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(http://electronics.stackexchange.com/) SE site.

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8
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3answers
197 views

Verifying radiation measurement smart phone applications

I've stumbled upon a strange class of Android applications lately. (And I'm sure such applications are available for other platforms too.) These apps claim the ability of detecting radiation. The ...
2
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4answers
104 views

what could generate a high-pitched whine in electronics where the frequency depends on the current?

So I was operating a Laue machine recently which generates x-rays and fires them at a sample, and I noticed that there was a high-pitched whine coming from the instrument (nothing abnormal, just ...
2
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1answer
37 views

Calculating Boltzmann constant using semiconductor

My task from the latest laboratory exercise in physics is to calculate Boltzmann constant from known temperature, current and voltage. We were given this circuit: By changing the resistor value, I ...
0
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1answer
52 views

Are there any radiation emitted from the cameras? [closed]

Do modern video cameras emit any kind of radiation? If so, what range of frequencies they have? I was wondering if we can detect any radiation so any help regarding detection will also be appreciated. ...
0
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0answers
25 views

How to make LC tank circuits oscillate continuously? [migrated]

An LC tank circuit produces oscillations, when the capacitor is charged and connected to the inductor, but the oscillations decay gradually. How to make it continue, i.e. oscillate continuously? I ...
0
votes
2answers
218 views

If we connect a block of p-type semiconductor only to a positive terminal, will it become positively charged?

Connect the positive terminal of a battery to a piece of p-doped semiconductor, say, silicon doped with boron. Will the terminal pull electrons out of the doped silicon, or equivalently, inject holes ...
4
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4answers
7k views

How does power consumption vary with the processor frequency in a typical computer?

I am looking for an estimate on the relationship between the rate of increase of power usage as the frequency of the processor is increased. Any references to findings on this would be helpful.
0
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0answers
6 views

What is this circuit gain when set is in [0,1]? [migrated]

When set is 0 or 1 I could find it. It either attenuates by 10 or amplifies by 10. However, the circuit becomes different when it is between 0 and 1.
0
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1answer
43 views

How can monitors display a sharp image, if light travels in all direction?

The question title might be a misnomer, help me improve it. My question is, from my understanding, a light travels in all direction from it's origin point. Also I assume that in the example of a ...
0
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3answers
39 views

What stored charges do in a capacitor? [closed]

Why does a fan need capacitor? Capacitor is just providing charges to fan but it can be accomplished without it by directly connecting fan with electric supply. Which other appliances need capacitor?
1
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1answer
36 views

What will be the effect of placing a light source very close to a photodiode?

What will be the effect of placing a photodiode really close to a laser source and what should be the appropriate distance between a light source and photodiode to get maximum output current?
1
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2answers
49 views

How does electrostatic force affect electronic devices?

How does electrostatic force generated by two seperate plates having opposite charges affect electronic devices? I know that magnetic fields have some harmful effects to electronic devices but I am ...
0
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2answers
54 views

What temperature will create amorphous TiSi?

At what temperature will create amorphous TiSi? I think it's around 500 Celsius but I'm not sure.
0
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1answer
39 views

Is a motor HP torque directly proportional to the increasing HP among identical motors?

Say you have three motors: Motor 1 = .10 HP with x torque, performing task A Motor 2 = 1 HP with y torque, performing task A Motor 3 = 10 HP with z torque, performing task A If the motors are the ...
0
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0answers
28 views

Does the Shockley Diode Equation hold in a dynamic circuit?

Consider the following simple photodiode circuit: I've created a real-life version of this circuit, and I've detected that $I$ is oscillating: $$I(t)=I(t+\tau)\tag{$\tau\approx ...
1
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0answers
42 views

Remote EEG Detection / Reading

I recently noted that Phillips, Accenture, and Emotive grouped together to create a proof of concept that would assist ALS patients to gain greater control of their lives through brain, voice, and eye ...
1
vote
1answer
13 views

Generator phase noise influence on its averaged signal

I need to estimate averaged signal of a generator with known phase noise and the amplitude noise can be neglected. The averaged signal of the generator is expressed as: $$ \langle A\exp{i(\Omega t + ...
0
votes
1answer
42 views

Am I solving this basic Kirchoff's current law and Ohm's law problem correctly?

After moving onto some of the practice textbook exercises in the section covering Kirchhoff's current law and Ohm's law, I came across a problem which evades my best attempts at solving it. Using ...
0
votes
1answer
39 views

What's wrong with this solution to freshman textbook example for Ohm's law and Kirchhoff's current law?

I'm a freshman taking an introductory course on circuit theory and I've run into a bit of trouble working through a textbook example practice problem. Unfortunately, it only lists the answer and not ...
2
votes
0answers
55 views

Really Struggling in electronics. What to do? [closed]

This is my first post so please go easy on me. Okay. Let me introduce myself. I am a first year undergrad CS student who has to study basic electronic course for one semester. As the title says, I am ...
6
votes
6answers
9k views

What would be the effective resistance of the ladder of resistors having n steps

I'm a tutor. This is a high school level problem. In high school, every one have might have solved a problem of effective resistance of a ladder of resistors having infinite steps. Now the problem is ...
1
vote
1answer
37 views

why some elements of same group cannot be used for doping semiconductors?

15th group elements like As, Sb, P can be used for doping whereas N and Bi cannot be used for doping even though they too belong belong to 15th group. Why ?
7
votes
1answer
4k views

How does a digital radio tuner work?

I believe I understand how tuning a radio with an analog tuner works: turning the dial physically changes the length of the antenna, which determines which broadcast wavelength will resonate in the ...
0
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0answers
40 views

How can a paper battery behave like a capacitor?

I was trying to understand how paper batteries work and came across some explanations saying that the paper battery can also behave like a supercapacitor on account of its ability to discharge and to ...
1
vote
3answers
141 views

How does Ohm's law apply to superconductors?

As radio amateurs we've all learned the various relationships of power, voltage, current and resistance as expressed in Ohm's Law. My question relates to the following simple circuit showing an ideal ...
1
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0answers
63 views

Concepts in Gabriel Kron's later papers

Gabriel Kron was an important research electrical engineer known for applying differential geometry and algebraic topology to the study of electrical system. Towards the end of his career he published ...
4
votes
1answer
60 views

What does a MEMS gyro measure during off-axis rotations?

I've been working with MEMS gyroscopes in hobbyist projects for years—but it's recently come to my attention that I don't have any principled understanding of what rotation rate measurements ...
1
vote
1answer
37 views

How do I calculate motor efficiency from voltage, current and RPM?

I have a setup where a motor is spinning at a constant (known) RPM, under no load. I know the power going into the motor (voltage * current), and I can find out the rotational kinetic energy of the ...
1
vote
1answer
98 views

Calculate TEC efficiency

I am currently doing a small experiment using a Peltier to cool 250ml of water. My aim is to achieve the cooling of 250ml from 23degC to 8degC in under 20minuets which I have done by strapping the ...
1
vote
0answers
46 views

How do universal battery chargers work [closed]

How does a universal battery charger, such as this one work, i.e. how does it know what voltage, current and polarity is appropriate for the battery inserted? Do batteries have some form of protocol ...
3
votes
2answers
128 views

Why do batteries become weaker

I was thinking about my phone (Sony Xperia Z2) and when I put it to charge and remove it, the phone says "Please remove the charger, to save battery life," which is very intuitive question for a ...
6
votes
3answers
12k views

Why can electricity flow only in one direction through a diode?

A few days ago I was soldering a small thing which contained a diode, a battery and some other useless things. Unfortunately, I soldered the diode reversed and it didn't work. When I reversed it ...
2
votes
1answer
25 views

Why Microchannel Plates can be operated only in vacuum?

Why it is said that the Microchannel Plates can be operated in vacuum? What is the maximum pressure in which it can be operated? Also, while it is not operating, should it be kept in vacuum? Is this ...
1
vote
3answers
132 views

Is it possible to produce gamma radiaton using radio emitter?

As in the title, I'm wondering is it possible. I think it is possible, because we have powerful enough radiotechniques and gamma radiation are just EM waves, not particles. However I think is ...
3
votes
3answers
51 views

Real silicon atom structure?

Text books say that a pure silicon atom has four electrons in its outermost orbit. How do the scientists know it has four electrons?
1
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0answers
28 views

A voltage-controlled oscillator? [closed]

I already apologize for my medium english... I'm a french guy, not really gifted to recognize electronic circuits : In fact, I need to identify a circuit from is function. So, here is the block ...
0
votes
5answers
4k views

Current through the reverse biased junction in transistor [closed]

A transistor is a three terminal device. One terminal is called emitter, one collector and in between them is base. Now, during biasing the junction between emitter and base is made forward biased and ...
15
votes
4answers
1k views

What's the physical meaning of the imaginary component of impedance?

As you know, impedance is defined as a complex number. Ideal capacitors: $$ \frac {1} {j \omega C} \hspace{0.5 pc} \mathrm{or} \hspace{0.5 pc} \frac {1} {sC} $$ Ideal inductors: $$ j \omega L ...
0
votes
0answers
15 views

What determines the frequency output of a Barkhausen-Kurz tube?

I looked at the wikipedia entry and it doesn't give a very detailed or thorough description of the principles of operation of Barkhausen-Kurz oscillator triodes. But I do wonder if it is physically ...
1
vote
2answers
151 views

Electrical analogy for stress and strain

It feels like the relation between stress and strain (and other mechanical properties) is analogous to that of some electrical properties (voltage and current?). I'm comfortable with electrical ...
0
votes
0answers
53 views

Charge Amplifier response and frequency response [closed]

I am getting ready for my final and have completed everything on my study guide except for two questions I cannot figure out. Here is the first question: I have gone through all my lectures and ...
1
vote
1answer
71 views

How big was the first transistor?

The first working point-contact transistor made in 1947 by Bell Labs. I'm looking for specific dimensions, all I've been able to find is "Fits in the palm of your hand".
1
vote
3answers
742 views

Would connecting p-type and n-type semiconductors work as a diode?

If we placed p-type and n-type semiconductors close enough to be touching (see fig. 1), would this arrangement work as a diode? ...
6
votes
1answer
821 views

How do Zener diodes maintain the potential across their terminals?

My physics book has a topic about Zener diodes being used as voltage regulators in the reverse bias. Well, I'm curious to know how does a Zener diode maintain the potential across its terminals after ...
2
votes
1answer
262 views

Why the electric potential of earth is zero?

For a localized charge distribution the potential is set to zero far away from the charge distribution (at infinity) Now, when grounding a conductor, i.e. connecting it to Earth, it is said that we ...
1
vote
2answers
83 views

Can you replace the backlight of a thin film transistor (TFT) with a mirror?

I basically know how TFT' displays work. They have on both sides a polarizing foil, in 90 degrees with the crystals in the middle modifying which light particles should pass through or not. The light ...
2
votes
1answer
36 views

What do I get when measuring on top of metal/insulator/metal by kelvin probe?

I am using a macroscopic Kelvin Probe for work function measurement. There's one confusing condition. If I measure a trilayer thin film stack with a structure of ITO(bottom)/PMMA(100-200nm)/Al(top), ...
1
vote
4answers
1k views

When does Thevenin's theorem not apply (modelling a power source with a ohmic internal resistance)

Most physics text books say that a power source can be modelled as an EMF with a internal resistance. This is also know as Thevenin's theorem or Norton's theorem. However I have read in some sources ...
4
votes
1answer
570 views

Turn-on delay time for Laser diode

Do you know any simple explanation on the reason why the turn-on delay time on a laser diode is reducing while we increase the bias current? Turn on delay,is the time that the laser needs from the ...
1
vote
1answer
73 views

What is the speed of electrons in a transistor?

What is the average speed of an electron in a MOSFET transistor, and how can you calculate this? I've heard people throw terms such as "drift velocity" and "Fermi velocity" around, but I've never ...