Transistor Definition and 508 Threads

What happens if a NPN transistor's collector voltage is below its emitter voltage? Say we have a NPN transistor, and the base voltage is at 5V, the emitter voltage is 2V, and the collector voltage is at ground. Will current flow from the emitter to the collector, or is there an internal...

I have a string of leds hooked up together with the correct resistors in parallel, going out to a TIP31 transistor which then goes to the power cord and to a 3mm jack. This 3mm jack goes into my computer and my leds "dance" to the music, I assume is the change in voltage. Anyways, I have...

transistor problem, helpp! [PLAIN]https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc6/270474_2182563849439_1407242959_2536426_5250645_n.jpg how to answerr? thanks

Hey guys, I just found out about these darlington transistors, and I read that the purpose of these transistors are to "amplify WEAK signals". After taking a look at the circuit diagram for the darlington pairs, it seems to me that it is just 2 npn bjts with one of the bjt's emitter...

Transistor "not gate" function I've been trying to understand the following circuit: I'm new to circuitry and electrical engineering, so I've had some trouble understanding the function of transistor Q3 and diode D2, I believe the circuit should function without them. If anybody could...

I have a quick question. I can't find anywhere the answer in my textbook. What is this -Vee in attached image? And how do you equivalent that? And it says here in given parameters that -Vee=-12 V, isn't that +12 V?

Homework Statement Hello everybody,i am new member and i hope that you can help me out in understanding the attached circuit.our lecturer gave us this circuit and asked us to do literature research and try to understand how the circuit work (the parallel port,the transistor circuits,the...

If the base current of an NPN transistor is increased, what will happen to its Collector current since I still don't understand how a transistor amplifies signals or about the current gain. (i.e. Ic/Ib)

Hi All, I'm trying to understand how transistor works. I have drew some pictures for NPN transistor to show my current understanding. Can you please verify this for me. On the picture: "-" and "+" are movable charges; circled "-" and circled "+" are immovable ions. 1. No voltage applied. Two...

I am looking to design a circuit, most likely with a transistor, to act as a voltage controlled rheostat. The controlling voltage can range from 0 - 3.3 v and I am trying to get a resistance range of about 200 - 5500 ohms. The circuit should have fairly high input impedance since it will be...

I am trying to understand transistors. Here is what I got. Assume we have a forward biased transistor(emitter-base direct, collector-base inverse). The point of transistor, in this mode, is to amplify a signal from base. That signal will vary the current in collector. So if i have a AC...

I want to implement the following very simple logic: Voltage at point "A" is high ==> LED is OFF Voltage at point "A" is low or floating ==> LED is ON and I came up with the attached circuit to implement it. I'm just wondering if there is anything "bad" about doing it this way, or if...

I want to ask a fairly simple question. Its about transistor working modes. Just to be sure I am thinking right. If we apply positive voltages to both EB junction and CB junction. By that I mean that Positive potential comes to collector and positive potential comes to emitter. I've learned...

Hello everyone, :smile: I am trying to understand how a transistor works. Let's start with a NPN transistor. I read somewhere that NPN is just two diodes joined by sandwiching their 'P' regions between the 'N' regions. In other words by joining their anodes together. Please have a see on...

I need some kind of four pin transistor that is neither common drain nor common source. Both positives and grounds need to isolated. Does that exist?

Hi, I am new here and I need some help on a massive project that has a large bearing on our end of year results. Its got to do with clipping of an output signal in a common emmitter BJT n-p-n Voltage Amplifier circuit. It asks us to comment on the clipping and relate it to Vs and Vc. Where Vs is...

Hello Experts, My darlington pair cannot amplify the signal to the desired level. To further amplify, is it as simple as adding another transistor (all NPN) where the Emitter of the second transistor is fed into the base of the 3rd transistor and this 3rd transistor collector is shorted to...

Homework Statement What region of operation is this NMOS in with a negative Vds? Kn=250μA/V2 and VTN=1V d) VGS= 1.5V and VDS= 0.5V e) VGS= 2V and VDS= -0.5V f) VGS= 3V and VDS= -6V Homework Equations (vgs -Vtn)≥ vds ≥ 0 -- Triode vds ≥ (vgs - Vtn)≥ 0 -- Saturation The Attempt...

Homework Statement Calculate the output impedance of the emitter-follower circuit called a pass transistor. Assume that beta=200 **See attached diagram** Homework Equations The Attempt at a Solution Not really sure how this works, I thought it would just be 1k cause that is the...

Hi, Working on a project, I am told to find the K,n value of a specific transistor (2n7000), given the spec. sheet. I know K,n can be found from the formula: I,d = K,n * (V,gs - V,tn)^2 I'm close, from the spec sheet, I can use a V,gs value and a corresponding I,d value, however not sure what...

This is for a 300 level electronics lab class and I'm wondering if I'm close: Homework Statement If the following silicon transistor (VBE = 0.6 V) has a B value of 100, determine IC and VCE. Homework Equations http://img862.imageshack.us/img862/80/circuit1.th.jpg Uploaded with...

Greetings, I had an argument with my substitute Physics teacher about the use of the transistor and how important it is/was. Basically, we were debating whether or not it is important because of the invention or whether it was purely the concept that made it so important. His argument was...

just wondering, what is the difference between Base-Emitter Saturation Voltage and Base-Emitter on Voltage ? VBE (sat) = 0.5V VBE (on) = 0.7V

All electron flow nuances aside, let's look at simple circuit analysis. Hopefully you guys can clarify something for me. Say we have to drive an LED. We have a +5V source, a 3.4V forward voltage, and a 150 Ohm current limiting resistor: +5V --> Resistor --> LED --> GND Okay, so let's...

Homework Statement The absolute max voltage rating for the base-emitter voltage is the lowest of all values. This low value means the B-E junction must be protected from a high reverse voltage. A diode is used for an npn transistor. Explain its function and conditions under which...

Is there a limit to how long a transistor, like in a cpu, can be constantly on?

I'm planning to design a PIR motion sensor. I wanted to know if I can use ordinary class-A amplifiers to amplify the output of the sensor which will be given to the alarm circuit. The transistor I'm planning to use is BC-547

The ouput of common emitter transistor 1 is connected to input of common emitter transistor 2. Please explain about the input and ouput signal (ac). 1.Is there any amplification after the transistor 1? Normally the input is in uA, the output is in miliA 2.Is there any amplification after...

Homework Statement Determine transistor sizes for (lets say a 2 input nand gate, my actual question is more complicated but i want to know the basic idea so i can do it myself) so that the worst case pull down and pull up is equivalent to a single inverter with Wn = 1 micro m and Wp= 2 Micro...

Hi I'm practising past papers however have no answers. one of the questions says: Why can a p-n junction connected in series with an n-p junction not act as an p-n-p transistor. My only thoughts were that the base element must be thin (approx 10 wavelengths of light) and in thus in this...

this circuit http://www.edutek.ltd.uk/Binaries/Prj%20Roulette/Roulette%20wheel%202.pdf needs a BC183L transistor...sadly this is a European transistor and I need an American crossover/equivalent... can anyone tell me what transistor is the EXACT crossover...or a transistor that would...

Hello, I have two devices, one that emits a 5V DO and another that receives a 24V DI. I wanting to interface them but am having problems. I was searching for a small solid state device that could easily interface them but could not find any. So I have been trying to creat a circuit using...

I am trying to drive a NPN transistor with a LM324 op amp. The darn transistor does not turn on when driven by an op amp. This is basically a current limit circuit. Instead of using a large value sense resistor, I used a small resistor(0.1 ohm) and used an op amp to sense and increase the...

When do you use an internal substrate connection vs an external substrate connection on a depletion mode transistor?

1. Homework Statement [/b] calculate alpha DC (emitter to collector dc current gain) and beta DC (base to collector dc current gain) for a transistor which has Ic=2.5ma, Ie=2.6ma . Homework Equations formula 1) alpha DC=Ic/Ie. formula 2) beta DC =Ic/Ib. formula 3) beta DC = alpha...

Hi everyone, I'm currently working on a project and part of this project may need transistor circuits in it. As I'm totally new to transistors and circuits I would greatly appreciate any help offered. I was wondering if it is possible to program/create transistors to perform certain tasks...

I've got a bunch of misc. transistors from various sources and I'm not sure what types they are. Is there an easy way to generally determine how a transistor is configured or do I have to find a data sheet each time? It's been a long time since I did anything with electronics. From what I've...

Hi guys, I am trying to find a way to calculate biasing network for the attached circuit. Basically I need to find R1 and R2 values for operating point of I0 = 10mA and V0 = 10V and Vs = 16V. DC current gain is assumed to be hFE=80. How do you calculate R1 and R2 based on these info...

i wonder if anyone could tell me ,why does the current gain change as the frequency of ac supply changes? advanced thanks.

greetings, when a transistor in common emitter configuration is given a ac signal with base current,the amplified output form from collector of it gives inverted polarity of the input voltage or the output graph of voltage versus time gets inverted of input graph of voltage versus time.how is...

can anyone tell me what is pass band voltage?what do we meant by cut off frequency of a transistor? advanced thanks.

greetings- suppose a transistor connected with emitter and collector resistor. when this transistor is given a AC signal, will the current through the emitter and collector resistor will vary as input AC signal varies? variation in AC signal in the sense the direction of flow of current...

What are the effects of "Analyte-Nanotube interactions" in the CNTFET device?

Hi folks, I am desperately trying to understand how this device is working... I would like to precise that I understand how field effect transistors/junctions based on p- and n-types semi-conductors are working (with a p-type gate it is ok; with a n-type gate it is already less ok since holes...

Homework Statement See attachment. Homework Equations The Attempt at a Solution Input resistance is R1||R2 I don't know how to calculate output resistance. To calculate the base current, I calculated the voltage at the resistor divider (5V), thevinized the base circuit and...

can anyone please tell me when and why we required different configuration of transistor i.e. common emitter or common base or common collector? advanced thanks.

how can i know the current gain of transistor fom its data sheet?? when i open a datasheet for a certain transistor i find a relation between Ic and Hfe at a certain Vce (ex Vce=4 volt), did this relation only correct at that Vce ? and if its that how can i calculate the Hfe for a certain Ic at...

i was try to built a simple transistor circut , i chose Ic=0.5 mA , i used s8050 transistor , by looking at its datasheet i found that i ve to make Vbe=0.56 V and Vce= 1 V in order to obtain Ic=0.5mA.i used power supply with output 12 volt and max current 9 A . by using 2 plots 10k and 200k i...

Homework Statement On one of the homework problems on NPN type transistor, I am asked to find Beta. What does Beta mean? Is it amplification? Is there equation for it? Homework Equations I'm looking for an equation The Attempt at a Solution

would you please tell me,in common emitter transistor configuration what is the use of grounding the emitter? thanks