GPS NMEA, Failover Circuit upgrade attempt.

[chopnhack]

I have read their datasheet and it says that they have an 80 ohm resistance

Where did you find the datasheet? The one I found doesn't show your particular current level, but all the other models show much lower resistances.
https://www.elsin.ru/pdf/JK250series.pdf

 

[HellasTechn]

I've used these kinds of fuses before, to protect a large CPU PCB for a stairlift and other things. They're very useful as they allow you to perform maintenence on the board without changing the fuse. If you haven't fixed the fault at least you don't waste fuses.

They break the circuit very quickly in the event of a short circuit.

Good to know they actually work.
I dont really care about wasting fuses but what is important to me is that in case of too much current draw, i will not need to open the device and replace the fuse.

Where did you find the datasheet? The one I found doesn't show your particular current level, but all the other models show much lower resistances.
https://www.elsin.ru/pdf/JK250series.pdf

actually the datasheet is this one :

http://pdf1.alldatasheet.com/datasheet-pdf/view/565881/UNSEMI/JK250-020U.html

and for a 20ma fuse gives a minimum of 80 ohms resistance

 

[chopnhack]

Good to know they actually work.
I dont really care about wasting fuses but what is important to me is that in case of too much current draw, i will not need to open the device and replace the fuse.



actually the datasheet is this one :

http://pdf1.alldatasheet.com/datasheet-pdf/view/565881/UNSEMI/JK250-020U.html

and for a 20ma fuse gives a minimum of 80 ohms resistance

I see it now!

 

[HellasTechn]

They break the circuit very quickly in the event of a short circuit.

Now this is what i have noticed about theese fusess.... THey do not break the circuit in case of over current but they tend to keep current at the same level...

Example i short my psu through a 50ma fuse at 2 volts and it restricts current to 50ma when i turn voltage up it keeps current at 50ma and gets hotter. I think it acts like a variable resistor.