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Questions tagged [fuses]

Questions regarding physical fuses. A fuse is 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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Does sealing low voltage high current fuse box from air exchange affect the current where the fuse blows?

I have a (Victron Energy) low voltage high current fuse box, which is intended for mega fuses such as 80A, 100A, 125A. Unfortunately, the fuse box has quite large holes where the thick cables go in, ...
juhist's user avatar
  • 1,752
0 votes
2 answers
84 views

Need to replace an SMD fuse marked "o". Image available

I can't find a replacement of this SMD fuse on the internet. I'm trying to fix my white screen monitor issue like in this video: https://m.youtube.com/watch?v=HxusdMp4Nko
Moltu's user avatar
  • 3
5 votes
7 answers
1k views

Does it matter if a fuse is on a positive or negative voltage?

I have a power supply with -5V DC output. Can I use a fuse 5V 0.5A for this -5V rail as if it was 5V 0.5A? The rail I want to put a fuse on goes into the motherboard. The motherboard does not have any ...
Anton Andreev's user avatar
4 votes
2 answers
169 views

Rated current vs melting integral of fuses

I am looking for a fuse for my project, and have become confused about how the current rating and melting integral (I2t) relates to each other. My understanding is that: The current rating indicates ...
mjuels's user avatar
  • 43
0 votes
2 answers
68 views

Can a low breaking capacity cause a fuse to blow?

A fuse in one of my speaker (SRT 212) broke due to what we think was a disfunctional power strip (after that, the speaker would not turn on anymore). The reference of the fuse written on the board ...
Lucas Charbonnier's user avatar
0 votes
0 answers
17 views

Thermal fuse replacement

I need to replace a failed thermal fuse, but I cannot match a replacement exactly. I need a ShengPing SPF70-73C, TH=45C, TM=115C/10a @ 250v. How close do I have to match these specs, over and/or ...
Gregory Bitterman's user avatar
3 votes
3 answers
551 views

What is 'T' rating on a glass fuse?

I have a 12VDC cuircuit board with a blown glass fuse (careless wrong polarity). The bands are brown, blue, red plus a wide blue band. Looking at the chart it says the time/current rating is T. Is ...
Vic's user avatar
  • 131
1 vote
1 answer
55 views

When to include a fuse in a battery protection circuit?

I am working with the MAX17320 and I am looking at two MAX17320 example circuits from AD - the MAX17320 Eval Board and the MAXREFDES1299 for inspiration. Each schematic is roughly the same, except the ...
user1045680's user avatar
2 votes
1 answer
56 views

Protecting a soldering hot plate with thermal fuse

I am DIYing a reflow soldering hot plate, with an SSR allowing to regulate the hot plate temperature. However, I understand that SSRs can sometimes fail closed, which basically means that this would ...
Jambon's user avatar
  • 41
0 votes
0 answers
39 views

Plugable Varistor and Fuse Cartridge for easy and safe replacement

As I have concluded with some tests, by reading some posts and even asking a question on this forum, Varistors can get damaged with multiple or even just one cycle of use. They fail as a short, being ...
Dinis's user avatar
  • 73
1 vote
4 answers
126 views

Risks of placing Varistor before Fuse for Mains Voltage

I have seen many questions on this and other forums asking about the best option to place the fuse relative to the varistor to protect it from mains voltage spikes and the answer was unanimous: The ...
Dinis's user avatar
  • 73
0 votes
2 answers
40 views

Fuses to protect a NFC 3-Phase Control Relay

I am trying to understand which fuses to use to protect an NFC 3-Phase Control Relay (RMNF22TB30). The installation guide describes that a 1A CC/gG fuse for each phase is needed. I would like to use ...
Gabriel's user avatar
  • 21
0 votes
2 answers
116 views

Why fuse the centre-tap in a single-ended full-wave bridge-rectifier PSU?

I am looking at an on-line schematic and struggling to understand the function of the fuse. The schematic is from https://turneraudio.com.au/leakampmods_files/schem-leaktl12-protect-2005.gif The ...
Fish's user avatar
  • 1
1 vote
1 answer
31 views

Power line configuration [closed]

For power, which configuration is best? Fuse first, followed by an ESD diode ESD diode first, and the fuse next
Pavan Kumar's user avatar
0 votes
2 answers
97 views

Not able to correlate the graph and table for the I2t rating in a fuse datasheet

In the datasheet, the I2t rating of a 5A fuse is 0.055 at 10 times In. Using the same value to estimate the trip time for the 10 A condition, I get 0.0022 seconds. In the graph below, it comes ...
Dynamic_equilibrium's user avatar
0 votes
0 answers
42 views

What do the following parameters indicate in a resettable fuse?

I am not sure how to decipher the Pd and R1max info in the below datasheet. Does PD indicate the tripped state power dissipation or maximum power dissipation under non-tripped operation? If you ...
Dynamic_equilibrium's user avatar
0 votes
1 answer
55 views

What is the criteria to choose between PTC thermistor and resettable fuse (PPTC)?

Wiki states: (PPTC) are similar in function to PTC thermistors in certain situations but operate on mechanical changes instead of charge carrier effects in semiconductors. Another wiki says there is ...
Dynamic_equilibrium's user avatar
0 votes
2 answers
101 views

Capacitor calculation

I am new to the concept of pyro-fuses, if the firing current is 1.2A/2ms, this means that I need to provide at least 1.2A for 2ms for the pyro to be triggered. Now if I want to use a capacitor to ...
404's user avatar
  • 15
0 votes
0 answers
55 views

Calculating/choosing the right capacitor

For designing a pyrofuse driver, I need to add a capacitor that serves as an alternative power source in case of main power supply cut-off. The driver has a configurable firing pulse of 1.2A/2ms or 1....
Bananabread's user avatar
0 votes
2 answers
160 views

How open this Christmas light plug to change fuse? [closed]

I'm trying to get to the fuse in this plug (pictured below) and it looks like I'm going to break it instead. All the videos and instructions I've found show a different plug that it is very easy to ...
Rodo's user avatar
  • 1,130
2 votes
0 answers
196 views

ESP32 with two power supplies (AC/DC + USB) using Schottky diodes

I'm building a small circuit to power an ESP32 with two different power supplies. Normally the circuit will be powered from AC, using a Mean Well IRM-02-5 AC-DC power supply to get 5VDC out of 220VAC. ...
Daniel P.'s user avatar
3 votes
6 answers
786 views

Is there a better way to protect my power supply other than the efuse?

I use fairly cheap standard power supplies with no protection in my circuit experiments, usually with output of 5V, 12V, 18V, 30V and a current up to 1A. I use standard glass fuses to protect these ...
Shamooooot's user avatar
0 votes
0 answers
52 views

Solar system: 40 A DC AND fuses. What is the difference between Audio and Solar version of this fuse?

So, I've purchased some 40A ANL fuses and holders for my solar controllers and I'm hooking them up tonight after the sun goes down. Due to a comment from a neighbor, I went back and reviewed my ...
boatcoder's user avatar
  • 437
1 vote
1 answer
674 views

Help identifying the fuse used inside a Parkside 20V lithium-ion power tool battery

I blew the fuse inside my Parkside power tool 20 V 4 Ah battery and was wanting to fix it. There is a guy just soldering the broken circular fuse. The image below is taken from this video at ...
user357116's user avatar
4 votes
2 answers
1k views

Why are PPTC based fuses not used in power sockets?

I live in the UK. The fuses that I have always seen are the glass fuses which look like this: When they blow they need to be replaced. They are present in all AC plugs. They could also be present in ...
quantum231's user avatar
0 votes
1 answer
89 views

Kicad telling me to connect pads together when I feel it's incorrect

Hey all I am wondering if this is the correct way to trace a fuse holder on my pcb. I would imagine that the top 2 pads connected to each other and the bottom 2 pads connected to each other. Running a ...
StealthRT's user avatar
  • 783
1 vote
2 answers
62 views

Fuse help F 4.0 A [closed]

I hoped to get help identifying a fuse in my underfloor heating wiring centre, the spec on the PCB is "F 4.0 A" but the actual fuse has written on it "T 2.5A H250V P". I think it's ...
Nick's user avatar
  • 13
0 votes
0 answers
47 views

Small Fuse for 600VDC with 6kA interrupt current

I'm looking for a 0.1A - 1A Fuse for a 600VDC system with an interrupt current rating of at least 6kA. I found some fuses like the TC-632414, which would fulfil the criteria, but they are quite big. ...
Felix Kunz's user avatar
0 votes
2 answers
284 views

What is the fuse with a label of T on it?

I'm working on a Playstation 5 and found that I needed to change this fuse. I'm not sure which this one is as there are so many types of tiny fuses out there. What does this T stand for? How should I ...
Patoshi パトシ's user avatar
0 votes
1 answer
41 views

Rating of circuit breaker for protection

This circuit breaker is rated as 12V-48V 100A and I have to use this circuit breaker between additional alternator (24V 100A) in my vehicle and additional battery bank to provide overcurrent/short ...
James Ross's user avatar
0 votes
1 answer
70 views

Fuses before or after vital components? [closed]

Why are fuses/circuit breakers usually placed right after the power supply and before any critical components? Fuses are designed to be the first thing that melts or breaks down when there's too much ...
Aden's user avatar
  • 27
0 votes
1 answer
162 views

How to predict the voltage drop due to a fuse?

My device runs from a USB supply, typical 5V, current typically 20mA, never beyond 100mA. I want to add a fuse. The JFC0402-0500FS claims rated current 0.50A (perfect for this application) and a ...
SRobertJames's user avatar
  • 1,119
1 vote
1 answer
73 views

Over-current/short-circuit protection for the battery bank

I am using a 24 V 100 A additional vehicle alternator for charging my additional battery bank of 24 V. I need an over-current/short-circuit protection for my battery bank. I am considering using a DC ...
James Ross's user avatar
1 vote
1 answer
86 views

How can I identify this SMD part with F200 marking?

Can anyone help me to identify this SMD part?
JohnnySmartCar's user avatar
11 votes
5 answers
4k views

Did a blown fuse in my multimeter damage my multimeter?

May be a little newbie question, but I since I am an electronics beginner and couldn’t find a direct answer I will ask it. I blew the 600 mA fuse on my brand new multimeter, I think I didn’t change ...
Hoekplaat's user avatar
  • 113
4 votes
5 answers
4k views

Fuse at 250 volts versus fuse at 12 volts

I'm getting mixed answers. Will a 250 volts, 140 amperes fuse blow as fast as with 12 volts?
JustaMe's user avatar
  • 57
2 votes
1 answer
121 views

Determining values when designing with thermal fuses; calculating influence of location/proximity to heat source & properties of protective coverings

The root question: Are there any best practice rules or guidelines for spec'ing out a system with a non-resettable thermal fuse? What criteria is used to determine what rating fuse is needed? I'm ...
JCReardon's user avatar
0 votes
1 answer
85 views

I purchased a box of car fuses ranging from 5 to 40 amps from EBAY. I want to test the fuse rating using dummy loads [closed]

I purchased a box of car fuses from EBAY. When testing the current draw on a new tire inflation pump, rated at 40 amps. I tested it using a 30 amp eBay fuse. The fuse started smoking, the fuse's ...
Philip H's user avatar
0 votes
0 answers
202 views

Should the DC-DC and solar charging go through the main fuse or dedicated fuse?

I am planning a 12V dual battery setup to be used in a car. The aux battery is a LiFePo4 battery and it will be charged via a combined DC-DC and solar charger (50A, fuse 65A). I want to add a fuse and ...
Alex's user avatar
  • 1
0 votes
1 answer
1k views

Looking for an SMD fuse spare part marked with "PP"

I am bit out of ideas for this SMD fuse marked with "PP", where I can only find "P" ones. It's about 2x1mm in size. Does anyone have a clue what that is? Maybe its no fuse, after ...
flohack's user avatar
  • 103
13 votes
2 answers
2k views

Can a small glass cylinder with "6.00" marking be a fuse?

My guess is that this part soldered to an SMD board is about 20 years old (it's from the controller of a Mecablitz 50MZ-5 wand flash). The controller currently is not working but that may be due to ...
user107063's user avatar
  • 3,763
0 votes
2 answers
131 views

How to use blade fuse in DC circuit as protection?

While trying to add a protection to my buck converter circuit I came across Blade Fuses, which are faster at breaking compared to glass cartridge from what I saw. The question is, how is such a fuse ...
Mito's user avatar
  • 411
1 vote
1 answer
82 views

Trying to locate a (resettable?) fuse that I believe may have blown entirely [closed]

I am led to believe that there is at least one (potentially resettable) fuse on this Bosch manufactured BMW PDC module. I am also led to believe it has a limit to the number of times it can blow and ...
StrattonL's user avatar
  • 115
0 votes
2 answers
143 views

Audio amp board keep blowing fuses

I have a electronic piano that stopped working. After opening I case I found that one fuse on the amplifier PCB had blown. I replaced the fuses but they immediately blew again. I have investigated the ...
Diziet Asahi's user avatar
0 votes
1 answer
80 views

Which value of fuse should I use?

So this 12 VDC LED rated at 1.5 watts i.e. 125 mA, The LED is run by a computer circuit which sends 12 V power to LED for on and off, exactly like a car turn signal blinker. Which value fast blow ...
administr4tor's user avatar
0 votes
2 answers
99 views

Restrict current from a 9 V battery to avoid blowing a fuse

I have an old landline telephone with a 250 V, 250 mA fuse. It will not be connected to a landline, rather, I would like to power it using a 9 V battery (for use as a musical device. I do this with ...
Yae's user avatar
  • 1
0 votes
0 answers
47 views

SMD PTC Fuse for 24 VDC

I am designing a new version of a PCB board with a microcontroller to drive two 24 V DC brushed motors, and I am looking for a self-resetting PTC SMD fuse for a 24 VDC supply line and max 2.5 A. The ...
Alinik's user avatar
  • 179
0 votes
1 answer
93 views

What is the point of triple JCASE automotive fuses?

Some JCASE automotive fuses come three in one enclosure. What problem do they solve? What do they do that three individual fuses couldn't do? {My pictures} The BUSSMANN MPF spec sheet (PDF) says; &...
Davide Andrea's user avatar
0 votes
1 answer
760 views

Do letters matter on thermal fuses?

DIY oven repair question. I need to replace this thermal fuse: Does it matter what letters there are shown i.e. YCW.dz YCWRY, <...
T.Todua's user avatar
  • 101
1 vote
0 answers
136 views

Why does the voltage over a fuse increase even though there is no current

I noticed during several fuse tests that when the current goes to zero (it might be that the fuse was melted down) the voltage drop over the fuse rises a certain period of time and drops down steep. ...
sokraton54's user avatar

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