Transistor Definition and 508 Threads

http://www.slideshare.net/viv3ksharma/automatic-school-bell In this circuit I Think the emitter and collector terminal of the transistors T1 & T2 will be reverse. Otherwise the 555 timer will not discharge. Can anyone help pls?

In an automatic school bell circuit, The outputs from 3 to 11 are connected to the base of an NPN (BC547) transistor through 1K resistance. A diode is connected in forward bias in each of those outputs so that only one output sends high pulse to the base of the transistor. When the high pulse is...

i had a thought to stick two diodes together such that the electronic setup was similar to that of a BJT transistor. however i have been told by multiple teachers/professors that the two were not equivalent. I have drawn a picture to show you what i mean. the top two pictures are just the...

http://www.digikey.com/product-search/en?WT.z_header=search_go&lang=en&site=us&keywords=MOSFET+N-CH+250V+10A+TO-220FM&x=0&y=0 I just recently bought this N-channel MOSFET transistor and when I hook the first pin (gate) to 5V, the second pin (drain) is just an open wire, and the third pin...

Hey all, So I took apart an old computer monitor to try and harvest some of the hardware inside so I don't have to buy all that stuff for my hobbying, and I was wondering if it is possible to measure the specs on the transistors inside without having to put them into a circuit and see how...

Can you help me check my work and tell me what is the application of the circuit? Homework Statement Sketch Vout versus Vin as Vin varies from 0 to VDD. Identify important points. Homework Equations MOS transistor equations in triode and saturation modes. The Attempt at a Solution

Here is an image show how currents flow in NPN transistor from Microelectronic Circuits by Sedra Smith: Can you explain more about injected holes (iB1)? I can't imagine how holes can flow into emitter (N type) Is it possible to for holes to flow from base to emitter?

Hi, this is not a homework. I need your help to understand basic concepts. I am learning by myself. In textbooks, I usually see the circuit used to make Ic -Vce characteristics. I see that there are no resistors at base and collector/emitter. What will happen if VBE is larger than 1V or...

Homework Statement Find the base current of the following circuit Homework Equations The Attempt at a Solution The solution to the problem is 4 micro amperes. Why? I get base current = 0 A because the transistor is satured and colector current=emissor current=1 mA

Homework Statement Problem number 6a in the picture. Homework Equations Transistor: Ic = βIb Ic = αIe Ic = Is*e^(Vbe/nVt) OP-Amp: Vo = Acl*Vi Acl = 1 + (Rf/Ri) The Attempt at a Solution I tried to solve but just couldn't understand the behavior the transistor.

I have not any clear idea about the saturation region of a transistor. Can anyone help me in detail? What parameter actually becomes saturated in this region? Why are both the junctions becomes forward biased? Is it possible to widen this region for a particular transistor?

Homework Statement THe problem statement and given solutions are in this thread: https://www.physicsforums.com/showthread.php?t=694054 I do not understand the equation for current gain: Homework Equations Ai = \alpha\frac{R4}{R4 + Ri} The Attempt at a Solution I have pages of...

Homework Statement consider the following circuit: a) Determine the value of the resistor, R so that a current of 0.5 A flows through the load. b) What is the maximum value of th load resistor? c) If the load resistor is 10Ω, what value of VB will put the transistor into saturation? Homework...

For question 1, it asks me to find the operating point by different methods. But I have no idea to solve it. Can anyone give some hints for me? I can just think about the diode can be replaced by an ideal diode, a 0.5V dc source and a 0.2/4=0.05Ω resistor. For question 3, I have solved...

Homework Statement I seem to have no problem applying KVL to NPN transistor bias circuits, but a world of trouble getting my polarities straight on PNP transistor bias circuits. The +'s and -'s are driving me crazy. :rolleyes: The following circuit was presented in the "Voltage-Divider...

Homework Statement Hi there. I was just wondering if anyone can conform that my method for this problem is correct so far? The transistor-bridge converter shown below is being used to connect a PV array to the grid. For the purpose of this coursework, you may assume that: • The PV array...

Homework Statement I am looking for the base, collector, and emitter voltages in the following circuit: Homework Equations KCL KVL offset voltage = VB - VE saturation voltage = VC - VE The Attempt at a Solution First I made a matrix without assuming any values for offset or...

I have a few questions about offset voltage for a bipolar transistor... A. Why is this value not specified on datasheets? My EE book says it is usually between 0.6 and 0.7 for silicon, and provides its exact value in textbook problems. Besides experimental measurement, how could I know...

So... My transistor does the switching job when I put my finger on its base. I know that NPN transistor are activated with positive charge, so... What happens between transistor, my finger and the earth? What happens to the charge? I don't know much about this, I would like an introduction...

http://www.dummies.com/how-to/content/electronics-projects-how-to-create-a-transistor-na.html In the above link it is said that the output is logic ON if both the inputs are OFF. What does that mean. Correct me if I am wrong. As far as I have learned from the site was when the input is ON...

Hi, I'm working with a microcontroller that outputs 5V, 25mA max from each pin. I need to source 120-150mA. I'm looking at 2n7000 MOSFET for the job. Spice simulations show the output current is 50mA when Vg = 5V (microcontroller output) and about 120mA when Vg = 5.5V. Since I'll be using over...

I just wanted to see if I am understanding this circuit correctly. Let's say the input voltage (V_in) is 0. This means: 1) no current through the 1000 ohm resistor 2) no 0.7V drop from the base to emitter 3) transistor is pretty much off 4) The circuit is open, thus no current goes through...

How does a transistor work as a switch and amplifier?? i know a transistor is a device that controls the flow of current but how does it act as a switch and an amplifier? i tried reading about it on so many places but i just can't seem to get it :confused: ...the diagrams just don't make sense...

Homework Statement http://web.stagram.com/p/362176186041336029_243276631 this is a link to the question. I'm stuck on 2a and b Homework Equations I don't understand if the voltmeter is reading 6v why the light is not receiving 6v? And why would a transistor help this problem? The...

The load line of transistor depends on resistor of base or resistor of collector ? Or both? thank

Hello. I've a question about transistor IRF-740. This component has a Zener diode connected between drain and source. Has this diode a function of limiting over voltage ?

So I am working on a project and I am using a diagram I found on this forum but I want to alter it a little. The transistor on the right is a 2n2222 npn transistor. I want to change the 9v to 24v. I've been looking up datasheets on it and I think it will do what I want but I wanted to get a...

Im new here and I am currently working on a small IR encoder project. I have the encoder working great but now I need to use the 5vdc signal that comes from the encoder and make it 24vdc. I am currently trying to use a bipolar transistor but its not working. The basic diagram that I am going off...

Hello, I am trying to design a circuit that can measure the BETA of a PNP and NPN transistor, I have an ammeter, and I have a design that makes IB going in 0.1mA, so that the current IC of the collector with a shifted decimal is the Beta we would like to measure. So I used a current source, and...

Homework Statement I’m having trouble with analysing the transistor circuit attached to find VC, VB, VE, IC, IB and IE. Homework Equations These equations are taken from a previous example VE = VBB – VBE IE = (VBB – VBE)/RE IB = IE/β+1 IC = β/(β+1) x IE VC = VCC – ICRC β=100...

For a npn transistor, Vb= +0.7V ,Vc=+1.0V , Ve=0 Then my teacher says it is not operating, why is that so? Thank you.

In order to draw the load line of transistor, we have to find out the saturation current (where the voltage is minimum or zero) and voltage of collector-base when collector current is zero. In order to calculate maximum saturation current, we have to forward biased the base-emitter, and...

Homework Statement I have to solve for RD, RS1, and RS2. Homework Equations AVNL=-mg(Rd//rd) Vdd-Id(Rd+RStotal)=0 Bias Line Eq: Vg-Vgsq-Idq(RStotal) The Attempt at a Solution I have solved for RD by using the AVNL equation and the given value of -8 for AVNL. I found RD to be...

can somebody teach mm how to find desired voltage gain of ce a transistor amplifier which is formula, i know the formula is rc:rl/re but i want for example a voltage gain of 50 for example input desired data: desired voltage gain 2.0 which i want to know f_min = 10 HZ z_in = 50 K...

Let's consider npn transistor, when emitter-base is forward with voltage supplied to it, then the majority charge carrier(electron) will diffuse to base(p-type) , Then (in base-emitter) the minority charge carrier in p-type (electron) will that move close to the depletion layer of...

Homework Statement Ok so I have been given a diagram which if it worked should be attached. I am having a fair bit of trouble understanding it. Now I am aware that there is both electrical and conventional currents but I am confused as to whether this is electrical or conventional. I have been...

Homework Statement I am given a problem for my electronics class that asks to design a transistor switch that will switch a 10-Ohm load powered from a +5V supply. The transistor beta is about 50. It also asks which current is needed to turn the transistor fully on (saturate it so that the...

when transistor is operated in SATURATED REGION , then for npn transistor BC junction becomes forward biased and holes will move from base to the collector, so more holes should be provided by the battery to the base terminal. So if this is the case then base current should increase . But when...

A transistor need both adequate current and voltage to be activated right? And does it get damaged by connecting in wrong terminal?

Homework Statement http://img846.imageshack.us/img846/955/29278644.jpg The Attempt at a Solution Basically I want to know whether my working method was correct as I have doubts with some of it. I first did voltage division at the two base resistances, and I get 3V at the base. Since we know...

A couple questions: I'm in the process of making some small amplifiers and using bjt's in the small signal realm. I have used bjt's as switches for quite a while, so I am quite familiar with their basic operation. I was reviewing small signal analysis trying to refresh my memory about how...

Hello, I am trying to derive the harmonic content of a signal passing through a transistor's transfer function. After a Taylor expansion in Mathematica 7, I have the expanded equation and the next step is to reduce everything to first order Sine/Cosine functions. In Mathematica, if I have a...

Am doing a project that has to use a transistor, as a switch, actually switching a 12V relay switch, that is actually responsible for switching another circuit, but as a result the relay doesn't switch ON, but makes noise continuously, in this clearly certain that the voltage across the relay is...

I succesfully did this example from my book without checking the solution, but I came up with a question that I cannot answer on my own. What would happen if Re was set lower? The base is grounded and Vbe is independant of the current Ie, so by choosing a resistance smaller than 7070ohm for...

Hi there! I'm having trouble understanding the transistor circuit analysis. Hope you could help me :) First I need to find the active region of the transistor. What I saw in the solutions was an assumption that the transistor is in saturation region and then: VBB=IbRb+Vbe+IeRe...

I have a battery operated digital timer circuit board that will control a small motor, via a control board. The timer runs on 3.6vdc (batteries). The timers Output Control Signal is 3.6vdc when on, and 0Vdc when off. The timer is replacing an old analogue timer. The old timer had normally...

Homework Statement If a transistor circuit is used to amplify a 2.5 mA signal to at least 0.1 A, what must be the minimum gain of the transistor circuit? b. Assume the amplifier consists of a number of transistors in series, each with a gain of 10. How many transistors are needed in...

The formulas in question are: Beta = Ic/Ib Ie = Ib ( 1 + beta ) Ie = Ib + Ic

Hi everyone, took a bit of a break lately...but with 6 days left to the final test of electronics, I figured I'd clear up some understandings I have Homework Statement http://img225.imageshack.us/img225/4474/vbbreversed.jpg I'm asked if the VBB potentials are flipped, at what condition will...

hi i have an exam next sunday and i really have no clue about this thing.. in an transitor IC-Vce graph(as it apear on the third page of this site - (first line and right graph) www.onsemi.com/pub_link/Collateral/2SB1204-D.PDF) why are the Vce and Ic changing when the Ib is staying the same?