All Questions
30 questions
3
votes
6
answers
879
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 ...
0
votes
0
answers
52
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 ...
5
votes
1
answer
456
views
Overcurrent protection (at 4A 100V)
On the PCB I'm designing, the total power consumption might be as high as 86W (including output power), with supply voltage between 18 and 75V DC (it is OK not to allow full output power bellow 22V). ...
0
votes
2
answers
513
views
Why don't Arduinos have a fuse on the Vin pin?
I am designing a PCB for an Arduino Nano. I want to protect the Nano from over current and high voltage. In the schematic of the Nano, there is only one fuse at USB Vcc at Arduino Nano Rev3. No clone ...
1
vote
0
answers
713
views
\$ I^{2}t \$ calculation issue
I tried to select the fuse based on this selection guide, but found my calculation for fuse I2t is not practical. Can someone point out the error in my calculation?
The application scenario is a 240V ...
8
votes
9
answers
4k
views
Do I misunderstand fuses?
A statement that I often read here goes: "Fuses protect the wire, not the load."
However, in basically all cases I use fuses, I think they are there to protect the load - I.e. the device on ...
0
votes
1
answer
123
views
Polyfuse for AC line no 10A? [closed]
I have a circuit where I would like to replace standard 10A glass fuses with some resettable solution.
I have looked into polyfuses:
https://lcsc.com/products/PTC-Resettable-Fuses_11042.html?q=poly%...
13
votes
3
answers
4k
views
What would it take to make a PS/2 keyboard interface hot-swap?
A long time ago, I had to service some of the early Compaq Desktop PCs. They used to have fuses on the motherboard that blew when a customer hot-plugged a keyboard.
I found this when googling on the ...
0
votes
1
answer
572
views
Choosing fuse for 2S Li-po
I have a 2S 8000 mAh Li-po battery I want to use as an external power source for my DSLR camera (Canon 7D Mark II). Previously, I failed to power it with a power bank and a DC-DC converter, most ...
0
votes
1
answer
916
views
How to identify the polyfuse used in this RS-485 module
This is the popular RS-485 module found in the market, how can I identify the polyfuse/heat recovery fuse in it? Also its manufacturer or electrical ratings?
0
votes
2
answers
628
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 ...
1
vote
2
answers
534
views
Precision resettable fuses
I am a scientist, and I have found myself needing to interface two disparate pieces of equipment.
I have a precise, automatically controlled current source that I wish to interface to a very ...
1
vote
1
answer
2k
views
What does it mean to trip in PTC Fuses?
Hi I want a current flowing 1A. I don't understand what does it mean to trip?
(Image source - Farnell PTC datasheet)
Does it mean to open the circuit? Should I be looking at a holding current that ...
0
votes
2
answers
1k
views
PPTC Resettable Fuse
I recently bought a few types of resettable fuses, but now I'm a little bit confused using them.
I have bought:
30-UF200 (Hold: 2A, Trip: 4A)
RUEF300 (Hold: 3A, Trip: 6A)
R30400 (Hold: 4A, Trip: ...
3
votes
4
answers
2k
views
Specifications to consider when selecting a polyfuse
I am designing a power supply for a flight controller, and I am finished with the regulating and almost everything else. I want to have a polyfuse on both of my inputs, but I don't know how to pick ...
0
votes
2
answers
197
views
Replacing the fast tube fuse with polymer fuse
I have a simple digital multimeter in which a fast tube fuse, rated at 0.1A and 250V is soldered directly to the plate.
Now, recently this fuse blowed and I have to replace it. Because I don't want ...
2
votes
3
answers
2k
views
Fuse dimensioning guidelines
I’m looking for advice on how close to nominal current draw a fuse should be dimensioned. On the internet I have seen numbers from 125% and to 800% in different applications, which is a rather wide ...
1
vote
0
answers
535
views
Resettable fuse failure
I have a 1.1A, 33V resettable fuse in SMD 1812 package. To test it, I connected a 6A 20V source across it. It went up in a flame that lasted a few seconds. Should I conclude that the fuse is out of ...
3
votes
1
answer
3k
views
24V Circuit Protection - Fuse, TVS Diode, RC Snubber
I have pored over data sheets and read numerous articles on circuit protection. I understand conceptually, but I don’t trust my level of knowledge to implement it optimally. I want to be as specific ...
3
votes
1
answer
2k
views
Using Fuses to Connect Batteries in Series
I would like to create this battery pack, consisting of 13 Samsung ICR18650-26F connected in series. There are balancing leads for balanced charging, and resettable polyfuses connecting all of the ...
0
votes
2
answers
5k
views
How to fuse batteries connected in series?
Is it possible to wire each battery in a series to the next using a fuse wire, so that the individual batterie's max power output is not exceeded?
here is an illustration, suppose each battery had a ...
1
vote
1
answer
2k
views
Alternatives for automotive fuses?
So be I recently asked a question about using a PCB design for a fusebox (link here: PCB design for automotive fusebox?) but since recently come across two other fuse alternatives: PPTCs and ...
4
votes
2
answers
4k
views
Replacing glass fuse with reset button fuse?
Several months ago i made a 10Amper power supply with 5 outputs, each output has a fuse holder for crystal 10A Fuses, they work as intended but its a chore to replace them every time i short them, i ...
8
votes
2
answers
3k
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 ...
3
votes
5
answers
1k
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 computerUSB-...
3
votes
1
answer
477
views
Question regarding fuses
What is the difference between thermal fuse and MOV and polyfuse.Which is faster and also which companies produce polyfuse, especially in Asia.
I have to search for a component that can save my ...
7
votes
3
answers
11k
views
How do I measure startup/inrush current?
I have some small devices that draw 20mA. I'd like to add a resettable (PPTC) fuse to them but I am not sure what value to select.
My thought is I need to find a value that will tolerate the startup ...
5
votes
2
answers
11k
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, ...
14
votes
4
answers
16k
views
How do I choose a fuse? Fusible Links vs Polyfuse?
I realise this is an extremely broad subject area but I need to know how to choose a fuse to protect a circuit.
Recently, a cheap PSU of a friend's blew up quite spectacularly (the two primary ...
5
votes
3
answers
692
views
Are PTC fuses called some other way?
I recently learnt about the existence of PTC fuses, and I'd like to use one for an USB power supply I'm building. I guess there are PTC fuses on the PC side, but you never know.
I went happily to buy ...