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Questions tagged [fuses]

Questions regarding physical fuses. Fuses are a safety device consisting of a strip of wire that melts and breaks an electric circuit if the current exceeds a safe level. PPTC, PTC, and Polyfuse questions should use the Polyfuse Tag. Please keep in mind that repair questions are typically closed if not within the scope of the Site and FAQ.

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1answer
31 views

What is the difference between F5AL250V and F5L250V fuses?

In the glass fuses' code F is for fast blown the second number is the current, but I ignore what is the difference between L an AL (if there is any). Could someone explain this.
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48 views

Selecting suitable High Voltage / High Switching NPN transistor replacement for old PSU

I have an old Olivetti PC where the main input fuse in the PSU blows as soon as I flip the power switch (the same instant). Due to the specific form factor of this PSU I am thinking about trying to ...
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1answer
50 views

Fuses in Series for High Voltage Where Maximum Current is Low

I'll start off by saying that I know this not a recommend practice. I'm looking to build a regulated power supply that can supply 1200VDC at 300mA. The supply consists of a transformer, xenon tube ...
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0answers
86 views

Why use an inductor as a fuse?

I opened a small "wall-wart" power supply that had failed, and discovered the culprit to be a low-value (100µH) standard (axial, green) inductor. This inductor had a visible crack along it, as if it ...
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1answer
49 views

800 A 12 V bank Winston LiPo4 fuse size?

Installing this bank, with about 1 meter to my inverter/charger, but I want to add a fuse on the positive side. The inverter is a Victron 3kW. The charger is 120 A. The cables that I have now are ...
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1answer
47 views

Troubleshooting Power Supply Fault

I was using my 12 V Power Supply, and suddenly a spark occured near the AC input terminals. The power supply stopped functioning. I opened up the casing and found some blackish colour near the 250V 3A ...
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1answer
92 views

Would the diode and the fuse protect the other components if power wiring is reversed?

Would the diode and the fuse protect the other components if power wiring is reversed? Is the polarity of the diode correct?
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1answer
59 views

Can I replace a 6.3A fuse with an 8A fuse [closed]

I'm shopping for a Universal Travel Adapter and I've found this one which seems to meet all my requirements. I've used a nice one for years and it recently blew out and it doesn't have a replaceable ...
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1answer
60 views

Popped a power supply fuse - What did I do wrong?

I recently purchased a 5V 40A power supply that looks similar to this: It didn't come with a power cable, so I found one that I wasn't using and stripped the side opposite the three-pronged side (the ...
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1answer
54 views

Zener diode in parallel with both the input terminals and the output terminals

"There is a zener diode in parallel with both the input terminals and the output terminals. Combined with the fuse these should help in reverse polarity situations (it should blow the fuse before ...
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1answer
43 views

Why did my Atmega328p chips stop working?

I am fairly new to embedded programming. I bought some Atmega328P U chips (not Atmega328P-PU). I have two Arduino boards and the chips worked just fine, and were letting me upload sketches. One of ...
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3answers
70 views

Can I replace a 12a fuse with a 15a fuse on a 12v - 120v automobile inverter?

I'm hard wiring an inverter into my automobile. Tapping into a 15a fuse in the fuse box. To hard wire it I had to remove the "cigarette plug" and in so doing removed a 12a fuse. I have an inline fuse ...
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0answers
54 views

PTC or One time Fuse or fusible resistor for li-ion protection.any suggestion?

I designing a kind of portable device ,it contains 450mAh Li_ion or Li_Poly Battery (depends on space on PCB). I design this system for mass production (10k-20K). I want to add overcurrent protection ...
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2answers
4k views

What type of glass fuse is this and what does the spring do?

This is a standard sized glass fuse like what cars used before the 80s. I can faintly make out 20A, but I’m not sure what to call it in order to find a replacement. The fuse in the picture has not ...
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1answer
49 views

Poly fusing external peripheral device

The design I am working on is having peripheral connector with +5V power in it providing the voltage to the would-be connected device. There's relatively a long way inside the design from the ATX ...
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1answer
56 views

Pin protection fuses

A colleague of mine created the following circuit with the 3x 5A fuses for protecting the power connector pins from oxidizing and melting the connector plastic (we had some cases, when the connector ...
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0answers
62 views

Using thermal fuses in parallel?

If one has some 216C 10A thermal fuses, could one wire two in parallel in order to fuse a 10A heated bed on a 3d printer? The bed is 110V and 1100W btw, so in normal operation it should draw 10A. ...
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1answer
45 views

Can I use a simple fuse to protect a CMOS over current?

I'm designing an output with a MOSFET transistor to control loads such as relays, motors or incandescent lamps, similar to the outputs of a PLC. Obviously, there is no problem as long as the load ...
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2answers
31 views

Should I look at nominal or max battery voltage for choosing resetable fuse?

I am building a LED/Camera control circuit that is going to be using a 14.8V Li-Ion battery as a supply. I want to put a resettable fuse to prevent short circuits from blowing up too much since this ...
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2answers
119 views

Using diodes for reverse polarity protection

I want to protect my circuit against reverse polarity, by simply adding two diodes in parallel between the + and - input cables. So if the polarity is reversed, the current will go through those ...
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0answers
16 views

Replacing thermal cutoff / fuse, what temperature to match to

I'm replacing a thermal fuse that has gone bad (already verified that the temperature of the device monitored was not going too high) and was wondering how / what to match the temperature printed on ...
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1answer
46 views

Trying to source a PCB component (a slow blow fuse I believe!)

I’ve stumbled upon this forum in a search for a replacement part for a PCB that makes up a digital ballast for a HPS light used in basil clone production. I’m handay with a soldering iron but I am ...
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1answer
168 views

Can I use a transistor like a fuse?

I just started learning about transistors, so I was wondering if I could build a circuit where short circuiting across the load caused a transistor to cut off power (like a fuse). My idea was that ...
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0answers
32 views

Suggestions on simulating fuse characteristics electronically?

Assume that we have an isolation transformer 230V in 230V out and that we measure the output current with a current transformer with known transfer function. We compare the current to a settable value ...
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1answer
62 views

Safety switch “breaking capacity” vs. voltage

In the context of safety switch rating (fuses, circuit breakers, etc.), the concept of breaking capacity refers to the maximum electric current which can be safely interrupted by a tripping safety ...
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2answers
67 views

Can i use 1 fuse for all the outputs to protect my power source from overcurrent?

Can i use 1 fuse for all the outputs to protect my power source from overcurrent by connecting the fuse to the ground wire? I have 3 outputs: 3.3V, 5V, 12V and i want to protect my power source when ...
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1answer
73 views

Does a 5A Car Fuse Blows in a 12 Miliseconds Peak of 6A, in a 220v Circuit?

Thinking here in using a 5A fuse in a certain circuit, but it may reach 6A sometimes for a mather of 10 or 12 miliseconds only. That way, would this fuse blow or it would sustain and blow only in ...
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1answer
94 views

20A or 30A fuse in 200A fuse clips — is nesting reducers OK?

So, I am trying to figure out the cleanest way to make a 20A or 30A tap from a 200A circuit (single hot + neutral) that is being run through a fusible safety switch (NEMA style, as this is in the USA),...
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1answer
59 views

Need to substitute a fusible resistor in an inrush limiter in a PSU

HP 6023A PSU again :) This time R1, which is a 20ohm 7W fusible. The relay pulls 1s after power is applied and I assume that the general idea is to take the egde of the rather substantial inrush into ...
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1answer
49 views

How to chose resettable fuse for 24 V DC to 5V DC converter?

I want to use a 24V to 5V DC converter, the PYBJ10-Q24-S5 (https://www.mouser.fr/datasheet/2/670/pybj10-om-1548233.pdf). Page 7 of the datasheet, they specified the EMC Recommended Circuit which ...
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1answer
94 views

Can I use a 24V, 1A fuse for a 5V application?

I have a 5V power supply which needs protection. I only have a 24V, 1A fuse. Can I use this fuse for the 5V power supply. As Watt = R * I * I = V * I. As rated W is constant for a given fuse, will ...
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1answer
43 views

How to choose the correct fuse in a double paralled battery supply system?

Suppose I have the following system: simulate this circuit – Schematic created using CircuitLab As you can see we have: Two 500V battery with an estimated 500mohm average internal resistance. ...
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1answer
61 views

Fast-blow instead of slow-blow fuse in consumer hifi power supply

I have a power supply unit for a hifi pre-amp. The power supply takes a slow-blow fuse (T2.5A/250V). If I use a fast fuse (F2.5A/250V) instead, how likely is the fuse to blow during normal power-on?
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0answers
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Problem calculating fuses

I am calculating a fuse and I'm having a bit of trouble. I have a 12v 2A power supply that I want to protect, so my first thought was to place a fast 250v 2.5A fuse in series so it should blow if a ...
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2answers
140 views

Why a double fuse is used in some applications?

In some DC applications in an isolated system (i.e. no grounding), sometimes two fuses are used: one is positioned on the positive (Vcc) line while the other is located on the negative (return path or ...
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1answer
48 views

Is it safe to go over a fuse holder voltage rating?

I am looking to buy a few online fuses and fuse holders for the mains power into a kiln I’m fixing up that runs on 240V and draws 45A. A thick 6 AWG wire connects to mains power, then is split into ...
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2answers
133 views

What is the advantage of putting capacitors in parallel with glass fuse tube

I have seen a board and I wonder to know what would be the advantage of having capacitor in parallel with fuse.
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1answer
84 views

How are OTP fuses in ICs implemented?

One-time programmable (OTP) fuses are common in ICs. How are they typically implemented, on the silicon level? I know that they generally work like larger fuses, i.e. they can be blown but not ...
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8answers
3k views

Why do fuses burn at a specific current?

We usually specify the maximum current that a conductor (such as a fuse) can handle without burning. But doesn't the conductor really fail when a certain amount of energy/heat has been dissipated in ...
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2answers
37 views

Can I use a 32x6mm catridge fuse with a fuse holder specified at 38x10mm

This is my first time incorporating fuses in my project. I am trying to source for some DIN rail mount fuse holders and the accompanying cartridge fuses. After much searching, I have found the fuse I ...
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0answers
47 views

Protection Devices in DC ciruits

I am putting together a design for a custom Electrical panel. The panel consists of mainly DC powered components (Sensors, Controllers). Components are to be mechanically positioned using a DIN rail. ...
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4answers
74 views

Fuse Identification

Would anyone be able to help me identify this fuse? The markings on it are: "51NM 250V 1.6A". It is a glass 5x20MM fuse, I am just wondering if it is a fast or slow blow fuse so I can order a ...
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5answers
283 views

Circuit to detect broken fuse

Consider the following circuit: [edited schematic] DC_gen1 and DC_gen2 are two +28V dc ideal generators. ...
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1answer
112 views

Placement of varistor with respect to fuse

My design includes a pretty standard AC/DC converter powered by mains for intended use at home. For overvoltage and overcurrent protection, I am planning to use a combination of varistor and fuse ...
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2answers
83 views

What voltage will blow a fuse with given load resistance?

What is the maximum voltage that a circuit with a 20ohm load and 2.5amp fuse can be connected so that the fuse does not blow? Can someone answer this with an explanation please?
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0answers
65 views

RCA VCR Fuse Question [duplicate]

I have an old RCA VCR (model number VR501) which contains a fuse in the power supply I am repairing. From the markings on the fuse I can only tell that it is a 1.6A 250VAC glass 5x20mm fuse, however I ...
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2answers
44 views

Old stereo with a blown fuse [closed]

I have an elderly but much loved Kenwood cd/radio/tape stack that has blown a fuse. The fuse rating is T800mAL 250volt. For reasons beyond me these don't seem to be available in the UK and the Amazon ...
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1answer
99 views

Identification: Is this an 150A fuse? Or something else?

Can anyone else identify this element? What is it? Seems to have 150A stamped on the left side - is it a fuse?
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1answer
144 views

Help Identifying Inverted Fuse Symbol

The following diagram shows fuses off each of the PT connections (standard IEC fuse symbol) but it also shows a fuse symbol with inverted colouring on the neutral connection. This second fuse also ...
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3answers
337 views

Is this fuse time-current curve wrong?

I'm looking at the datasheet for the Bel 0ADKC /0ADKP fuses. In it is this: These curves don't seem correct. Notice that the curves for fuses with >= 800mA asymptotically approaches a value that ...