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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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17 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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1answer
46 views

Can a ground fault be caused by something outside the home?

Yesterday afternoon, I had a GFCI switch trip. It would not reset. I figured I had a ground fault. I left the home for a few hours and after I returned I was able to successfully reset the GFCI. The ...
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2answers
88 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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1answer
29 views

Opto-coupler to convert current into voltage

I am using TPS26601 for my next design. There is a pin IMON which outputs current proportional to current flowing throwing the output pin. The gain ranges from 72 ...
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0answers
19 views

TPS26601 Industrial eFUSE Circuit Design

I have been designing a circuit for various Power protections like overcurrent, overvoltage, ...
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1answer
33 views

74LVC and similar… can a logic 1 output sink current?

Say I am running my 74LVC125 at 2.5V. At the A input I have a logic 1 and at the nOE input, I have a logic 0, so the device should be driving a logic 1 onto the Y output. With no load connected to ...
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3answers
52 views

Single Cell Battery Protection ICs

I'm designing a product that will be powered by a single 18650 cell. Specifically, I am basing my numbers off this cell in particular: Samsung INR18650-25R It has a typical full voltage of 4.2V ...
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1answer
54 views

high power - overvoltage protection

I am designing a circuit to protect a load from over-voltage. The voltage at the load must be around 380VDC and the current consumption will be around 2A. In normal operation the Power Supply must ...
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3answers
95 views

Best way to protect a MOSFET from overcurrent

I'm trying to build the circuit in picture above. unfortunately the load on high side of the step up transformer is unpredictable and the input impedance of transformer is very low so I'm guessing the ...
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2answers
32 views

Battery powered circuit protection

I’m just curious what kind of protection you would typically expect to see on a battery powered circuit. Circuit in question is a simple 24v dc relay controlled motor. Main power source would be 2x ...
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1answer
38 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 ...
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1answer
60 views

How these two diodes used in the ciruit protect from the voltage spikes?

I'm playing around with a simple DIY project, and after about three days of googling and reading stuff I still can't wrap my brain around two Schottkys below: From the project page: The two ...
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0answers
32 views

Testing eurorack input protection

I'm building a eurorack synth module, and I'm about to do the final tests on the design to make sure that the module cannot be destroyed (electronically, using what's available in the rack, so ...
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2answers
44 views

ESD diode selection based on VCC of the IC

I have a question about TVS diode selection. This kind of question is already discussed in previous questions. ESD Diode - GPIO Microcontroller Selecting a TVS for ESD protection For protecting vcc ...
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1answer
48 views

In a DC circuit, are there any reasons for wiring overcurrent protection such as fuse or pptc PHYSICALLY near the load?

In a DC circuit, are there any reasons for wiring overcurrent protection such as fuse, pptc, etc.... PHYSICALLY near the load(or inside it)? By wiring "physically near", I mean in the power wire going ...
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1answer
49 views

Protect signal from noise in Arduino

I am trying to send a signal from the Arduino to a relay to open a switch. My problem is that my Arduino will be near the AC power lines. I searched for how to prevent the noise to ruin the signal ...
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7answers
2k views

Opinions on what I've come up with for a 12 V-to-5 V automotive circuit?

Is this a solid solution for an automotive 12 V-to-5 V circuit to power an ATtiny? I've been trying to come up with a solution for my needs that can handle the automotive environment that is so scary ...
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3answers
115 views

How long do I have before my sensitive components get fried?

I'm using this IC (https://www2.mouser.com/datasheet/2/609/ADM1270-878589.pdf) to control the current and the voltage on some of the outputs of a PCB that controls the power to other PCBs, which have ...
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3answers
136 views

How do I get 5V 10A output from a 3.7V li-ion battery for 64x16 led matrix display module?

Please I am new to electronics and new here. I'm doing a project which involves the use of a 18650 li-ion battery (or two as may be the case) to power a 64x16 led matrix display module which (...
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1answer
57 views

Triggering of TRIAC for Crowbar Protection

I am reading the datasheet of TRIAC (T1235T-8G). I am not sure how to trigger the TRIAC and what do they mean by ...
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0answers
38 views

Is it a bad idea to connect two Li-ion batteries in parallel? [duplicate]

Suppose I have two Li-ion batteries for smartphones. One could say that if they are connected in parallel, then the voltage given to the device would be the same, but the capacity would be doubled, ...
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1answer
94 views

PoE and Adapter Power Supply Design

I am designing a power supply cicruit. The circuit will get it power from PoE (preferably) and external adapter (7 - 12V). For ...
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2answers
98 views

This is very confusing [closed]

Why does it hold the voltage constant? Isnt it supposed to act as a ideal diode during forward bias ie behave as a closed switch?
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2answers
122 views

Inductive load shorts power supply

I had a hair-brained idea the other day and put together the attached circuit. The problem: the instant I push the switch to place a voltage across the inductor, the power supply shuts down. Clearly ...
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1answer
68 views

Fire danger when using IoT components

I am automating my house using components like ESP8266, 220 to 5V converters, relays etc. How big is the risk of a fire starting from a component malfunction and how can I mitigate this? What should ...
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1answer
75 views

Calculating energy of transient/surge handled by metal oxide varistors (MOV) or surge suppressors?

As I get to know more about the MOV operation, there are more things needed to understand. My MOV (V420La20AP) has Varistor voltage of 680 Vrms (10%) at 1 mA, and maximum clamping voltage of 1120 V ...
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1answer
69 views

When to use a 2 pole circuit breaker over 1 pole

We are currently designing a product that connects to 230VAC mains power (single phase) (South Africa). It has a simple 12v switch mode power supply that runs the electronics. We want to put a Circuit ...
1
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1answer
118 views

Full Load Amps vs General Purpose Amps

http://www.carlingtech.com/sites/default/files/documents/M-Series_Details_%26_COS_021114.pdf This circuit breaker have two different current ratings, depending on amperage range: Full Load Amps and ...
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1answer
39 views

Wiring Up a Li-Ion Battery (Band 2)

I have a Li-ion battery that I pulled from a MS Band 2. It comes with a protection chip, which I am having trouble with. The chip has 4 accessible pins, labeled "P+, K, T, P-". I've tried every ...
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1answer
110 views

What is Metal Oxide Varistor (MOV), meaning of its specification and how it protects circuit from over-voltages?

Hello, I have a circuit in which a voltage source is connected to some sort of RC Load. To protect this circuit , there is an Metal Oxide Varistor (MYN15-681K). The Pics of circuit and datasheet ...
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0answers
61 views

How to protect a buck DC-DC being backfed from the load (e.g. a battery as a load)?

Background I want to design a DC-DC adapter that is foolproof and has some protections in place so that it doesn't accidentally damage the somewhat expensive equipment downstream. Here's what I have ...
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1answer
54 views

Can high power USB destroy older devices? [duplicate]

My brand new pair of bluetooth headphones stopped working after charging them with a 2.1 Amps USB outlet. I can't turn it ON anymore. I do see the LED battery Green then I charge it though. I noticed ...
2
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0answers
64 views

High power / high current clamping circuit

I am looking for ideas on how to clamp high energy surges in the input of a high current / high power system. The input to the system is 24V. During steady state, the system sources 85A of current ...
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3answers
98 views

What can happen with the PCB foil while SMD resistor destructive overheat?

I need to protect the gate driving circuit by putting the resistor between the gate and the control circuit: During the testing of the mockup MOSFETs can go be destroyed which leaded to high voltage ...
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1answer
342 views

One-time fuse for disconnecting/breaking signal path

I am looking for an IC solution, ideally, but alternatively also could use a tiny circuit that would allow to accomplish the following feature: Trigger an event by MCU that will fuse-out/disconnect ...
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1answer
70 views

How to fuse batteries connected in parallel?

I have two GEL batteries 12V/130Ah and want to connect them together in parallel. Currently I have one battery in the system and it is fused on the positive wire before the isolation switch. I ...
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1answer
38 views

Integrated Circuit Epoxy Outer Molding [duplicate]

I'd like to know whether flame retardant epoxy resins, the FR-4 brominated type for instance, are used in the outer molding for integrated circuits or whether it's just a plain epoxy resin. ...
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0answers
129 views

ATX Power Supply trips with DC Motor

I am using an ATX switching power supply as a power source for my motors and air compressor. Specifications of the PSU is: Type: ATX 12V Model: 850UB Vac~ input: 230V, 5A, 50Hz Vdc MAX DC Output: ...
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0answers
92 views

Tp4056 overcharging

I have combined five 18650 cells in parallel and i am charging them using a single tp4056 circuit . The problem i am facing is that the module keeps on charging. I had to stop the charging manually at ...
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2answers
92 views

protection of industrial analog input modules for high-voltage signals

I'm looking at ways to design a multi-functional analog input that can take both voltage and current inputs for industrial applications. The voltage signals are in the 0-40V range and the current ...
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1answer
37 views

Do i need to protect a DC adapter from current spikes (produced by buck converter)?

I wonder if i need to protect my ac adapter, which has over-voltage, over-current and short-circuit protection. The ac adapter feeds a buck-converter which uses a low-side n-mosfet switch ...
1
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0answers
67 views

TVS protection burnt too easily

It's about an year that I'm using TVS diodes to suppress spikes from the AC motors (240V - max 240W) that drives my roller shutters and protect the solid state relay that actuate the motor. What is ...
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1answer
85 views

Bypassing DSLR battery to power camera from power supply cheaply with bidirectional optocouplers

I am trying to power my Nikon DSLR with a permanent power source instead of the battery for long captures (overnight) without buying the overpriced battery adapter. I can't simply connect a AC-DC ...
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3answers
90 views

Is it necessary to add fuse protection (at the inputs) when using multiple DC-DC converters?

I would like to know if it is necessary (or recommended) to add fuses at the inputs when using multiple DC-DC converters. I have attached a quick schematic to illustrate what the design would look ...
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1answer
73 views

Powering module directly from LiPo Charger with LiPo connected

I have a GSM module (Particle Electron) which has pins for powering it from a LiPo battery. The pins accept voltages from 3.6V to 4.4V. The module can also be powered from 5V supply through another ...
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2answers
57 views

Can an array of fuses protect a PC port from damage?

I'm paranoid right now because I made another circuit meant for the parallel port of the PC. While all my previous experiments involving the port were successful (except for one experiment I made a ...
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2answers
96 views

Protecting microcontroller output

I'm designing a very simple microcontroller breakout board. I wonder how can I protect microcontroller output pins against accidentally connecting another signal to one of them and burning the pin's ...
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1answer
105 views

Microwave oven with no heat, Bad design or wrong component choice? [closed]

Few days ago, my Magic Chef MCD990B microwave oven magically passed away randomly and so suddenly that I didn't even have time to say goodbye, not that I have used it heavily or considered it as my ...
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1answer
146 views

How do I protect an electronic circuit

I’m beginner in electronics and i have project for grow LED light and i want to connect LED with timer. My inquire how I protect my circuit. My circuit Adapter 12V 1.2A Timer (5-20v) up to 5A 2 * ...
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1answer
202 views

Multiple DC power source to the board protected by schottky diodes

Provided is the DC power supply block to the micro-controller development board from one of the leading MCU manufacturers. I need help to understand this arrangement. I will use two sources V5-...