Transistor Definition and 508 Threads

  1. D

    Solve Two Tasks with One DC Signal: Solid State Switch Circuit

    My goal is to use a single signal to do two things at the same time...when DC signal is applied turn transistor1 off and turn transistor2 on. Then when signal is not applied transistor1 returns to on and transistor2 returns to off. Frequency will be no more than 60Hz. What would this circuit...
  2. R

    Deciding Miller Index when building a transistor?

    In obtaining the materials to build a transistor, should one choose wafers of the same Miller indexes? Will the lattice structure affect the interaction between two wafers?
  3. S

    How BJT transistor works (with conventional current notation perspective)

    So far the explanation on BJT working principle always explained in electron flow perspective. I felt it's hard to relate with conventional current direction notation when the explanation explained in electron flow direction notation. For example in NPN transistor, the C-E current flow made me...
  4. M

    How to Design a Simple Transistor Amplifier with Given Data?

    Homework Statement The circuit above shows a simple transistor amplifier with the given data: β=100, VA = 100V, RL = 10kΩ a) neglect the "early-effect" and design the circuit so that IE = 0.5mA and VC = 5V. Homework EquationsThe Attempt at a Solution I'm familiar with the β part, it means...
  5. R

    Carrier flow in BJT when saturated

    I would like to know how carriers flow in a bipolar junction transistor when working in saturation mode. Normally, electrons would flow from the emitter to the base. Then, from the base, some recombine with holes nad leave, forming the base current, and the others (the majority) diffuse in the...
  6. S

    "Switching Transistor" OFF Impedance

    Hey all, When a Bipolar Junction Transistor is "OFF" (i.e., Vb = 0), what are typical Emitter-Collector impedances? We are using a switching BJT as a switch for a stepper motor, however, we have just realized that the impedance is rather low when the transistor is off (470 Ohms). I would have...
  7. M

    Clipping in a transistor amplifier

    I need to understand how does an amplified signal gets clipped depending upon the biasing voltage level? It says that upon insufficient biasing, the output voltage becomes constant, but how? Please if you attach this link:- http://www.electronics-tutorials.ws/amplifier/amp_4.html I mention you...
  8. A

    Why can't I saturate this transistor?

    Hi, I started using Proteus Isis and was playing around just to get used to it. I designed a simple transistor circuit that should work in the saturated region. The LED needs 2.3V. For saturation, the collector and emitter terminals should be shorted or have a tiny voltage drop across it. So...
  9. T

    How Does Each Component Function in a Transistor Intercom Circuit?

    Attached with this post is a picture of an intercom circuit using only transistors. It is a two-staged coupled amplifier circuit. I have constructed this circuit for my college physics project. But for the report I want to know the functionality of every component of the circuit. I would be...
  10. S

    NPN transistor model for use with differential equations-LC oscillator

    Hello, I am trying to get a better understanding of how oscillator circuits (clapp, hartley, colpitts etc) work, so I have been trying to solve the differential equation for a very simple one--the one most the way down the page here...
  11. ranju

    Transistor Biasing: Zero Signal Collector Current Explained

    I have studied that "zero signal collector current should be atleast equal to the maximum collector current..." but what is the reason behind this?? and why we need to to consider this zero signal collector current .ultimately what is the significance..if we have to see when we apply the signal...
  12. K

    About output characterstics of a npn transistor in CE configuration

    Q1.when transistor[NPN transistor in CE configuration] is in saturated state ,then,in output characteristic curve on increasing voltage across collector -emitter,the current in the output circuit increases linearly but my confusion is that we know that in saturation state transistor's base...
  13. 462chevelle

    Transistor as Relay Setup: Tips for Quicker Circuit Release

    I'm looking for some help setting up a circuit system. Were currently using a magnetic type trigger relay. I am trying to get a quicker release of the circuit. Its for the trans brakes on our drag cars. Here is what i was thinking, this is of course a very rough and first draft of my thoughts...
  14. C

    Solving Transistor in Cutoff: Vtp=-0.4V

    Homework Statement The threshold voltage (Vtp) of this p-channel transistor is -0.4V. Determine the region of operation of this transistor. Homework Equations Vsg + Vtp = Vsd(sat) The Attempt at a Solution Since the gate-source voltage is 0V, and the threshold voltage is...
  15. Salvador

    How Does a Transistor Output Multiple Frequencies Simultaneously?

    Good day , Transistor characteristics tend to change under load and at various frequencies and teperatures etc, but when we have a simple linear class ab amplifier with two bjt output devices , I wonder how does a single transistor output various frequencies at once? I understand it's...
  16. S

    Solving Transistor KFY34 Switching Load Homework

    Hello, I've spend a lot of time at following example of my homework but still unable to find a solution. In fact I have no idea how to solve that, any help would be very appreciate. Homework Statement Transistor KFY34 has to switch a load of nominal supply voltage 24V and resistance...
  17. S

    Understanding transistor Ptot in data sheet

    Hi, Reffering to the attached image, I wonder how total power dissipation is defined in each case; "Tamb < 25C" and "Tc < 25C" respectively. I suspect that Tc is referring to usage with a heat-sink , but it makes no sense as the TO92 case is not well suited for heat sinks. Thanks in advance!
  18. NoobLala

    Help Me I Dont Really Understand About BJT Transistor

    Hyeee. This Gonna Be My First Post. Really Hope You Guys Can Help Me. I Dont Understand On The Operating Principles Of The Sensor Circuit Shown In Figure (d) and Figure (e) . Can Someone Describe It For Me? I Have Quiz On Thisssss..Arghh. Can BJT Transistor Works As Switch? How...
  19. T

    Engineering Solve for Vo in Transistor Circuit

    Homework Statement So I am supposed to find Vo in this circuit. Given, Vb-Ve=0.7, ic=100ib, ie=ic+ib The Attempt at a Solution In order to solve for Vout i did KVL for the two loops: Loop 1 (left side, clockwise): Vb-Ve-ie(416)+2-ib(10*103)=0 0.7-ic(416)-ib(416)+2-ib(10*103)=0...
  20. ajayguhan

    Base and collector of transistor

    which is light doped in transistor, whether it is base or collector ?
  21. S

    Building an Optical Transistor - Can it Work?

    I was recently looking in lasers and and their uses and while watching Cosmos with Newton using a prism to shows the different colors of light from white light i got thinking. I stumbled onto the top optical or photonic computers a while ago and I decided to look into building one. After...
  22. Alpharup

    Saturation region of transistor

    Let us consider an npn transistor. The emitter is grounded and the transistor is operating in CE mode. Consider that the region of operation is saturation mode. My teacher asks us to consider that Voltage between collector and emitter is 0.2 V, that is, Vce=0.2 V. I have read a few posts in...
  23. O

    Transistor bypass capacitor for specific frequency

    Homework Statement To circumvent the negative feedback needed for thermal stability and to avoid the accompanying reduction of gain, a bypass capacitor CE needs to be placed in parallel with an emitter resistor RE, such as in Fig. 4.14a, cf. Fig. 18a. Determine what capacitor needs to be...
  24. A

    Why Do We Require Transistor Switches?

    why do we require transistor switches ...I read one related forum in that it was written transistor switches can be triggered using electrical signals. TRUE.but if at all u want to off the ckt give zero signal(may be through microproccesor) to the o/p directly why do you want to increase your...
  25. S

    Transistor amplification related doubts

    I understand the basic concept. A small change in the base current will lead to large change in the collector current and will lead to amplification. But the question is, the small change in base current is brought by input signal or the biasing? Also the coupling capacitors allow only the ac...
  26. R

    How Do You Calculate Gain in a Transistor Amplifier Circuit?

    Homework Statement A typical transistor amplifier is shown in the Figure. Find the amplifier gain G. Circuit diagram: http://i.imgur.com/Rzv4JR7.png Vs = 280mV R1 = 100Ω R2 = 7kΩ R3 = 100Ω Vd = 4*10^5 Ib (Ib is current through R3) R4 = 7kΩ R5 = 900Ω Vo = ? (Voltage drop of R5)...
  27. J

    Transistor Circuits Homework: Explaining Circuit Action as VA Changes

    Homework Statement Please see circuit diagram attached which I am struggling to understand. The question is: explain in detail the action of the circuit as VA changes from –5.0V to +5.0V. I have looked through my textbook and I can see that when VA reaches +5V the base of the transistor...
  28. D

    Why Are Electrons Not Attracted to Holes in a MOSFET Without Gate Voltage?

    Homework Statement I currently reading about transistors in a solid state course. And the transistor is a MOFSET, which I have to describe. I can't really find a nice figure of the one I have in my book, so I will just try to explain my confusion. It says that you make a MOFSET by having a...
  29. Z

    Single electron transistor at high-temperature

    From Ck=[{e^(-Scl)*gamma(N+1)*gamma(N+1+u)}/{gamma(1+u)}]/[{gamma(N+1+a-k)*gamma(N+1+b-k)}/{gamma(1+a-k)*gamma(1+b-k)}] How to prove Ck=[e^(-Scl)*{gamma(1+a-k)*gamma(1+b-k)}]/{gamma(1+u)} to get Ck=[{gamma(1+a)*gamma(1+b)}/{gamma^2(1+k)*gamma(1+u)}]*e^(Scl)? by u=[g*Beta*Ec]/[2*(pi)^2]...
  30. M

    How Does a Transistor Function as a Switch in Different Circuit Configurations?

    please can you help, explain me in easy way this circuit http://obrazki.elektroda.pl/2237673700_1387888073.jpg normal must be swith in position A q1 on q2 off q3 on switch in position B q1 off q2 on q3 off
  31. R

    How does this circuit *really* work: 2 transistor metronome

    I have some questions about this metronome (clicker) circuit found in Radio Shack's "Getting Started in Electronics" book. This circuit seems to be a popular one out on the internet(s) as far as metronome circuits go. Circuit: http://imgur.com/XyTasy3 The other night I said to myself...
  32. T

    How to Determine RE for a Sinusoidal LED Current Offset of 27 mA?

    Homework Statement We have a transistor with RB, RE and A LED being a GaAs Light-emitting Diode (LED with a forward voltage of approximately 1.5V. Values for RB= 2K, Vs-offset=5, Vs-amplitude=4, V-frequency= 1KHz, let β=100 what is the value of the emitter resistor for which the LED...
  33. V

    Using a transistor as a (relatively) high speed switch

    So I'd like to pulse a current to a load from a transistor. I can use a µ-controller to trigger a transistor. The µ only has a minimum pulse length of about 100ns or greater. But I would like to have the current flow through the transistor for a much shorter pulse length than 100ns. Maybe a...
  34. ShreyasR

    H parameter analysis of transistor amplifiers.

    In h parameter analysis, we take the input current and output voltage as independent variables. and the Input voltage and output current are dependent on the input current and output voltage. They are related as: Vin = h11Iin + h12Vout ___(1) Iout = h21Iin + h22Vout ___(2) In case of a...
  35. S

    Engineering Selecting a Transistor for Sample and Hold Circuit

    This is my first time here on this forum. I am building an analog to digital converter. It will be running at a frequency of 12MHz and the sample and hold circuit will be 1/8th of that or 1.5MHz. This will be an 8-bit converter and Vdd will be 5 volts. I have a few parts to workout, the sample...
  36. G

    Engineering Electrical Engineering - Circuits - FET Transistor - Voltage Divider

    Homework Statement Find the voltage gain A_{v} http://imageshack.com/a/img692/3117/qkwp.png Homework Equations The Attempt at a Solution Is this the correct small signal equivalent? http://imageshack.com/a/img203/5812/1yfe.png I'm trying to find the output impedance...
  37. R

    How Does a Transistor Work?

    Hey guys, So I built a circuit a little while back using a flyback transformer and a 2n3055 transistor. Basically it just gave me a massive hi voltage output an I saw little inch long plasma arcs. If you guys need a circuit diagram, I can send you the link or just post it here. The main point...
  38. P

    Applying kirchoff's current law on transistor considering it a single

    How can I apply kcl on transistor considering it as a single node since transistor can act as source or sink for electrons due to combination with holes
  39. helofrind

    Transisor beta to design transistor circuit

    i was wanting to know if anyone knows how to choose the value of beta when trying to design a simple transistor circuit? let's say we're using a 2n3904 NPN 12Vcc with with three resistors RC, RB, and RE. how do i determine what value of beta i should use? i want to determine beta so i can add...
  40. K

    How can I properly select and use a transistor for a motion sensing device?

    Hi Everyone, First of all, thanks for such a great resource. I have been lurking for a bit and just made an account to ask for help with a little project I am working on. What I am trying to accomplish is a motion sensing device that performs a function when something enters the detection...
  41. FOIWATER

    Voltage gain independent of transistor?

    My professor asked me to provide a circuit design for a voltage divider biasing circuit whereby the transistor beta is independent of the voltage gain, which he wants to be -100. I maintain this is impossible, as Ic = B*Ib, changing the beta obviously effects the gain. Right? (not...
  42. O

    How Can I Predict Output Current in a Transistor Using Base Current?

    From what I've read about transistors, I thought that I could find the hfe value in the data sheet, then apply a current to base and have the emmitter-collector throughput at a level of base*hfe. It sounded simple, and I was going to have a few different resistors for controlling base current...
  43. D

    Low voltage op amp to control high voltage series pass transistor

    I am in the middle of designing a low drift and low ripple power supply for myself. To control the output voltage, which ranges from 0 to 20V, I am using an op amp whose output is fed into a Darlington pair of power bjts. The output of the Darlington pair is both fed back to the op amp's...
  44. M

    Not another How does a transistor amplify thread

    Not another "How does a transistor amplify" thread I used to think solid state components such as transistors amplified signals. This may be correct, but it most certainly needs elaborating. Transistors themselves do NOT amplify signals. It is my understanding that transistors take an input...
  45. FOIWATER

    Need help biasing this transistor circuit

    I am having troubles biasing this transistor circuit Mainly, I cannot find Ic The only equation I can come up w/ is 6 - Vce - ie*Re - (-6) = 0 but it doesn't help me, as I do not Vce I do not know how to find Ib, Vs is messing me up, I am not sure how to analyze this... The given...
  46. Hyo X

    What is Pinch off in a transistor?

    Suppose I have a channel between a source and a drain in a FET. What is 'pinch-off' and how does it affect my I-V curves? I don't really understand 'space charge' yet. Thanks
  47. T

    Adding a Transistor to Fade LED

    Would it be possible to add a transistor in between the LED and the driver, as shown in the application photos, to PWM and fade the LED with 0-5V logic (Assume the LED has a forward voltage of 3V)...
  48. N

    Engineering Transistor equivalent circuit question

    This is the equivalent circuit to a transistor, I am to find: i )Short-circuit input impedance, H11 ii )Open-circuit reverse voltage gain, H12 iii)Forward current gain, H21 iv)Open-circuit output admittance, H22 Homework Equations Vin = (H11)(Iin) + (H12)(Vout) Iout = (H21)(Iin) +...
  49. M

    Need Help Understanding Transistor Theory: Saturation Region

    I'm self learning electronics and trying to wrap my head around its characteristics. I was looking at this source. Regarding the active and saturation region graph interpretation on that page, I would like to confirm if my thinking is correct. From that graph, it states that the ratio...
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