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 ...

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8
votes
1answer
2k views

'Voltage Fuse' or better

I have a power supply with multiple outputs (5v, 12, 24v) According to the manufacture (and after testing) there must be a minimum load on the PSU for it to supply the stated voltages. Without a ...
18
votes
5answers
37k views

Fuses: What are the practical differences between Ceramic and Glass cartridge fuses

What are the practical differences between ceramic and glass tube cartridge fuses? I am trying to find new fuses for a piece of consumer electronics. The original fuses are going out of production. ...
4
votes
5answers
749 views

Why do 0.02A fuses not protect a person? Why no protection from shocks?

I understand the user here so that fuses do not protect people from shocks. I am planning to put put fuses such as fast-blown fuses and PPTC fuses around all kind of positions such as ...
3
votes
2answers
622 views

Designing with fuses…when to use?

Most circuits that I have designed in the past deal with low voltages...sensors, communicating with other chips, etc. When would I need to consider the addition of fuses into my designs? Sometimes I ...
6
votes
2answers
1k views

Short circuit protection for high current wearable: fuse, polyswitch, TBU, circuit breaker, something else?

I am thinking about design elements for a rather high current, battery powered, wearable application. Maximum current of 40A at 5V, but typically around a third to a half of that. Power would come ...
27
votes
3answers
3k views

Why did my fuse not blow?

I purchased a few fuses to get familiar with their workings, and I was surprised to see that the 100mA fast-blowing fuses I bought happily conducted up to 215mA (6V power supply, 10\$\Omega\$ ...
21
votes
5answers
22k views

What not to do with a Multimeter

So I just bought and installed a new fuse for an analog multimeter I scored for free and now it works like a charm. The new fuse is the same rating as the blown one I found inside, which is 0.5A ...
5
votes
3answers
4k views

When should you use a fuse?

When is it actually practical to use a fuse? Like lets say your building a robot using an Arduino.....what area would you want to protect the most with a fuse? I mean do they even make fuses that ...
1
vote
4answers
134 views

Benchtop circuit breaker

I repair electric appliances and tools. Every once in a while, the main circuit breaker trips when I plug in a device. I don't want to prevent a circuit breaker from doing its job, but I would prefer ...
8
votes
4answers
4k views

Can a fuse be placed after a load?

Considering that the regular treatment of a fuse is to place it on the positive side, "before" a load, is this just common practice, or is it backed by an actual reason? Can a fuse be placed on the ...
8
votes
6answers
29k views

How does a fuse blow at its current rating, regardless of voltage?

I know from reading elsewhere that it's safe to use a fuse with a higher voltage rating when replacing one, so long as the current rating and reaction speed is the same. For example, if a fuse is ...
7
votes
4answers
1k views

Why aren't high-current ammeters protected with a fuse

Why is it that the low-current range on an ammeter (200mA) is fused and not the 20A range? I recently lost a multimeter because I connected the ammeter in parallel with a power source by mistake. ...
3
votes
2answers
3k views

Why do PTC fuses have different voltage ratings depending on package size / hold current?

I've been trying to figure out the PTC fuse I want to use in a little automotive power supply circuit and I'm a little disconcerted by the max Vdc ratings most of these things have. For instance, ...
3
votes
4answers
2k views

Need help debugging my project: Fuses popping like crazy, but I can't find the reason why

I recently made a voltage and current controlled supply from a kit I found. It worked for about 15 minutes and then fuses started popping. Unfortunately, I have no idea why, because power supply ...
2
votes
2answers
2k views

Should a fuse with the correct amps, but is physically too small, still power my stereo unit?

I'm not sure if I'm asking the right kind of question for this site. But if someone could help me, I'd be grateful: I blew a 125V 2.5A fuse in my home stereo head unit. I couldn't find that fuse at ...
2
votes
1answer
4k views

How do I choose the right replacement fuse for my multimeter?

I have a BK Precision 2709B Multimeter. I managed to blow the uA fuse (500mA/500V fast blow ceramic) on it. Is it an ok to replace this fuse with a 500mA/1kV fast blow ceramic fuse? What impact would ...
1
vote
3answers
333 views

Where/How should I fuse this transformer?

Background: I have a step-down transformer P241-5-36, which is a single mains primary coil to 36V Center Tapped (18-0-18) secondary. I would like to use this transformer to build a linear regulated ...
0
votes
1answer
62 views

Glass fuse identification - Siran No. F 13 4A

We have a glass fuse for a 12v lighting circuit that has "Siran No. F 13 4A" written on paper inside it. The circuit takes 5.5A at the moment with all the lights switched on without the fuse blowing. ...
0
votes
2answers
225 views

PCB design for automotive fusebox?

I am currently in the process of designing an automotive (motorsport related) fuse-box as a side project to my studies. I've not had much luck searching for fuse holders (20 position) however while ...
0
votes
1answer
727 views

Choosing Fuses or MCB in 24VDC vehicle circuit

I am currently designing a 24VDC circuit for a small vehicle. I personally prefer using MCB's since they are simple to reset and easy to detect faults in the system, although i do find it rather hard ...