# Tag Info

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You might find the Yahoo "home_transistor" group a useful resource. There's also a series of videos on YouTube by Jeri Ellsworth including some where she makes transistors. In one, in particular, she takes the crystal out of a germanium point-contact diode and turns the crystal into a point-contact transistor (much like the Bell Labs transistor.) There ...

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In experimental physics it is required to use electronics as instruments. You must know how they work(amplifiers, ADC's, MCA's etc) in order to fully understand and design an experiment. Usually, you don't need too much electronics(filters, amplifiers, transistors, digital electronics-boolean algebra) is more often than not, more than enough. You need ...

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The key difference between a Zener diode and a normal diode is that the Zener diode has a low breakdown voltage - typically in the few volts range. The breakdown voltage is low because the heavy doping means the depletion layer is very thin, and even at a low voltage the field strength over this thin depletion layer is very high. With a conventional diode ...

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Calling it a built-in voltage is something of a misnomer. People usually think of "voltage" as "what you measure with a voltmeter". So "voltage" is normally synonymous with "electrochemical potential of electrons" (in stat mech terminology) and with "difference in fermi level" (in semiconductor terminology). Under this definition, the built-in "voltage" is ...

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The answer is that the whole circuit is full of electrons. I think you may be thinking along the lines of "if I switch a tap on, the water takes time $v/L$ to reach the end of a hose of length $L$. So, if I switch a light on, the electrons must take analogous time the reach the light". Because the circuit is full of electrons, the energy source shoves the ...

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For a given circuit in a given technology, power increases at a rate proportional to $f^3$ or worse. You can see by looking at the graph in @Martin Thompson's answer that power is superlinear in frequency. $P=c V^2 f + P_S$ is correct, but only superficially so because $f$ and $P_S$ are functions of $V$ and $V_{th}$ (the threshold voltage.) In practice ...

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The complete explanation takes a few lectures - it is simply impossible to provide this amount of information as an answer. Very general explanation: Let's take a look at NMOS transistor (the one shown in the schematic attached to the question). It has 4 pins which you can force potentials on: Gate Bulk Source Drain In order to understand how the ...

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FORWARD BIAS OF A P-N JUNCTION As the electrons move towards the positive terminal and the holes towards the negative, they will come to the depletion layer. This is a very narrow layer around the junction (i.e. around the interface of the two semiconductors.) In the depletion layer, electrons and holes can recombine, but the recombination rate is not high ...

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Very roughly there are two different processes at work: diffusion and drift. Drift is the motion of the charged particles induced by a field (either the applied voltage or the field in the depletion region.) Diffusion is a function of the width of the depletion region. Drift is not. Drift is a function of the number of minority charge carriers near the ...

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The light output of a LED is pretty linear with the current through it, over its normal operating range. Light does usually drop off from linear with current at the high end. Sometimes that high end is not included in the normal operating range, so the graph you see in the datasheet will be linear. Common T1-3/4 20 mA indicator LEDs are usually linear ...

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I have a couple courses in the atomic nature of analog and digital electronics next year. I'm in Engineering Physics, so I'm not exactly sure which side that confirms, though the courses are in the physics department. Eng Phys has its own courses as well, so if the physics department has these courses then I assume physics majors also have some use for ...

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A pn junction is one piece of a semiconductor that receives n-type doping in one section and p-type doping in an adjacent section. If you simply stick two p-type and n-type semiconductors to each other by hand, it will not behave as a diode. The main reason that a pn junction can behave as a one-directional device is it's built-in potential. Upon formation ...

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The fundamental reason for this is that light is quantized. If it wasn't for this, it would in theory be possible to scale down any camera to an arbitraily small size. However, as a camera is scaled down, less light will enter it and therefore fewer photons. As the number of photons hitting a pixel goes down, the shot noise goes up (the signal-to-noise-ratio ...

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The analogies may be built in various ways – similar simple mathematical relationships like $U=RI$ are among many of them – but I would choose the analogy consistent with the Czech language where "napětí" [nuh-pyeh-tyea] means both "voltage" and "tension". I guess that even English speakers must sometimes say "electric tension" instead of "voltage". In the ...

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This diagram (cribbed from here) shows the voltage current curve for a typical zener diode: Below the breakdown voltage the diode does not behave as a perfect insulator, but has a small leakage current. This means the voltage across the diode is strongly current dependant. The minimum current, $I_{Z(mini)}$, is simply the current at which the breakdown is ...

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Two points: the drift velocity is the average velocity of electrons. The actual speed of electrons in a metal is quite large, however they go in every direction so the current is zero in the absence of an applied field. An applied electric field will cause slightly more electrons to go one way than the other resulting in a small average drift velocity. The ...

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There are actually several different things going on. The reason you hear a single tone is because of resonance. The reason that it is usually a higher frequency tone has to do partly with the falloff in amplification with distance and partly (perhaps mainly) with the frequency response of the microphone/amplifier/loudspeaker. Let's model the situation ...

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I believe that the authors, of the reference you provided, explain the reason behind introducing these so-called quasi-Fermi levels at the end of section 4.3.3. For simplicity, let me just repeat it here; perhaps explaining it in different words, with a little more elaboration, would help. I’m sure you're aware of the fact that in $n$- ($p$-) doped ...

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After reading the wikipedia page and this article, I understand your question a little better. A CMOS sensor detects colors by letting light pass through three layers of detector, each with a certain spectral response and absorption. I don't think that each layer is specifically red, blue, and green, rather that their responses overlap and that the processor ...

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if there was no central tapping, what would be the change? Consider this circuit diagram, from the answer you're not satisfied with: There is no "central tapping" so the two diodes are connected in series. In a series connected circuit, the current through each circuit element is identical. Now, note that D1 allows only a clockwise current while D2 ...

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Reverse Bias of P-N junction When the voltage is applied this way round it tends to pull the free electrons and holes apart, and increases the height of the energy barrier between the two sides of the diode. As a result it is almost impossible for any electrons or holes to cross the depletion zone and the diode current produced is virtually zero. A few lucky ...

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I do believe that yes. The most hard part will be to obtain the materials. If you manage to get a good piece of n-type (or p-type) Silicon, big enough to allow you to work with home tools, you'll "just" have to do local oxidation (with temperature for example) and make some soldering. Of course, the quality of that transistor would be very doubtful as it ...

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Since you mention batteries in a comment: The voltage source + resistance model works well in many circumstances. At the extremes: high frequency / fast rise time waveforms: There will always be some inductance, from wiring if nothing else, which appears as an inductance, an easy add to the model. low frequency / long durations: As the battery ...

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There are actually two slightly different versions of Thevenin's theorem. I think what you are describing is the weaker of the two: you can replace any circuit with a single voltage/current source and a single resistor. That version holds for any two-terminal network made up only of voltage/current sources and ohmic resistors. It fails as soon as you add ...

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Conductivity of intrinsic semiconductor is due to their own internal charge carriers. The bonding between between two electrons of two neighboring atoms is covalent, therefor at NTP, there is no free charge carrier for conduction. When it is heated, some covalent bonds break due to heat and thus some electron get free for conduction. As soon as one electron ...

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Let's start with the idea of a voltage divider. Connect two resistors in series, and apply an input voltage across the two of them. Then take the point between the two resistors as your output voltage. That output voltage will be less than your input voltage; the two resistors have divided the input voltage into two parts, each part proportional to the ...

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Usually, the Bulk of an NMOS is connected to the lowest voltage in the circuit, for an NMOS and the highest voltage in the circuit, for a PMOS. Then, depending on the value of this voltage and the Source-to-Bulk voltage of this transistor, a Threshold Voltage is defined, which is also called Turn On Voltage in some cases(especially in the digital circuits). ...

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In avalanche breakdown the zener diode does not behave like a pure conductor. It behaves like a "something that consumes N volts" followed by a perfect conductor. An intuitive way to think of it is: it costs you N volts worth of energy to keep the diode in breakdown. If you apply less than N volts breakdown stops and it barely conducts at all (it becomes ...

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Well, seems that Intel can often find some material to get closer to the physical limit. But the limit can't be reached, your transistor needs at least 1 atom. Another limit is on the clock frequency, which is essentially due to material's intrinsic property (mobility, or speed of electrons). Graphene may have a good chance for its ultrahigh mobility. One ...

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