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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Is is safe to deal with wiring after only shutting off the room's fuse, but not the main switch? [migrated]

I think the question title says it all: Given a distribution board in the house (220 VAC), is it enough to shut off only the room's fuses, or must one shut off the main switch for the board before ...
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2answers
55 views

DC Motor drawing too many Amps

I have a treadmill incline motor that is blowing its circuits fuse every time it starts to run. This is the motor that lifts the treadmill up and down. The motor is labeled: Output: 65W Input 36VDC ...
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2answers
195 views

Did I choose the correct fuse for my USB powered circuit?

I need to drive a circuit (operational current 150mA) with a USB port. I would like to protect the port with a fuse and from this question I concluded, that what I want is a PTC fuse. Is that the ...
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1answer
18 views

avrdude: initialization failed, rc=-1

when trying to program the fuses I get this known error message: $ sudo avrdude -c usbtiny -p m328p -U hfuse:w:0x05:m avrdude: initialization failed, rc=-1 ...
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3answers
109 views

What is the function of fuse here

The datasheet states that TPS2400 protects the load from an over-voltage, by disconnecting the load from the power supply (Q1 goes off), without blowing the fuse. Why is the fuse F2 here, if there ...
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3answers
61 views

Short Circuit Indicator circuit

This circuit was designed to save electronic components in the assembled board from damage. It gives warning beep if there is a short circuit in the assembled board. Thus it helps to switch off the ...
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4answers
138 views

Turning on a led with negative voltage

I have been using this fuse blown indicator circuit for a bit, it basically works perfectly fine with positive voltages no matter if there is or nor a load connected The problem starts when I feed ...
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1answer
34 views

Can't read/write to/from the atmega328p

I cant communicate with the Atmega328p. I've flashed fuses low: 0x59, high: 0xD9 and changed wiring. Now I've connected 16Mhz crystal to the XTAL1, XTAL2 pins, and 2x22pF to the crystal. But I can't ...
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2answers
102 views

How can I work out if a cable can take a momentary current spike?

In this video here, almost 1000A is being run through a 10mm steel bar, and after a minute or so, it melts. https://www.youtube.com/watch?v=YzZ3aJqmT-M So in terms of charge, 60,000C applied for 1 ...
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3answers
104 views

Is this the proper way to fuse a DC/DC Converter?

I am designing a solar power system for camping. I'll use a couple different DC/DC converters to provide DC voltages for the specific items I want to power. I want to properly fuse the various ...
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1answer
53 views

Can i replace a 0.75A 76V SMD fuse with a 1.25A 250V one? [closed]

It's for an LCD TV inverter. The seller said I could even use a thin wire. I'm not sure about that that's why I still bought it but I want to make sure before putting it in. It seems that it's for ...
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1answer
68 views

4 iPad Air charging circuit indicator led not working

I developed this circuit in order for it to be connected to 4 ipads at the same time the current they use to charge when they are on low battery goes around 1.8Amps, That its working as intended, ...
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2answers
54 views

Bitbang ATMega-328PU with CT210x using avrdude

I have made a breadboard-arduino with an ATMega-328PU and the standard components taking help from http://arduino.cc/en/Main/Standalone I interfaced the CT2102 Breakout Board with this assembly: DTR ...
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2answers
504 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 ...
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0answers
86 views

Can I determine a formula for fuse disconnection times?

This is the first time I have used this stack site so am not 100% sure this question is on topic (based on the tags I couldn't find) but thought someone may still be able to help me. For those not ...
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4answers
236 views

Why does a 10A fuse blow at 10A and 5V or 10A and 500V?

Something that's always puzzled me: Wire and fuses can handle a given max current, pretty much regardless of voltage. A 10A fuse will blow if you exceed 10A, if the voltage is 5V or 500V. Why is ...
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1answer
76 views

Battery power in the home: Fire Safety

I would like to use 12v LED tape powered by an 8 x AA battery holder and switched with a motion sensor. This will be connected in my home 24/7, so I would like to know what precautions (if any) I ...
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2answers
195 views

Turn on an LED when power is lost with a relay

A friend of mine has just finished his race car but is having fan issues. What I want to help him do is setup an LED that turns on when the fans have lost power. Often the fuse blows. I would assume ...
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0answers
184 views

Atmega32 can't verify after setting correct fuses for external crystal. HELP

I am having trouble with some Atmega32A's purchased off from eBay. The MCU's does not seem to be fake as they are functioning properly. I am experiencig the following problem: I want to use external ...
2
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1answer
120 views

AC Short-circuit Protection

I have a bunch of electro-mechanical relays on a board intended to switch 220VAC for CFLs. The maximum load on the relays will be 100W with inrush currents of upto 2A (lasting for less than a second). ...
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3answers
118 views

What are the big plugs for that you find on high demand devices in North America (120V-Areas)?

Talking about AMEA socket system and 120V. High power demand devices like A/Cs do have bigger plugs with some switches on them. What exactly is their purpose? Seems like a fuse but isn't the socket ...
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1answer
95 views

Does any thermal fuse with the same cut off temperature work?

Would any thermal fuse cutoff for 216°C work as a replacement for the fuse in the picture below?
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4answers
233 views

Is it reasonable to use a current limiting diode in place of a fuse?

I'm trying to source some fast-blow 5mA or 10mA fuses but Littelfuse has discontinued the only reasonably affordable ones I have found. My circuit when operating properly will not output more than ...
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1answer
102 views

1:1 isolation transformer fuse on secondary side - an option?

We sometimes use an old self build 1:1 isolation transformer (150VA) in our company to isolate devices under test. It is equipped with a primary 500mA fuse (slow) in series with a on/off switch. ...
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3answers
127 views

preventing blown fuses in simple circuit

I am trying to prevent blowing fuses in a simple circuit: that consists of a battery(12V), fuse, and 2 lights(50W). There are no switches; the lights are connected and disconnected from the live ...
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1answer
49 views

Downsides of using 5mm fuses in 6.3mm sockets

For my multimeter I need to replace a fuse. It is 6.3mm in diameter, 25mm long, rated 500mA/250V AC and 1500A interrupt rating. I have a couple of such fuses, but they are 5mm in diameter, and ...
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1answer
94 views

Use a relay as a resettable fuse?

I was thinking; If a relay is used to power a circuit AND itself, if the circuit is shorted - the relay should lose its own power and turn off - almost like a resettable fuse. To power it up, I would ...
25
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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\$ ...
5
votes
3answers
162 views

Given metal dimensions and material, is it possible to determine the maximum current that the structure can handle? [semiconductor processing]

I have a linewidth structure that has very low resistance. I want to know the maximum current that this structure can handle. Since the resistance of the metal is so low, it's hard to measure the ...
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3answers
259 views

AVRDUDE with buring settings of AVR Studio

I make my own electronic boards often with an Atmel ATmega328P. I used AVR Studio for programming. Now I tried to make the same settings with avrdude and it looks, that they are not really ...
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3answers
151 views

What do the abbreviations “SPF” and “SPH” mean with respect to fuses? (Single line drawing for 480 V system.)

There are two lines connected between the transformer low voltage side and the 480 V bus, one with a fuse labeled "SPF" that connects to a GE power quality meter, another with a fuse labeled "SPH" ...
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1answer
94 views

How can I protect against shorts in low voltage AC ~16V

I'm looking for a method of protecting a circuit against shorting. I would rather not use a regular fuse as I expect I will short the circuit (unintentionally) fairly often (probably once or twice ...
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1answer
56 views

Rating for this circuit breaker at 120 voltsAC

Here is a circuit breaker rated 2 amps at 32 volts DC and 2 amps at 250 volts AC What is the amperage it will break at when I apply 120 volts AC
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1answer
300 views

What are the dangers of a DIY fuse in a multimeter?

For the past few years I have been running my Fluke 79III without a fuse in it's F44.100A 1kV fuse holder. This has meant that I've been unable to use the 40mA circuit. When I blew the old fuse, I ...
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1answer
2k views

Fuse configuration AVR dude for external 12MHZ crystal in Atmega 168

I have 2 microcontrollers (Atmega 168PA-PU). So far I have run the following program in one of them (say mc1). Now when I run the same code in the other one it gives erroneous results. Someone ...
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1answer
108 views

Can I use a 600VAC PTC resettable fuse in a 700VDC application?

I've inherited an old design, and a part used has gone out of production. This part is a PTC resettable fuse, used in a bootstrap circuit, so it's one-shot. When the PTC opens, it has ~700VDC across ...
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3answers
137 views

How do I size fuses to handle sudden changes in AC line voltage into a capacitive load?

Suppose I have a rectifier on the AC line, followed by some caps and a load. simulate this circuit – Schematic created using CircuitLab If the AC line is suddenly increased, there's a ...
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3answers
379 views

Why is this switched power inlet fused on both load and neutral sides?

I've purchased a Schurter 4304.6090 power inlet for a project and am a bit confused by the fuse configuration. The inlet requires two fuses: one on the load side and another on the neutral side of the ...
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1answer
309 views

How to identify value of a surface mounted fuse

I have a PCB from a WIFI router and there is a lot of little surface mount components. I am looking for fuses, some of them might actually be them. My question is how do I identyfy them and find out ...
5
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3answers
536 views

Why isn't ammeter protected with a fuse

Why is it that the ammeter with low current (200mA) limit are fused and not the 20A one? I recently lost a multimeter because i connected the ammeter in parallel by mistake. Edit: All the ammeters i ...
4
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1answer
386 views

How do I know whether a fuse is a DC fuse or an AC fuse?

For example, I want to buy a 10A 50V DC fuse and a 10A 220V AC fuse online. Which website(s) should I go ? I tried on Mcmaster, but I could not get clear enough information of whether the fuse is an ...
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1answer
204 views

How do I calculate the voltage of a resistor after the fuse has been blown?

For example, theres a battery of 12v in a seris with R1 (resitor 1) of 49kilo ohms, then there's a blown fuse of 90uA, next is R2 of 11kilo ohms, then there's R3 of 60 kilo ohms. How do i calculate ...
3
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3answers
982 views

Transformer blows fuse at no load

I'm building a multi channel power amp and I am having trouble with the power supply. I'm in Europe, so I've got 230V mains and I'm running into a transformer which brings it down to 60V. The ...
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1answer
226 views

dual stage charger, is fuse needed?

I have a basic circuit: battery, fuse off (+)lead, 4 lights in parallel. My question is, when charging is a fuse needed? Also in the battery/charger circuit, which side is considered positive? ...
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4answers
786 views

Can I use a 500mA fuse instead of a 315mA fuse?

I have a guitar amp with a fuse on the power socket. It is a 250v 315mA slow blow fuse. My local electronic store only has a 500mA fuse. Can I use that or should I order a 315mA online?
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3answers
1k 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 ...
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3answers
266 views

DC Fuse Placement?

Imagine the following world's simplest diagram: 12V Battery -> 5V/3A Voltage Regulator -> Load My question is, would a 3A fuse best protect the circuit if ...
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0answers
50 views

Trying to replace a Sun 1/2 amp mini fuse

I am trying to replace a fuse on a board and I'm a novice. The fuse itself is labeled "Sun 1/2 amp" and looks similar to ceramic, although I am not certain of this. It is held to the board by 2 leads. ...
0
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1answer
421 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 ...
8
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3answers
371 views

Why might a multimeter ask for “wrong” fuse sizes?

Why might a multimeter ask for the "wrong" sizes of fuses? On the front of my Fluke 87 multimeter, the two probe ports for amperage are labeled as fused at 10A (max) and 400mA (max). When opening the ...