# Tag Info

Accepted

### Measuring current with a multimeter - What did I do wrong?

You placed an ammeter in parallel to a voltage supply, which created a short circuit through the meter and most likely blew the 10A fuse in the ammeter socket. What you want to do is put the meter ...
• 1,330
Accepted

### Do you need high voltage or current to produce a spark?

You need a high voltage to produce a spark through air. There are two ways to get a high voltage. One is to make a high voltage intentionally. The other is that you can get a high voltage ...
• 167k

### I have 5 kV available to create a spark. Is limiting the current to 500 µA as simple as putting a 10 MΩ resistor in series?

Andy's caution about adding a current-limiting resistor correctly might benefit from an example showing how it can be done incorrectly. The 5kV dangerous source might be connected to the apparatus ...
• 25.9k

### Do you need high voltage or current to produce a spark?

Before the spark, there is no current at all, only a voltage (potential difference) between two points. Arc discharge happens when the voltage is high enough to overcome the gap, and then continues ...
• 46.7k
Accepted

### I have 5 kV available to create a spark. Is limiting the current to 500 µA as simple as putting a 10 MΩ resistor in series?

Can I put a 10Meg Ohm resistor in series that has a breakdown voltage and power rating enough to withstand it and be done? Yes you can do that. Multiple resistors in series will help. Haven't worked ...
• 457k

### Do you need high voltage or current to produce a spark?

It all depends on how you define a spark. If burning metal particles count as a spark, you can create one with very low voltages. Shorting a 1.5V AA battery creates such sparks which can be easily ...
• 25.8k

### I have 5 kV available to create a spark. Is limiting the current to 500 µA as simple as putting a 10 MΩ resistor in series?

In addition to the cautionary notes expressed in other answers, keep in mind that typical voltage ratings on resistors are for DC or low frequency AC applied to the resistor. Spark gaps, depending on ...
• 398k

### Will a spark gap transmit a signal an FM receiver can "hear?"

A spark-gap (without a tuning circuit) will generate a broad band array of radio interference and it's likely to produce some crackles in the FM radio's speaker at any unused tuning position. You ...
• 457k

### How far can mains voltage arc in air?

The breakdown voltage of air varies significantly due to changes in humidity, pressure, and temperature. However, a rough guide is that it takes 1 kV per millimeter. Since that's about where arcs ...
• 313k
Accepted

### Will a spark gap transmit a signal an FM receiver can "hear?"

Yes, but not as loud as in an AM receiver. This is why: Broadcast FM uses a wider bandwidth than broadcast AM. That reduces its susceptibility to electrical noise Broadcast FM works at a higher ...
• 21.4k
Accepted

### Voltage required for a spark plug - dielectric constant of air

Compression is key here as Paschen's law is in effect. https://en.wikipedia.org/wiki/Paschen%27s_law Except for close to vacuum, it's a near linear relationship between pressure and dielectric ...
• 14.8k

### Why did a spark occur between my HDMI cable and metal lamp base?

If everything had been working previously in some configuration with the HDMI cable plugged in at both ends then my best guess is that there is a fault in your lamp. Maybe an earth has become detached ...
• 2,392

### Voltage required for a spark plug - dielectric constant of air

So, you are missing several factors: compression ratio means that the pressure is above atmospheric - probably what you assumed with your calculation. The pressure AND temperature is also increased - ...
• 6,539
Accepted

### How can I prevent inrush current from causing sparks when I connect my project to a power source?

The sparking you are talking about is very likely due to what you already said in your question: My Findings: It happens due to the capacitors in my project. So should I fear? If you have a lot of ...
• 77.9k
Accepted

### Arc welding: Why is electric arc preferred over fire for welding?

Arc and glow discharges can generate virtually unlimited power density. Cosider lightning or magnetic confinement fusion reactor heating. Chemical burning has limited reaction temperatures, spreads ...
• 22k

### Will a spark gap transmit a signal an FM receiver can "hear?"

FM radios aren't made to receive AM or pulsed RF. They are generally immune to the kind of interference that a spark gap transmitter would produce. You might be able to gimmick up a spark gap ...
• 71.4k

### How small can a spark-gap transmitter be made?

There's no reason why you couldn't make one that would fit in the palm of your hand or smaller. The output power would likely be less than something where size, weight and power consumption (and ...
• 398k

### Measuring current with a multimeter - What did I do wrong?

You used an ammeter in parallel to a voltage supply, and not in series. This resulted in more current than the ammeter could handle. You have thus blown some fuse.
• 29.9k

### Why did a spark occur between my HDMI cable and metal lamp base?

If you aren't in the US, ignore this answer. Also, be very careful with live outlets. The problem could be a miswired plug. You can buy an outlet tester for a few bucks at a hardware store. They light ...
• 351
Accepted

### Why did sparks fly when testing outlet frequency?

If you drew sparks with only a single probe, it suggests that you accidentally shorted across neutral to hot somewhere on the outlet. Studying and understanding the manual and the limits of the meter ...
• 14.5k

### Why do cables not arc/spark when being removed or reconnected on a car battery terminal?

You get the same spark if you disconnect the ground cable first. The amount of sparking or arcing depends on the amount of current flowing in the circuit. You disconnect the ground cable first and ...
• 10k

### Measuring current with a multimeter - What did I do wrong?

The principles behind your idea were OK. You wondered what the maximum current that the PSU could deliver. So you connected a very low resistance across it (the DMM) to draw the maximum load and to ...
• 23.1k

### Any tricks for finding the path taken by small ESD sparks across a PCB?

Do you have a blank board, no components? That's how we usually do it. Also, what is the source of the kilovolts causing the sparking? Is this your calibrated pulser during an EMC test? Or HV crap ...
• 10.9k

### I need guidance on designing a 2 kV capacitor charging circuit

Not sure what circuit topology that is - it's missing essential parts of both a flyback and a forward converter. First, some numbers. When fully charged to 2 kV, a 50 uF capacitor holds 100 W-s (watt-...
• 20.2k

### Arc welding: Why is electric arc preferred over fire for welding?

We actually use fire, hot gas, for welding about as often as ordinary welding with an arc. Three broad families can be selected: chemical energy to hot gas - torch, arc to hot gas - plasma cutter, arc ...

### Spark Gap in EMP Generator

The spark gap provides abrupt onset of energy movement; depending on how the spark/plasma extinguishes, you may also get abrupt ending of energy movement. The abrupt changes in energy into the "coil" ...
• 34.3k

### Why is this switch sparking?

The switch terminals are highly unlikely to be aluminum. However, the "silver" plating on many switch and connector terminals is often very reluctant to accept solder - it takes extra flux, and some ...
• 59.3k