Questions tagged [electronics]

Electronics is the study of electric circuits and electrical components, and the design of useful devices. Some questions in this tag may be more appropriate for the [Electrical Engineering(https://electronics.stackexchange.com/) SE site.

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How do I achieve 50Hz using an astable multivibrator? [migrated]

So based on the $f=1/1.38RC$ equation I came up with the conclusion that $R$ must be 69000 ohms and $C$ must be 1000uF, is this correct? And I have a side question: If I am charging a capacitor ...
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Could light erase a hard drive?

I have been having a theoretical discussion with a colleague at work. He proposed the idea of a laser being able to erase a hard drive. I know that a hard drive is basically a magnetic disc that can ...
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Terminating Resistor in a B-dot Probe Circuit [closed]

Can someone explain to me how a terminating resistor works in the context of electrostatic noise pickup in a b-dot probe circuit. I am having trouble understanding why placing a resistor is parallel ...
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Why do they keep the street lights on in the morning?

I am sure that almost everyone at least once in their lifetime witnessed some street lights being on even in the morning. I wonder why they keep them on in the morning. Possible Explanations ...
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1answer
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Voltage drop in a forward biased diode

I'm trying to understand why is there a voltage drop when a diode is in a forward bias. From what I understood the PN-junction creates a potential barrier of about 0.7 V for silicon. Now looking at ...
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Kirchhoffs Voltage and Current Law, Single power source, 3 parrallel Circuits [closed]

ive been trying to figure out the simultaneous equations for the below problem, I am useing Kirchhoff current and voltage law. any help with these equations would be great. At the moment, i have ...
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1answer
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Can electric signals be amplified in a simple circuit? [closed]

If a simple circuit is built with an DC source,an output resistor and an input source (I mean transformer or something through which signals can be passed through this circuit),will it work as an ...
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2answers
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How to calculate output resistance for a transistor in common base configuration?

This question more related to my physics practical than a theory question. How do i calculate output resistance if i have the corresponding table for it? I know Ro=...
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1answer
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Does phase of a signal (very low frequency, 0-100Hz) change due to pink noise?

One might experience pink noise when dealing with low frequency signals (0-100Hz). Curious to know whether pink noise has an effect on phase of the signal specially in lowest frequencies 0-10Hz.
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1answer
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Why there is creation of electric field from n-type to p-type in pn junction?

I know that in pn juction due to diffusion the electrons in the n-type semiconductor moves to p-type semiconductor, but I am confused that why electric field is developed from n type to p-type rather ...
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Why are there no brushless motors with more than 3 phases (6, 9, etc.)?

My understanding is that adding phases will (up to a point) add the ability to push more power through a motor (more Amps total, same per individual winding wire), generating more torque for similar ...
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Excess energy in photoelectric absorption

In photoelectric absorption in semiconductors, the threshold energy $E$ of an incoming photon is given by the bandgap energy of the material $E_{bg}$. So for $E \ge E_{bg}$, the absorption is possible....
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Which silicon for semiconductors , chips and so on? [closed]

I think a while ago I heard someone saying (or I read it, can't remember..) that the silicon for our semiconductor industry isn't just simple silicon. More, it is a special type of silicon but I ...
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How can I track the resonance of a tuning fork through a PLL if my phase lag graph is discontinuous?

I am programming a phase-locked loop to track the resonance of a tuning fork so that the tuning fork is always on resonance. This will be used in condensed matter physics through atomic force ...
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1answer
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What are safe voltage differences to connect 2 batteries in parallel? [closed]

I have a OneWheel electric skateboard with a 58V LiFePO4 battery 130Wh (I believe 14s1p configuration). There is a method in practice where owners wire EGO LION battery packs (56v 2.5Ah=14s1p, 5Ah=...
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What is meant by “the current-voltage characteristic was asymmetric and non-ohmic”?

I am currently studying the textbook Light-Emitting Diodes (3rd Edition) by E. Fred Schubert. Chapter 2.1 Compound semiconductors says the following: In 1874, Karl Ferdinand Braun (1874), a German ...
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Number of intrinsic charge carriers in semiconductors

On one hand, my book calls both electrons and holes intrinsic charge carriers of a semiconductor, and on the other, it states the relation x = y = n, where x, y and n stand for the number of electrons,...
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How are the layers of a solar cell stacked together?

Do manufacturers of solar cell use an adhesive to bind the n-type and p-type layers of a solar cell?? Or do they simply rely on the smoothness of the surfaces of the individual layers to contact each ...
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Equivalent Resistance of the Circuit Part [duplicate]

What will be the equivalent resistance of this part of circuit ?
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1answer
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Is there a frequency converting amplifier? [closed]

Frequency conversion means output of the amplifier is at a frequency different from that of the input.
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1answer
47 views

How does a staircase switch work? [closed]

Well, I live in a descent old kind of house with old wiring and connections but a fascinating thing in my house is a 2 way switch (I don't even know if it is called so). The arrangement is like we ...
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1answer
53 views

Relationship between heat transfer and electricity

How can it be proven that the heat transfer through a wall is the temperature difference divided by the total resistance? Can this be proven without using concepts related to electronics for example ...
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Changing Voltage

Today I noticed this happening that while my laptop was connected to the charger and there were small voltage fluctuations in my home, I could hear some clear sounds in my earphones (while they were ...
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1answer
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Reason of saturation region in MOSFET

I can't wrap my head around the circumstance that, somewhen when I increase $ V_{DS} $ the current $ I_{DS} $ will remain constantly. Why is that? https://www.electronics-tutorials.ws/amplifier/...
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Can two electromagnets with the same power source have a force on each other?

In theory, it seems like an obvious yes, so I tried setting up two coils connected in series with opposing B fields. Maybe there's something wrong with my setup, or I'm missing something obvious but I'...
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1answer
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How is Alternating Current (AC) used in Bipolar Junction Transistor (BJT) without ruining its operation?

In a BJT (Bipolar Junction Transistor), say NPN in common base configuration, we forward bias the Base-Emitter Junction and reverse bias the Base-Collector Junction when using a constant DC supply. ...
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How point-contact transistor work?

In December 1947 Bardeen, Brattain and Shockey introduced a device which is considered to be the first transistor. This transistor was point-contact device. So, it used metal-semiconductor junctions. ...
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2answers
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How to know if voltmeter in an electronic diagram connected to a resitance or not [closed]

Greeting. Can someone please explain to me why the voltmeter in this diagram read zero? The problem say beacuse it is not connected to a resistance but I don't know how to tell whether a voltmeter in ...
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1answer
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Why would lamp A be shorted here in this circuit when testing the circuit with a power supply?

I'll really appreciate a response to this question, thanks for considering. Suppose I have this circuit (image from a CIE past paper question): Actual text (image here) in the problem: It is said ...
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3answers
67 views

Why can't the current in a solenoid be changed rapidly?

Why can't the current in a solenoid be changed instananeously? My reasoning is since the current in a solenoid is given by a integral: $$I(t) = \frac{1}{L} \int_{t_0} ^{t_f} V_Ldt$$ then if $t_f = t_i ...
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2answers
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What is an isolated system in capacitive circuit?

Does isolated system here means that the plates of capacitor need not be connected to terminals of a battery?
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1answer
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Why Diode breakdown allows heavy current with a constant potential, but conductors fail to do so?

A conductor, metallic is considered to be containing a sea of mobile electrons. When a diode breakdown happen, we actually have a lot of electrons inside the depletion region that are inside their ...
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1answer
37 views

What is the purpose of a resistor in an OR gate?

What is the purpose of a resistor in an OR gate? Isn't it useless since the gate works even if the resistor is absent?
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1answer
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Came across a circuit with current flowing from Low to High potential across a resistor (electrons moving from high to low potential)

This is the circuit of small signal analysis for a BJT amplifier. The current shouldn't flow at all. How is it even flowing ? I'm attaching the snap shot of this particular moment from the video ...
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1answer
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Regarding the quantum nature of floating gate transistor - tunneling, coherence, spectrum

In a floating gate transistor, the gate is electrically isolated. I have a few questions regarding the quantum nature of this device: It is sometimes mentioned that, to store or deduct charges from ...
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1answer
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Parallel grouping of batteries

While studying 'Parallel grouping of batteries with internal resistance' I came across its derivation and found that the equivalent emf to be Σ(E/r)/(Σ(1/r)) Why didn't we take the equivalent emf as ...
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2answers
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What do capacitors actually do? [closed]

I’ve read answers on Quora about why capacitors are used, and they all pretty much said they store charge, or filter out specific frequencies. But what does that actually mean? What do you achieve by ...
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1answer
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Potential drop across a dielectric capacitor with battery

I have a capacitor (C) connected to a battery of emf 100V. Hence potential drop across my capacitor is 100V. Now I introduce a dielectric between the plates of capacitor which increases the ...
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1answer
33 views

Radiation Within a Faraday Cage - Can It Escape?

so we all know that the Faraday Cage prevents most EM radiation from entering the Faraday Cage. But what about, if we place radiation within the Faraday Cage - can it escape outside? I sort of recall ...
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1answer
49 views

What is the point of using an inverting amplifier in a circuit? [closed]

This may be a simple question to most of you, but I'm having trouble understanding the concept behind the use of an inverting amplifier. What is the purpose of using an op amp in an inverting ...
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1answer
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Parallel or series circuit in Delta-Wye transformation

in the transformation from a Wye (star) to a delta (triangle) resistor network it is said that if we want to know the "resistance" between points $N_1$ and $N_2$ ($N_3$ should be ...
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What are these white pellet in my speaker used for? [closed]

These are the pics of the speakers in my surface laptop. What are these white pellets used for. Similar pellets can be found in many tiny speakers of iPhones and Samsung phones.
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Coupled Coils: direction of the magnetic flux

Reading the description of the dot convention, I have found that it makes use of the direction of the magnetic flow: The corresponding terminals are those which, when the current enters through them, ...
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2answers
48 views

How to show connection between measured data (sound in $\rm dB$) and the size of speakers? [closed]

How can we relate the measured data of speakers with its SIZE (speaker)? I have the data on white noise and pink noise (FFT and 1/3 octave), I'm a bit confused about how to show the relationship (...
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0answers
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Mobility of electrons vs holes in semiconductors (intrinsic vs extrinsic)

I was reading my class notes and it was written that electrons are more mobile than holes because the effective mass of electrons are lower than that of holes. (μ=eτ/m*) I checked online to find the ...
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3answers
111 views

How hammering my TV remote make it working?

I often do this while my remote battery gets low, I just hammer my TV remote two of three times. I have seen this to be work with other devices. But I never bother thinking about how this makes things ...
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10answers
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Why does a capacitor act as a frequency filter?

What is it about a capacitor which allows it to filter frequencies? I understand the construction of a high-pass RC filter, and the mathematics behind it, but I'm struggling to find an explanation of ...
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2answers
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Can someone explain me the following line: “The RC circuit averages past history at the input with a weighting factor of e−Δt/RC.”

"The RC circuit averages past history at the input with a weighting factor of e−Δt/RC."

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