Questions tagged [emf]

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EMF radiation from an open AC circuit

When I pass my EMF radiation meter near an electricity cable (a cable that is connected to the home mains), it shows me that there is a radiation. But if there is an extension cable for example, and ...
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DC Shunt Motor Load Loss

I have three DC shunt wound motors in series. Each motor has a coupling to a transmission. I am trying to work out (mathematically, as opposed to intuitively), what happens if the coupling was to drop ...
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When the electric field EMF radiation hits tin foil why does it result in a magnetic field?

I have a cheap Erickhill EMF reader that measures “electric field” and “magnetic field”. I’ve been experiencing an odd phenomena that I can’t quite explain of a electrical sound emanating from a ...
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Identifying strange readings from Arduino EMF detector

Intro and knowledge self assessment Full disclosure, I'm an amateur, and my knowledge of electronics is cursory, and I'm more into computer science. But I bought an knock off arduino kit, and decide ...
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Is it normal to have around 40 V in your body, when touching your plugged, ungrounded laptop?

I have had bilateral shoulder pain and then both arms and hands pain for around 7 mounts, which got much worse when I started working from home, with my laptop. The ultrasound of shoulder muscles ...
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Where are the sensors of the EMF/RF meter on the circuit board?

In the attached photo you can see the PCB of a simple EMF/RF meter. This meter shows, at the same time, the values of the electric field, magnetic field, and power density (see small illustration on ...
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Elaborated difference between static and dynamic EMF

I have seen two sources have contradicting takes on static and dynamic induced EMFS. One source says that Static EMFs are produced by the circuit and magnetic field both being stationary. Dynamic EMFs ...
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How do I calculate the regulation of the generator in a Ward-Leonard system?

I have a DC motor with independent excitation, power by a ward-leonard system. The nominal voltage applied to the motor is 250 V. I have to calculate what regulation(%) to apply to the generator so ...
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Shield EMF from power cable with aluminium foil

There is a big electric cable behind a wall. On the other side, I read around \$2 \mu W / cm^2\$ of EMF at distance about 3 feet from wall. Is there any way to shield this using aluminium foil? I ...
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Hall effect current sensor and proximity to EMI

I am preparing to layout a PCB. I have an ACS723, that I want to use to sense the current going through a relay. In addition to the relay I have a Meanwell IRM-12-20 to supply ac to dc voltage to the ...
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Why aren't homopolar generators more commonly used?

In particular with the advent of HVDC(high voltage direct current). Using mercury(metal), the resistive losses can be greatly reduced. There has even been some experimental research into neon plasma ...
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Cancelling Ripple With A 7555

Friends, I did this once but don't remember the detail. A very sensitive circuit which switches a relatively heavy load. I used a 7555 IC to momentarily blank out any ripple or instability caused by ...
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EMF - DC Permanent Magnet Motor

I am using FEMM to design a dc permanent magnet rotor. I am trying to calculate the EMF that is induced to the rotor. Since each coil has a different position, the induced emf will be different. In ...
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basic differences between voltage and emf?

what are the basic diff between the emf and voltage? is it that the voltage of a battery is emf and voltage is potential diff between two points,and also please give me some suggestion how to take ...
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188 views

A misunderstanding with Faraday's experiment with iron ring

I am learning about electricity and magnetism, and have got some misunderstanding about Faraday's experiments with iron ring. If iron can conduct electricity, why is electricity inducted only while ...
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Stepper Driver signal noise problem (Ground Loop)

I have an BluePill board (Arm Cortex M3 Dev. Board). Also a a4988 stepper motor driver. BluePill is powered from usb of my PC. Stepper motor driver is powered by external power supply which is 220V -> ...
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