Hi,

Is there an electrical component that stops a small current from passing through, but if the current is large enough, is allowed to pass through without destroying the component?

 

There are PTC's and NTC's that do a similar thing.
Did you want to switch when a certain level is reached?
Max.

 

Why do you want do that?
Explain exactly what you are trying to do.
How can the current ever get to be a large current if you stop the small current?

 

Yes... Let us solve the real problem... Not work with what you think the solution is..
So please explain what you are trying to do..

 

Hi,

Is there an electrical component that stops a small current from passing through, but if the current is large enough, is allowed to pass through without destroying the component?

How can there be a current that is "large enough" if the current is being blocked?

You need to explain in much more detail what you are trying to accomplish.

 

If you block a small current, then no current is flowing. If no current is flowing it can never become a large current.
As others said, what are you trying to do?

 

Hi,

Is there an electrical component that stops a small current from passing through, but if the current is large enough, is allowed to pass through without destroying the component?

Not a simple component, but a circuit. You would need to get specific about how much current you were talking about.
Second concern ... if you have to ask the question could you understand the answer?
If we gave you as circuit design could you build it? No insult intended, I don't know your abilities, this being your first post.
Yes, the problems mentioned are a killer. Let's hear the original condition that is trying to be dealt with. If you turn off the circuit at a small current you can't develop a high current.

 

OK, here's a comment from the peanut gallery. I may be entirely wrong on this, but I don't claim to be any kind of expert. Still, I like a challenge. So I came up with this.

Q1 base remains off because there is insufficient current being drawn. Either no load at all or a light load and the current is insufficient to switch it on. But when the load is high enough the current needed to activate Q1 turns it on. Current then passes through R1 & R4, turning the base of Q2 on. Q2 holds the base of Q1 low via R3. R2 prevents C1 from charging too fast preventing the base of Q1 from shutting off before Q2 can go active.

This may not work. Probably won't work. But I'm trying to exercise thought in an area where I'm not familiar with. As is much of my electronics. That's why I'm here. But if this circuit works - or if some modified version will work then I'm confident that the experts here will quickly speak up as to why my circuit won't work and possibly offer a solution that will work. The problem with this is once it's turned on, how do you shut it off? Only a power interrupt will turn it off. OR you can interrupt the base of Q1. I haven't figured that out yet.

So here's my shot at this:

 

Doesn't the flux capacitor work on this principle?

 

No. The whole idea behind the flux capacitor is the eddy currents surrounding the conductors. By passing a current in a - lets assume positive direction, this will result in travel back in time, depending on how much energy and the duration. To travel back to the place you started you must pass current in the opposite (negative) direction in order to move forward in time.

Enough nonsense (from me).

 

There is a semiconductor device called a diac that does this.

https://en.wikipedia.org/wiki/DIAC

https://www.digikey.com/products/en?FV=fff40015,fff80040&k=diac

also on Farnell in the UK

You may also want to look at MOV or TVS.

 

There is a semiconductor device called a diac that does this.

https://en.wikipedia.org/wiki/DIAC

https://www.digikey.com/products/en?FV=fff40015,fff80040&k=diac

also on Farnell in the UK

You may also want to look at MOV or TVS.

The question revolves around "how much current are we talking about?"

 

Still no clarification from the OP.
I sometimes have the feeling that some thread starters throw poorly worded questions with a lack of information at us just to watch us flounder, trying to guess at at the correct answer.

 

Still no clarification from the OP.
I sometimes have the feeling that some thread starters throw poorly worded questions with a lack of information at us just to watch us flounder, trying to guess at at the correct answer.

These people are not engineers. It is difficult to respond on the same level they are. Thus the comment "if you gave to ask the question would you understand the answer?"

 

Spark gaps, tunnel diodes and transistors in avalanche mode (same as DIAC) also come to mind...

 

If you take the question literaliy then a spark gap or diac would not meet the OP reqirement as they depend on voltage. I don't think there can be a solution as a current must be flowing to measure it to set a threashold.

Les.

 

Hi,

Is there an electrical component that stops a small current from passing through, but if the current is large enough, is allowed to pass through without destroying the component?

Are you, perchance, conflating current with other electrical quantities? -- 'Negative resistance' devices (e.g. thyristors, varistors, 'transient absorbers', Zener diodes, tunnel diodes, UJTs, gas discharge tubes, etc), for instance, might be said to 'block' current flow below certain 'voltage' levels -- Unfortunately the laity (including, IMO, most egregiously, entertainment) have fallen into the 'habit' of referring to all aspects of electrical energy as 'current' sans regard to sense, sanity or anything like reason!

Best regards
HP

PS
FWIW it is my guess that your (actual) interest is in regards to transient absorbers or inrush limiters (q.v.)

 

These people are not engineers.

Perhaps not - but they are students (formally or otherwise) and, more to the point, participants whom might reasonably be expected to exhibit a modicum of courtesy - via, for instance, following up their questions!

Perhaps 'dearth of social grace' ≠ 'troll' - Though I assert such to be an 'inequality by fiat' at best!

Respectfully
HP

 

Perhaps the OP feels intimidated by the responses. Maybe they realize their lack of knowledge and is too embarrassed to come back and present themselves again. After all, I did see some mighty big words being used here. Kind of intimidating to me. At least I admit my ignorance on some subjects.

 

At least I admit my ignorance on some subjects.

Ditto! -- IMO pride comes way too high by virtue of its incompatibility with education!

As regards the OP -- I feel the respondents have been more than patient and friendly - IMO his ongoing 'reticence' is nothing short of ungrateful!

Oh! Well! -- I suppose we'll survive another day

Best regards
HP