# Tag Info

83

How do I describe this circuit? Do you want subjective opinion? Or technical description? Subjective opinion would be: this circuit is badly designed, no matter what problem the designer tried to solve. Technical description would be: it is a battery killer with stand-by indicator.

79

In simple and practical terms, a short circuit is an unwanted or unintentional path that current can take which bypasses the routes you actually want it to take. This is normally a low resistance path between two points of differing potential. For instance: simulate this circuit – Schematic created using CircuitLab In the left simple LED circuit, ...

76

Most commercial IC circuits are isolated from the substrate material by a reverse-biased P-N junction (including CMOS parts). The substrate is usually tied to the voltage expected to be most negative. If it isn't, then that junction becomes forward biased and can conduct a great deal of current, melting metal or heating the junction to the point where it no ...

56

In most ordinary circumstances, 12 V isn't even enough to feel, let alone cause a shock. However, it's really current that you feel and that shocks you, not voltage. So when we say that 12 V is safe, we're making implicit assumptions about the resistance of your skin. Electrically, you're basically a bag of salt water. Your insides have low resistivity, ...

49

Your understanding of how power flows through a circuit needs adjusting. 1. How much power flows through a circuit, and is taken from the battery or power source, depends on how much current flows through that circuit. 2. How much current flows though the circuit is dictated by how conductive the circuit is. If a circuit has a high resistance, it is less ...

47

The best description for this circuit is "How to NOT control a light with a switch." This was clearly not designed by anyone with even basic knowledge of electricity. Or else it was incorrectly "interpreted" or reproduced by someone with absolutely no understanding at all. Obviously, closing the switch will put a DEAD SHORT across the power supply. That is ...

33

"Battery short circuit stress tester". This circuit will allow you to observe how the supply source reacts when short circuited. Also tests the switch under extreme fault conditions as well. An expendable person should be deployed to operate the switch.

31

It isn't just shocks. A battery can push a lot of current through any piece of metal. This could melt a wrench and cause a fire. It could also cause a ring to get red hot and burn the wearer. It is very easy to get a finger with a ring between the positive terminal of the battery and the body or frame of the car. Always remove metal jewelry when working ...

30

Initially, the inductor resists the change of current, making the diode the path of least resistance and causing it to carry most of the current. When the magnetic field in the inductor builds up, the voltage across it decreases as it allows more current to pass. The diode has a forward voltage drop (typically 0.6V) to account for, so it won't conduct any ...

29

Typical cause would be some electrical transient from outside coupled to an I/O pin, which causes latch-up and destruction via the power supply. Proper design of protective circuitry will generally prevent that in situations short of a nearby lightning strike. Power supply transients could also cause it, only a few volts might be enough, but usually that ...

28

Here's a physics-based intro to the EE concepts you're trying to understand. Your questions are answered at the bottom. Everything derives from the flow of "charge" Electronics, as its root word electron denotes, is very much a study of the flow of electrons in a particular system. Electrons are the fundamental "carriers" of charge in a typical circuit;...

27

That high a failure rate is unheard of for a top-quality supplier like Nichicon when properly assembled and operated conservatively. Even for no-name parts it’s not at all usual- one in 10,000 might be plausible, but that’s on the high side. Short circuit failures are very rare for aluminum electrolytics. I did once see a few in a bag of 1,000 from a Taiwan ...

27

The bottom of C2 is not ground. It is connected to the live input by the diodes in the bridge rectifier on every AC cycle. During the negative half-cycle of the incoming AC waveform, the Neutral wire is positive relative to the live wire. The two grey diodes in the diagram below will be conducting for this half cycle, the other two conduct during the other ...

24

Emitter Followers are prone to oscillation with capacitive loading with unity gain and so are complimentary Darlingtons emitter followers in a feedback loop used in PA's. Normally PA's use series with RC shunt snubbers to suppress absorb spurious RF oscillations > 100kHz to dampen them at the unity gain BW frequency of the power amp. However, Yamaha, ...

23

It won't always work, but sometimes you can track down a short with a thermal camera... of course you have to have a thermal camera to do that. Just power the board up and watch very closely through the thermal camera to see if one area of the board gets really hot, it could help you narrow down the area at least.

21

This is a Short Circuit: Okay, that's what I really wanted to put down. Let's see if we can answer your question with the rest of the space. A short circuit is a connection between two elements which you did not intend to connect. In most cases, this behavior is highly unexpected and has a tendency to cause your circuit to behave improperly. One of the ...

21

The capacitor is in fact a short circuit, however only temporarily. When you first turn on the power supply, the capacitor will act like a short circuit during this initial transient phase. There will be a large inrush current as the capacitor charges up (*). Similarly, if you take a fully discharged capacitor, and connect it to a power supply which is ...

20

This circuit is for a buck converter. If you look into the working of the buck converter, this diode is essential for the purpose of voltage conversion. What happens is that, during Toff duration, inductor current cannot change instantaneously, hence, a freewheeling path is required when the transistor inside the IC is switched off. That is why this diode ...

18

WARNING: If "trying this at home" be aware that there is a small potential for significant hazard occurring - see below. What you propose is a viable and useful and potentially dangerous method. I consider it is extremely unlikely that you will harm yourself doing this but need to note that the possibility exists. I would not do this with other than ...

18

The text description is right. A wrench will throw sparks and possibly heat up and melt, that's dramatic. The image, however is wrong. It clearly shows a person and a wrench being electrocuted simultaneously. The picture is wrong on 2 levels: a car battery can't electrocute a human in typical conditions no single source can electrocute 2 targets so ...

18

Current tends to select line with lower resistance. Short circuit resistance is 0 and open circuit resistance is unlimited. The current of lamp when switch is closed = zero then you have no light but when switch is open the current of lamp is (1.5v/100ohm = 0.015A) then you have light like this picture : and something about the battery :

18

You have fallen into a classic XY problem1 trap. However, thanks for briefly mentioning the original issue, as that makes the overall situation easier to understand. You have a genuine problem ("X"): things are not working with the distance sensors. That is not enough detail to help you with the actual problem, but I'll come back to that. You are having ...

17

The short-circuit in red puts the 2 points A and B at the same voltage, bypassing the capacitor C2.

17

Those wires form coils, so are long. Every bit of wire has some resistance, and all those bits of wire end to end result in a significant enough resistance to not look like a "short". These wires shorted across a voltage source is exactly where the stall current of the motor comes from. It is simply the voltage applied to the coils divided by their ...

17

Thanks to many commentators, I was finally able to blow my fuse. The main point is, batteries have a significant internal resistance. Hence, they do not provide a "virtually unlimited current". Hence, there weren't enough current to blow the fuse initially. As Respawned Fluff suggested, I have connected 3 AA batteries in parallel and connected them to the ...

16

As transformers are usually used with AC rather than with DC, there is what is known as inductance $L$, which is a property of a conductor to "resist" the changes in the current flowing in it due to the magnetic fields induced by that current (self-inductance). The magnetic field is "resisting" due to the fact that alternating magnetic field is in turn ...

16

Even a very small gap is sufficient to stop quite a bit of voltage. IPC-2221B would specify 0.6mm for 48V for an exposed gap on a PCB. Breakdown voltage of an air gap is much higher than that-- 48V will hardly start an arc over any non-microscopic gap. Of course if you get conductive dirt or liquid on it, all bets are off. For example, by using plumber's ...

15

If your circuit is drawn correctly, then the current is flowing backwards through the 1.5V cells. This is like trying to (re)charge them beyond their design voltage. It is very bad for them, and yes, they may catch fire. An actual explosion is possible but very unlikely, as the case is designed to vent off the pressure and stop the explosion - and it sounds ...

15

I think people are distracted by the PMOS, but the real reason is a voltage spike when the 24V is connected, due to inductance of the wiring that is even higher when the multimeter is connected, vastly exceeding the max voltage of the LDO. I assume you are using a ceramic capacitor at the LDO input, which is a reason someone may be experiencing this ...

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