits continuing functioning. In some cases the protection circuitry is sacrificial, being destroyed or degraded in the act of protecting. But not all protection circuits may do this. Examples of faults protected against are: Overvoltage, ESD, overheating, Overloading (too high of a current draw) amongst others.

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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 ...
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92 views

Disadvantage of using a Schottky diode across the LDO input/output for reverse voltage protection

I'm studying a linear power supply circuit design for my future project and I started off disassemblying a good(expensive) LPS out in the market. While I was studying it, there was a part that I wasn'...
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79 views

how to make an ESD sensitive circuit?

I have an experiment where I plug a sensor to an ESD (Electrostatic Discharge) protection circuit. Sensors are very expensive and very sensitive to ESD. I have tested my protection circuit it is ...
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17 views

2S 18650 Li-ion charging module with protection

I am looking for a 2S 18650 Li-ion battery pack module that keeps the cells in check during mainly discharging (I can deal with charging them separately, but it would be nice to have that too). So ...
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54 views

Protecting RS-232 from overvoltages

I am using Some arduinos (5V Pro-Mini, but planing to move to actual ATMEGA chip) over a distance of few metres. These are connected using standard Alarm cable (I had problems with Ethernet cable and ...
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54 views

Smart undervoltage protection

what is the simplest way to regulate the min DC voltage in a circuit? ...
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2answers
188 views

Pre-amplifier input protection

I am building the Velleman K1803 pre-amplifier kit. This amplifier has a maximum input signal of 40mv. The audio input to the pre-amplifier will be a piezo-electric sensor, and this can certainly ...
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21 views

Motor-side of BLAC supply goes into overvoltage when regenrative braking using an LM5060

I am currently using an LM5060 for protection of the motor supply on my BLAC motor driver. Everything works well until I decelerate the motor quickly, this makes the supply voltage peak above the OVP ...
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35 views

Protective-Earthing the chassis with the earthing point being the star-point - How does it keep the Chassis at Earth potential?

I always understood that one of the two purposes of protective earthing is keeping the electric potential difference between the chassis of a devide and the ground (the ground I am standing uppon ...
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39 views

150 A 12 - 16 V DC Short Circuit Protection

I am powering a ROV from a 4S LiPo battery (12.0 V minimum, 16.8 V maximum). The resistance of the battery is 36 mΩ, so that a maximum current of 470 A can flow through a short-circuit. In order to ...
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52 views

voltage transient protection for MV Motors

What types of transient voltage protection is applied on medium voltage motors and are these types of protection that are applied depended on the type of motor it is e.g Synchronous vs Induction motor?...
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1answer
68 views

How does this isolation transformer protect user from transients/mains?

I'm looking at a pretty simple overvoltage/transient protection circuit designed to protect users but I don't understand what the transformer is doing. The circuit is designed to protect the output ...
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66 views

Device for preventing 12V battery from dying

I am looking for a device which cuts off the connection between batteries and the system just like a circuit breaker when my 12V battery goes below 9V(for example) for preventing it from dying ...
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2answers
24 views

How to check protection circuit in lithium battery

I've recently bought a single cell, 600 mAh lithium battery (like this one) and a TP4056 battery charger module, which I intended to use with the battery. The charger has an integrated protection ...
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1answer
42 views

Protection for transistor driving a coil

I recently purchased a few electromagnets. I want to drive these with transistors, but I want to build in protection, as these don't have any available specs re: max operating temp, duty cycle, etc. (...
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1answer
38 views

RTD circuit in industerial application

I'm trying to design RTD measuring for industrial use which has EMI/EMC/ESD. I have 3 wires input to the board. obviously 3 wires out of the board are going to 3-wire configuration PT1000 1- 3V3 (...
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2answers
53 views

±12V protection for MIDI input

TLDR; how to make a MIDI input withstand shorting to \$\pm12V\$? This is a counterpart to this question, I'm asking this as I was inspired by the great answer I got there. I'm designing a MIDI input ...
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2answers
113 views

±12V protection for MIDI output

TLDR; how to make a MIDI output withstand shorting it to \$\pm12\$V? I'm designing a MIDI output in a eurorack modular synth module on a TRS jack (this is a semi-standard non-standard way to save ...
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62 views

MCP73871 Battery Under Voltage Protection

I want to use MCP73871. Is there a battery under voltage protection in this charger IC? or may I use a battery protection IC? Answer for @Bimpelrekkie I decide to use my power architecture as ...
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1answer
122 views

Cause of high failure rate in SC189 buck regulator

I have a small board that uses the SC189C buck regulator to take 5 V down to 3.3 V. For whatever reason somewhere between 25% and 50% of these boards have had the voltage regulator fail at some point, ...
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63 views

What is the difference between these two protection circuits?

I have seen both protection circuits used in various designs. The first just back to back diodes clamping a line, the other clamping the line to the system voltage rails. Whats the difference between ...
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1answer
67 views

Mosfet Gate-Source Zener [closed]

I want to confirm this circuit is going to work and ask how to calculate the zener voltage. The load is going to be driven by 30 volts, and the gate voltage is the same 30v, through an optocoupler.
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1answer
71 views

Op Amp input protection

I was looking for an Op Amp input protection circuit and the most common I found looks like this. When the voltage at Input Signal goes above/below Op-Amp's supply ...
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1answer
36 views

Need help finding an under-voltage protection IC for 2-4 cells [closed]

I've been looking for the last few days but I just can't find one. I've found a ton of single cell protection IC's but I can't find one that does the same for up to 4 cells. A stackable single cell IC ...
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2answers
61 views

Mains AC overvoltage protection using a TRIAC

I am trying to design a circuit that protects 127V appliances if plugged in a 220V socket (in Brazil 127 and 220V sockets have the same shape and it's easy to plug a 127V appliances in a 220V socket ...
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1answer
68 views

Input protection on a DC jack

I am designing an battery powered instrument with around 20-40Ah 3S li-ion batteries in it along with a 10A 3S(12.6v) external charger. Due to ease of availability and the current capacity I have ...
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1answer
38 views

How do I choose appropriate fuse for my circuit?

I am currently using a AC-DC adaptor with specs: AC-I: 100-2040V~50/60Hz 1.6A DC-O: 12V 5A Which is powering up 8 DC motors, 4× 12V 6W 4× 12V (wattage not specified, the motor is meant to be ...
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116 views

How does diode clamp protection work?

I am not able to understand how diode clamp protection works. Considering the diode clamp protection as shown in Figure 1: When the input voltage (Vin) becomes more than power supply voltage (Vss = ...
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1answer
41 views

Power Consumptions of GFCI Outlets and GFCI Breakers

Due to my applications, I need to know the ballpark power consumption of the internal circuit of a GFCI receptacle and GFCI breaker. Has anyone measured them? Could they reach above 5w or 7w?
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65 views

Protecting analog pin from ESD strike

After reading some relevant questions on ESD here, I have come up with the following approach to protect some ADC GPIO pins on my lipo battery operated board that are open to external input, thus ...
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1answer
44 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 (...
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51 views

GFCI contacts with two solenoids

I've finally understood the purpose of the second solenoid in the above GFCI. How it works is when Reset was pressed. The contacts come to the top (attracted by the top solenoid). And in the second ...
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20 views

Low Side Mosfet protection circuit

I build a current limiting circuit, which clamps the current to lets say 4A. Id like to add a mosfet protection, which copletelly turns off the power mosfet, if Drain - Source is higher than 6V. In ...
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1answer
69 views

Voltage sampling from 220vac to 5vdc

I made a 1 phase to 3 phase inverter using arduino and IR2104 to control the speed of an induction motor and it is working perfectly. To complete the protection scheme, I need to monitor voltage of ...
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1answer
71 views

Leviton GFCIs constantly trip on shaded pole motors

Update: I consulted with other electrical engineers. Here is a plausible mechanism. Again refer to the circuit diagram of this GFCI: Look at the board layout. There is a long trace from where C3 is ...
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1answer
41 views

Reverse Polarity Protection with parallel P-MOS transistors

There is a well-known reverse polarity protection technique using a P-channel MOSFET like so: simulate this circuit – Schematic created using CircuitLab If I use the common BSS84 for this task,...
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42 views

How to charge Lithium Ion with protection circuitry

I am trying to build a charger for the Ctr 003 battery for the Nintendo DS. This battery has 3 outputs, which I call +, 0, and - for simplicity. When I measure voltage from + to -, or from + to 0, I ...
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26 views

IT characteristic implementation of motor protection circuit

I am trying to implement The IT - characteristic feature for motor protection device.There are 2C,5C,10C curve feature . can someone suggest me how it can be implemented in C code. Is there any ...
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3answers
844 views

Fuse 125V/4A can be replaced with 250V/4A?

I want to replace a blowed fuse 125V/4A but it is rare to find them. Can I use instead a 250V/4A ? I read at https://www.mojotone.com/support/Knowledge-Base/Is-it-ok-to-replace-125v-glass-fuses-with-...
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1answer
207 views

help understanding this reverse polarity protection circuit

Going through LT4363 evaluation kit DC2062A-B (schematic here), I came across a reverse protection circuitry that protects downstream components from reverse transients and reverse DC voltage: In ...
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0answers
14 views

derive Equation between time and current in motor protection device

I am trying to imperilment The IT - characteristic feature for motor protection device.There are 2C,5C,10C curve feature . can someone suggest me how it can be implemented in C code. Is there any ...
6
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2answers
251 views

Reverse voltage protection for Analog Devices’ family of protection controllers

After going through several datasheets for devices from "Analog Devices’ family of high voltage surge stoppers, overvoltage protection, overcurrent protection, and circuit breaker ICs", I found that ...
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2answers
103 views

Can water condensation appear on PCB in IP67 enclosure box?

Does IP67 box protect PCB from moisture? If not, is it OK to have an outdoor air humidity sensor soldered on PCB in IP67 housing? Also if it doesn't block moisture, is there any reason to use IP65/...
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1answer
67 views

Reducing the start-up voltage of a low voltage cut-off circuit

I just built this circuit, with the intent to use it as a low-voltage cut-off switch for a single li-ion cell. It works great, but once it's triggered it needs about 7 volts to turn back on, so I ...
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2answers
110 views

TVS diodes for Ethernet/PoE?

I am getting confused in selecting TVS diode for Ethernet Interface. Should I connect one bidirectional TVS diode across a ...
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0answers
40 views

Sense coil based leakage current meter (with LCD display)

This is the circuit diagram of the previous Leviton GFCI receptable without auto-monitoring self test. Do you (or others) know whether the current coming out of the sense transformer or sense coil is ...
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0answers
42 views

Testing the presence of GFCI Auto-monitoring Self Test circuit

This is the GFCI IC used: Does it have auto-maintain self test? Here are the internal parts of it. Anyone recognize if it has an auto-monitoring self test IC (or circuit pattern) or something? ...
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2answers
224 views

Can a thermal fuse of a higher rated current be used safely?

I want to replace a 115°C 250V 2A thermal fuse used in a fan motor. The only fuses available locally are 115°C 277V 15A. Can I use the higher current rated thermal fuse? Since it is a thermal fuse, I ...
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36 views

Resetable fuse leakage

I'm planning to use Resetable fuse PTC for cable protection of a sensor's cable. The sensor will not draw more than 40mA. So considering that PTC is not accurate and its affected by temperature I ...
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1answer
237 views

TVS bidirectional diode not working

10x bidirectional diodes 1.5KE400CA in series, balanced, then the chain in parallel for DC line protection. Breakdown voltage 400V per diode. Still got 10kV+ voltage spikes (picture below, x100000 ...