short circuit detector

[ratstar]

got another one for u dudes to gawk at the insane simplicity. =)

I replaced the picture for a better one, more descriptive and in voltage divider mode instead of current divider to save overloading the led.

 

[Harald Kapp]

What is your power supply going to be?
With only 1 Ω in series with the LED you'll need veeery tight regulation of that supply otherwise the LED will burn through quickly and your "detector" will show a permanent short circuit.

 

[ratstar]

I think a 9v battery will do.
I can see u understand the circuit, because of what you said.

 

[Harald Kapp]

9 V to an LED with 1 Ω series resistor will result in ~7 A current.
Don't worry about draining the battery: The LED will burn through much quicker.

 

[ratstar]

but its 4.5 volts cause its in a voltage divider, and you can light an led off a battery with no resistor fine, with the volt reduction I think would be about safe.

 

[Harald Kapp]

but its 4.5 volts cause its in a voltage divider

Before you edited your image there was only one 1 Ω resistor, you "secretly" added a second one.
Even with two 1 Ω resistors current through the LED will be ~ 3.5 A, still way too high.

you can light an led off a battery with no resistor fine

Yes, once, for a few milliseconds.

with the volt reduction I think would be about safe.

Do not think, do the math -> no this won't work.

 

[ratstar]

The second resistor, makes it a voltage divider, so only half the power of the battery hits the led. it should be safe. but i spose, I could be wrong...

The fact that the invention actually works is not as important as the led frying with the wrong resistance, is it.
U guys help keep my work safe from plagiarists, thankyou.

 

[AnalogKid]

U guys help keep my work safe from plagiarists,

With this circuit, I don't think that's a problem.

ak

 

[ratstar]

Why? it cant be because it doesnt work, because it does.
Is it because its so easy everyone already knows?

Have a look at this circuit on the internet-> (these guys dont know...)

https://www.instructables.com/Short-Circuit-Detector-Part-1/

Its overcomplicated, and I doubt it even works.
You guys are lucky you have me here to point out these things to you. (im sorry if it offends the ego a little tho...)

 

[Harald Kapp]

You guys are lucky you have me here to point out these things to you. (im sorry if it offends the ego a little tho...)

Are we? Or are you lucky to be still here?

 

[ratstar]

If I count my blessings (albiet in an unavoidable circumstance.), I guess so.

Im just letting you guys know that a voltage divider is enough to detect short circuits. isnt that clever.

 

[Bluejets]

Wally..??

 

[ratstar]

So u think it isnt true?

 

[Harald Kapp]

U guys help keep my work safe from plagiarists, thankyou.

If you want to keep your "inventions" from being used by others then don't post here. This is a public forum, open for everyone to read.

 

[ratstar]

yes. sneaky business! =) u guys are an enigma to me.

 

[AnalogKid]

Do you mean 'anathema"?

ak

 

[ratstar]

of course not, I love you guys. enigma as i meant, meant someone that is misunderstood by me.

 

[AnalogKid]

Have a look at this circuit on the internet-> (these guys dont know...)
https://www.instructables.com/Short-Circuit-Detector-Part-1/
Its overcomplicated, and I doubt it even works.

It will do something, but not something useful. In this circuit, the beeper is on constantly until the probes are connected to a resistance of something less than 10,000 to 100,000 ohms. At that point the transistors attempt to place a dead short across the battery to turn *off* the beeper.

It is clear from the schematic what the intent of the design was, but he got it wrong. BTW, this is to be expected from "Instructables". If you check the archives of this and other forum sites, you will find that many of his postings are wrong, and some are dangerous.

ak

 

[AnalogKid]

Im just letting you guys know that a voltage divider is enough to detect short circuits. isnt that clever.

Only at the concept level. To us it isn't useful because of the strain it puts on the battery.

ak

 

[ratstar]

Thats understandable. I wonder if that wasnt the case maybe thered be some way to turn finish it off into an ohmmeter but unfortunately doesnt work very well...