Fuse for Etched PCB

Hello all,
Because I ruined a very expensive 4D LCD by overpowering the breadboard accidentally, I am now very keen on using a replaceable quick blow protective fuse in my etched PCB design by using a 600 ma fuse inline on a surface mount.
My question is this, does it matter which quick blow 600 ma fuse I use as long as it fits the fuse holder? Specifically, does the rated voltage actually matter in this case, since our input voltages are so small and I am more interested in the rated milliamperage.
Thanks in advance.
houdinihar

Besides the rated current and the i/t characteristic there are two parameters that affect a fuse

  • Maximum short circuit current determined by voltage and impedance of voltage source
  • Maximum voltage

Unless you power your circuit from a car battery you will be within safe limits on these

Hi, what is the voltage required to power the LCD, if you fried it , it was probably because of high current due to too high a supply voltage.
Your best protection would be shunt voltage protection circuit to go with the fuse you are installing.

Tom.... :slight_smile:

Take a look at "polyfuses" a better option than replaceable fuses.

Mark

Are "polyfuse", i.e. PTC, quick blow?
I suppose you can select one with a very low Time to Trip:

Hmm, links are still posting funny.

A fuse won't hurt but a fuse rarely protects solid state electronics... It's very rare to find a blown fuse where there isn't something else blown (shorted) that caused the fuse to blow.

The fuse is usually there to prevent a fire (stopping heat build-up by stopping current flow) or to protect the power supply after a component has failed.

There's an old joke about, "The transistor blew, protecting the fuse", but in reality, usually the transistor shorts and then the fuse blows too.

Because I ruined a very expensive 4D LCD by overpowering the breadboard accidentally,

Sometimes this stuff happens when designing, prototyping, and debugging... Sometimes it happens in production too. It's less likely to happen if you are experienced. And, with expensive parts you can be extra careful and check your voltages & connections, etc., but sometimes it still happens. (And, use a ground strap at a grounded workstation so you don't damage the parts with static discharge.)

houdinihar:
Hello all,
Because I ruined a very expensive 4D LCD by overpowering the breadboard accidentally, I am now very keen on using a replaceable quick blow protective fuse in my etched PCB design by using a 600 ma fuse inline on a surface mount.
My question is this, does it matter which quick blow 600 ma fuse I use as long as it fits the fuse holder? Specifically, does the rated voltage actually matter in this case, since our input voltages are so small and I am more interested in the rated milliamperage.
Thanks in advance.
houdinihar

The board got damaged because you shorted something or you attached the wrong voltage to it.
You can have a two thousand amp power supply powering an Arduino and things will work just fine.
A fuse will not stop YOU from damaging the board.
Or there is a circuit design flaw.

holmes4:
Take a look at “polyfuses” a better option than replaceable fuses.

Mark

Hi everyone. I appreciate all the feedback.

Mark, I have looked at several different resettable fuses in the mA rating I need and from what I see they are frequently rated in seconds for Time to Trip (TTT)." Any fuse rated in seconds for TTT would be disastrous. Would be just as good as not having any protection onboard. And I did check to be sure they weren’t milliseconds and they aren’t.
On the other hand there were several that were surface mount that actually may work, but these are so small, like 2x 3mm, that it may be hard to work with, and none of these had through hole fittings to solder to making it even more difficult, although their TTT are better by a long shot, and definitely some of them were in the millsecond range.
Mark, any suggestions on getting these little babies safely soldered to my etched PCB?

TomGeorge:
Hi, what is the voltage required to power the LCD, if you fried it , it was probably because of high current due to too high a supply voltage.
Your best protection would be shunt voltage protection circuit to go with the fuse you are installing.

Tom… :slight_smile:

Voltage to power the LCD is only 5V and a few hundred milliamps. Yes indeed Tom, it was definitely higher current and voltage because I plugged in my laptop recharger to the breadboard barrel receiver-they definitely fit. You know, the power supply from the larger laptop recharger look almost the same as the little bitty one I had close by which I should have used. But let me tell you, it was all over faster than I could react to my mistake.
Tom, I did more research on the ‘shunt voltage protection circuit’ and I like that. Very simple in conjunction with the fuse, and the circuit is simple to lay out. Seems like that could be a good working solution I could live with.

I appreciate all the posts relating to this problem I created. Thank you all.
houdinihar

The one thing I would recommend is place a diode from the power supply input to ground in reverse biased connection. It will blow your new fuse if you accidentally apply power backwards.
Or if there is a regulator on the board, place a diode in series with the power input as seen on the UNO schematic.

LarryD:
The one thing I would recommend is place a diode from the power supply input to ground in reverse biased connection. It will blow your new fuse if you accidentally apply power backwards.
Or if there is a regulator on the board, place a diode in series with the power input as seen on the UNO schematic.

Hello Larry,
Since I am interested in using the 'shunt voltage protection circuit'

which already uses a zener diode in reverse bias, would having a second non-zener diode reverse biased to ground be necessary here?
BTW, there is no regulator onboard because I am normally using a regulated power supply.
Thank you.

houdinihar