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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.

4
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2answers
70 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 ...
0
votes
1answer
28 views

Use of internal PCB ground plane as ESD baseplate/EMC reference plane of product in plastic enclosure

I am designing an electronic product which will be housed in a plastic (non-conductive) enclosure. There are a number of, mostly shielded, I/O cables (Copper 10/100/1000Mb/s Ethernet, USB 2.0, RS232, ...
0
votes
2answers
73 views

RS485 line protection diodes

Can anyone confirm the correctness of D27, D28 diode polarities or should they be in opposite direction? Please suggest an which diode is suitable for this purpose OR is it better to use a zener diode ...
0
votes
2answers
42 views

Selection of External Current Transformer

simulate this circuit – Schematic created using CircuitLab I am designing a product for motor protection circuit. where I want to use customized external CT for application which gives me ...
0
votes
1answer
48 views

How can I simplify my design for a Surge Protection Device (SPD)?

I have found a basic design for a SPD and I would like to simplify it. However, I have little experience designing SPD circuits. This is my parallel type SPD circuit with embeded LED indicator: In ...
0
votes
2answers
105 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 = ...
0
votes
0answers
26 views

DMX protection circuit (diode clipper)

TL;DR I’m building a board that bridges the common types of DMX connector (various forms of XLR, RJ45, tails and product-specific terminals). There is a possibility that someone could accidentally ...
0
votes
2answers
56 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 ...
0
votes
0answers
36 views

US/Can - Maximum current in a single circuit in a 100A panel

I hope this is the right sub... I have a 100A pony-panel in the garage. I'd like to have someone add a wall plug for EV charging, ideally a 14-50, but I'd settle for a 14-30 if need be. I seem to ...
0
votes
2answers
93 views

shorting behavior of isolation transformer

I have a very expensive 500va 1:1 toroid transformer with to isolate workbench from ground. But I'm afraid to use it for fear the winding may burn up when something shorted. I'd like to know what is ...
2
votes
1answer
39 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 (...
1
vote
1answer
80 views

Rs-485 isolation

Hi, I have RS485 communication circuit as shown in figure. But it has no isolation, only SM712 is used for ESD protection. Now, i think it will be better to isolate the it.So, how can i isolate it? ...
6
votes
3answers
811 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-...
0
votes
0answers
30 views

chances of A4988 motor driver creating back current through the STEP and DIR pins

I am trying to drive 2 stepper motors using A4988 motordrivers and I am using the following circuit diagram as shown in the image Only change from the above circuit diagram is that I have not ...
0
votes
1answer
49 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 ...
1
vote
1answer
60 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 ...
1
vote
2answers
145 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 ...
0
votes
1answer
33 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 ...
0
votes
1answer
41 views

TPS26601 Industrial eFUSE Circuit Design

I have been designing a circuit for various Power protections like overcurrent, overvoltage, ...
0
votes
1answer
35 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 ...
1
vote
3answers
64 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 ...
0
votes
1answer
60 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 ...
0
votes
3answers
216 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 ...
0
votes
2answers
38 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 ...
1
vote
1answer
43 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 ...
0
votes
1answer
69 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 ...
2
votes
0answers
44 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 ...
1
vote
2answers
64 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 ...
0
votes
1answer
61 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 ...
0
votes
1answer
57 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 ...
2
votes
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 ...
0
votes
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 ...
0
votes
3answers
291 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 (...
1
vote
1answer
90 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 ...
0
votes
0answers
40 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, ...
1
vote
1answer
107 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 ...
-3
votes
2answers
100 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?
1
vote
2answers
132 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 ...
1
vote
1answer
73 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 ...
0
votes
1answer
124 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 ...
1
vote
1answer
80 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
vote
1answer
120 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 ...
0
votes
1answer
40 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 ...
-1
votes
1answer
164 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 ...
1
vote
0answers
64 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 ...
0
votes
1answer
55 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
votes
0answers
70 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 ...
0
votes
3answers
111 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 ...
0
votes
1answer
604 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 ...
0
votes
1answer
123 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 ...