Hey guys,
I have been trying to source a fuse to work at upto 3 amps on a 12v dc circuit and a 1 amp fuse for another 12v circuit. A quick search on ebay and i found these surface mount ones.
Couple of questions. Would the 32V/63V mean 32VDC and 63VAC? Would this mean it would be fine for a 12v dc circuit?
Are there any through hole fuses anyone could recommend that would suit what i need? I find soldiering small surface mount components allot harder to work with.
Thanks
In Oz, Jaycar, Altronics, RS Components all sell M205 fuses and PCB-mount fuse-holders, if size isn't an issue.
Jaycar, (fuse-holders near the bottom of Page 1):-
Cylindrical Fuses & Holders
32V/63V probably mean 32VDC and 63VAC but hard to say for sure. It's e-bay. At any case it would be fine for 12V circuit. Through hole PTC fuses exist, e.g.: http://www.tme.eu/gb/katalog/#id_category=100132&page=1&s_field=artykul&s_order=ASC
OldSteve:
In Oz, Jaycar, Altronics, RS Components all sell M205 fuses and PCB-mount fuse-holders, if size isn't an issue.
Jaycar, (fuse-holders near the bottom of Page 1):-
Cylindrical Fuses & Holders
Was thinking a fuse holder would be good, but yeah the size thing would be an issue as the pcb isn't very large.
Budvar10:
32V/63V probably mean 32VDC and 63VAC but hard to say for sure. It's e-bay. At any case it would be fine for 12V circuit. Through hole PTC fuses exist, e.g.: Electronic components. Distributor, online shop – Transfer Multisort Elektronik
They look good, i may have to see if i can source them somewhere closer to or in aus. I'm looking at buying a fair few probably around 50
jeffez:
Was thinking a fuse holder would be good, but yeah the size thing would be an issue as the pcb isn't very large.They look good, i may have to see if i can source them somewhere closer to or in aus. I'm looking at buying a fair few probably around 50
They're commonly known as polyswitches or resettable fuses. (Unlike a traditional fuse, they're self-resetting when the overload is removed.)
Here in Oz, RS Components stock them:-
Wire-ended resettable fuses
They have free courier delivery for online orders.
OldSteve:
They're commonly known as polyswitches or resettable fuses. (Unlike a traditional fuse, they're self-resetting when the overload is removed.)Here in Oz, RS Components stock them:-
Wire-ended resettable fusesThey have free courier delivery for online orders.
Great thanks. So is using the resettable polyswitch ones the best/common way to go? I don't mind using fuses that aren't resettable if they happen to be cheaper. Given the volume of them i'd be after, i'd have to take cost per fuse into account.
jeffez:
Great thanks. So is using the resettable polyswitch ones the best/common way to go? I don't mind using fuses that aren't resettable if they happen to be cheaper. Given the volume of them i'd be after, i'd have to take cost per fuse into account.
That's really a decision only you can make.
An M205 glass fuse is 20mm long x 5mm diameter. Allow a little more for the holder.
The 3A polyswitch is a different shape, but 28.6mm high x 23.9mm wide x 3mm thick. (Not really smaller than the M205 with holder in this case.) Polyswitch size varies with current and voltage rating.
Looking quickly at the listings, a 3A 72V polyswitch from RS is 65c and free delivery, a 3A M205 glass quick-blow fuse from Jaycar is 40c, plus a couple of cents for the holder. With Jaycar, you also have to add postage, probably about $6 to $7 for the order.
The choice is yours. 
OldSteve:
That's really a decision only you can make.An M205 glass fuse is 20mm long x 5mm diameter. Allow a little more for the holder.
The 3A polyswitch is a different shape, but 28.6mm high x 23.9mm wide x 3mm thick. (Not really smaller than the M205 with holder in this case.) Polyswitch size varies with current and voltage rating.
Looking quickly at the listings, a 3A 72V polyswitch from RS is 65c and free delivery, a 3A M205 glass quick-blow fuse from Jaycar is 40c, plus a couple of cents for the holder. With Jaycar, you also have to add postage, probably about $6 to $7 for the order.
The choice is yours.
Given the size constraints i reckon ill have to go with the small surface mount fuses. I found this which shows that the 32V rating is for DC so it should be fine for my 12V boards.
One good thing i can take from this is learning about polyfuses. The funny thing was that all the fuses i found are either to big or extremely small like the surface mount ones lol
I was almost going to go for something like these ones until i noticed they are 63mm long! 
http://www.ebay.com.au/itm/20-Pcs-AC-125V-250V-3000mA-Time-delay-Slow-Blow-Axial-Leaded-Fuses-3-x-62mm-/191680274842?hash=item2ca108e19a:g:gtwAAOSw3ydV5pY7
One good thing i can take from this is learning about polyfuses.
A polyfuse can be very slow to blow when the current is close to the rating. A blow time of 100 seconds is common.
They can take up to 24 hours to recover once blown.
Repeated blowing wares them out.
So they are not as good as they first may seem.
Your question of "cost" can be a tough one - if it is in a simple project at home that is easy to get to a simple replaceable fuse is fine. If it is something out in the field somewhere that would take significant effort to get to when you need to replace the fuse, perhaps the poly resettable one would be better (although if it was not a simple overload, you would have to go out and fix the problem first anyway). There can be many factors that determine "cost", not just the $$ of the part itself.
Littlefuse make some really nice surface mount fuse holder. I've used these in the past.
http://m.littelfuse.com/products/
Ian.
Grumpy_Mike:
A polyfuse can be very slow to blow when the current is close to the rating. A blow time of 100 seconds is common.
They can take up to 24 hours to recover once blown.
Repeated blowing wares them out.So they are not as good as they first may seem.
That was my finding aswell. Though an overload would be very rare to occur, over time the reliability of a polyfuse could be a concern and may want replacing anyway after multiple trips.
gpsmikey:
Your question of "cost" can be a tough one - if it is in a simple project at home that is easy to get to a simple replaceable fuse is fine. If it is something out in the field somewhere that would take significant effort to get to when you need to replace the fuse, perhaps the poly resettable one would be better (although if it was not a simple overload, you would have to go out and fix the problem first anyway). There can be many factors that determine "cost", not just the $$ of the part itself.
Since in my case a blown fuse wouldn't be hard to get access to i'll just use a regular fuse, though i am looking into if theirs a mount that can hold the tiny surface mount fuse instead of having to solder them on.
ian332isport:
Littlefuse make some really nice surface mount fuse holder. I've used these in the past.http://m.littelfuse.com/products/
Ian.
These look good. I may go for these or if they have holders that would hold the SMD 1206 fuses from the ebay links i put up, that'd be even better.
