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Questions tagged [emitter]

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-2
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0answers
45 views

Common Emitter Amplifier wrong chart

I'm going to be honest with you guys. I'm totally green when it comes to electronic, but I need to pass labs (as you do). I was given scheme of what I think (I did some digging) of is Common Emitter ...
0
votes
0answers
34 views

Drive 433Mhz emitter and Attiny with two coin cells

I would like to detect when the postman put mail in my box, so I was thinking about a simple attiny with tilt sensor (which would wake up the attiny) and a 433 MHz emitter: The problem is that one ...
1
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1answer
55 views

40 kHz Emitter Frequency Response

I've recently purchased 40 kHz transceivers and I tested its frequency response in anechoic chamber using a B&K microphone located 90cm away from the emitter. The response provided in the ...
0
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2answers
31 views

Does Differential Amplifier Emitter behave as ground in AC-analysis?

I am trying to solve various differential-amplifier homework problems for which I have the solution to study. For the simplicity of most problems we are able to neglect base-currents. Moreover, it ...
-1
votes
3answers
121 views

Are IR emitter frequencies adjustable? Can modulation of the emitter variate material absorption properties?

A common LED emitter, Gallium Arsenide, apparently has a wavelength of about 760 nm. Then on the receiving end, there is a filtering circuit to eliminate ambient IR and to demodulate the message. Can ...
0
votes
2answers
1k views
1
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3answers
181 views

AC Analysis of emitter circuit, why can I ignore resistance R1 but not Rc?

I am trying to calculate the small signal voltage gain of this circuit but I am having a problem comprehending the last step. I rewrote the circuit like this But the solution says this: Which would ...
0
votes
1answer
703 views

How to calculate the collector resistor of this emitter circuit?

My supply voltage is +10 V, collector current at my bias point is 5 mA, base current is 28.8 uA, amplification is 173.3 I already calculated the base resistor to \$R_1=\frac{V_{CC}-V_{BE}}{I_b}\$ and ...
0
votes
2answers
184 views

Collector must be more positive than the emitter

My book (The Art of Electronics by Paul Horowitz and Winfield Hill) is stating something that seems to be the opposite of the example it is using. I am not going to school for my studies so I ...
1
vote
1answer
745 views

Are there any SOT-23 BJT's with swapped Base and Emitter pins? [closed]

The standard NPN BJT in SOT-23 package has the following arrangement of pins: Do you know of any transistor that has pins 1 and 2 reversed? So that 2 is the base while 1 is the emitter (Doesn't ...
2
votes
5answers
2k views

Finding the Base-Emitter Voltage in an NPN Transistor

The problem asks to find the the real value of base-emitter voltage, \$V_{BE}\$ and the corresponding \$I_C\$, and \$V_{OUT}\$ in the figure below: \$V_{CE(sat)}\$ is given but the transistor is not ...
-3
votes
1answer
67 views

Are there methods to stabilizing \$V_{BE}\$ [closed]

For \$V_{IN}\$ >> \$V_{BE}\$ (\$V_{IN}\$ in reference to GND), the \$V_{BE}\$ is quite stable typically only varying in 8mV for silicon NPNs and gets smaller when the emitter is conducting less ...
1
vote
4answers
266 views

Finding the Real \$V_{BE}\$

In a BJT in common emitter configuration, what formula can you use to calculate the real \$V_{BE}\$ so that you don't have to approximate it as \$0.7V\$? The problem below asks for the actual value of ...
1
vote
1answer
177 views

NPN transistor energy drain from base to emitter?

I have the following example circuit: I do not understand why this lights the LED. For my main project I am building a circuit that has a button connected to an output as well as the collector of the ...
0
votes
1answer
2k views

What are the reasons that the emitter is heavily doped in an NPN BJT? [duplicate]

Is doping the emitter more than the collector crucial? Would current not flow at all if both regions were equally doped? Why? Is there a way to explain this in a simple fashion?
1
vote
3answers
216 views

Why are these resistors considered in parallel in the DC equivalent (Com Emitter Amp)

So here is a page from my text book, the Common Emitter Circuit is on the top and on the bottom right you can see the DC equivalent circuit , my question is that by looking at that dc circuit i do not ...
0
votes
3answers
483 views

Finding the operating point of a transistor circuit

I want to find the operating point of this circuit: where we have a npn-Transistor and \$R_V = 47k\Omega\$, \$R_C = 1k\Omega\$, \$R_E = 4,7k\Omega\$, \$\beta = 100 \$, \$+U_B = 10V\$ and \$-U_B = -...
0
votes
1answer
271 views

IR emitter LED with jack 3.5

Currently I'm using an IR LED connected directly to a PCB where an Arduino UNO is connected. When I send a command with the Arduino, the LED sends what I want to an IR receiver. Now I'm thinking to ...
0
votes
1answer
73 views

Calculate the parallel value of resistors at base of common emitter amplifier

I don't know if questions can be asked like this here but if they can I want this question. In an exam paper I saw a question to determine the parallel value of the R1 and R2 resistors in the image ...
0
votes
1answer
145 views

Pspice Common Emitter Schematic Missing Values

I am doing some homework for universiy and PSpice keeps saying that there is some missing values.I cant seem to find a solution in my books so I though that i might share my issue with you and ...
1
vote
4answers
2k views

A question on voltage divider resistances used in BJT biasing

I'm reading a text on BJT common collector amplifier biasing. Text says: The voltage divider (R1 and R2) is used to give the input signal (after passing through the capacitor) a positive dc level ...
3
votes
3answers
979 views

Confusion on the meaning of a BJT emitter follower's output impedance

Above figure is a BJT transistor emitter follower. I can understand that in an emitter follower when talking about its input impedance what meant is Vb/Ib and here it is equal to (hfe+1)*R. The idea ...