Questions tagged [transistors]

The transistor is a semiconductor device that can amplify signals and switch power. Most used types are bipolar (BJT, for Bipolar Junction Transistor), UJT (Unijunction transistor) and MOSFET (FET, for Field Effect Transistor)

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73 views

Phase shift near saturation mitigation in input stage amplifier — How does this work, why does this work?

I'm trying to understand how this circuit works on the input stage to the 4192A Impedance Analyzer. Apologies for the quality... this is the best scan I could find. The design is furnished with the ...
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2answers
388 views

Unable to trigger NPN Transistor from 4017 decade counter output

I am trying to make a unipolar stepper motor driver circuit. As a development landmark, I am trying to first run LEDs using the driver. Attached is my circuit. My 555 timer generates regular pulses ...
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1answer
250 views

fixing the amplifier in an old arcade machine

I just joined and need help. I'm trying to fix the amplifier in my Chicago coin speedway arcade machine. It basically works but it has a bad hum in it. I did replace a couple capacitors that were ...
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53 views

Need help in selection of FET for transfer gate

I was studying the variable potentiometer X9C10x series. They are using a series of fixed resistors and some FETs to select points in this series branch. I need one variable point in my circuit. Can ...
3
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2answers
147 views

Help with 144Mhz small signal amplifier not amplifying

I attempted to build a single transistor amplifier to try and increase the voltage signal coming from a Si5351 module, set to 144 Megahertz. My primary goal is to increase the voltage about 3 to 4 ...
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230 views

How does this tone generator circuit work?

I'm an electronics newbie who just started experimenting with the Snap Circuits style kit and I came across this high-frequency oscillator circuit. When I put it together, I hear a middle to high ...
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158 views

What is the use of second transistor in this circuit?

This is probably not a good title, can you suggest me a better one? I have this circuit above, and I am supposed to find its voltage gain \$V_{out}\over V_{in}\$. But I don't understand what use the ...
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100 views

Identifying exact type of transistor

I can not identify the exact model of this transistor. It reacts as a bipolar NPN Si transistor with EBC pin configuration (first image left to right,) not ECB! This seems to be made by Siemens. ...
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73 views

Gain of single input differential amplifier

When performing the small signal analysis of the circuit shown below, with \$ V_{1} = V_{in} \$ and \$ V_{2} = 0 \$, and output taken from \$ V_{02}\$, I consider the small signal model for half of ...
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66 views

Alternate uses for Gate Driver - Driving a Load without External IGBT or FET

What issues would one encounter by using a gate driver IC to directly drive a load instead of using it to drive transistors? For consideration would be the very affordable Infineon 2EDN752x series ...
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178 views

How does the biasing work in a JFET based triangle to sinewave converter?

To those who haven't see this cool little circuit it employs the non-linearity and symmetry of the JEFET to clip a triangular signal to make it more sinusoidal Can someone please explain to me how ...
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269 views

Gate of a transistor and mosfet damaged

In my schematic, I found that the base of transistor Q7 (2n2222) was damaged. I tried to replace it with a BS170 MOSFET, and the same thing happened where the gate was damaged. The microcontroller ...
3
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1answer
206 views

Noise in FET reverse-polarity protection for ADC

I have quite precise ADC circuit. I want to protect input supply voltage (not ADC input) from reverse-polarity using FET transistor as shown on the picture below. I wonder: is there any noise / worse ...
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2k views

Piezo Buzzer Driver Circuit

I haven’t used a buzzer before so I have tried to find out as much I could and finally, I am here to clear my few doubts: Few details about my application: Buzzer: AST1240MLTRQ (i was not allowed to ...
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3answers
100 views

Switch design for shorting the power control pins?

I have been struggling to design this switch for a while and I would appreciate any help. Problem Background: I'm designing a power system for a submersible, using the Mini-box OpenUPS battery ...
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80 views

Beginner trying to resolve transistor issues

I have designed a basic transistor circuit with the EveryCircuit simulator. The idea is that when the switch is open, one LED comes on and when the switch is closed the other LED lights up instead. It ...
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76 views

Reading 2N2222 BJT datasheet

I know this question was asked before, But couldn't understand properly the datasheet reading. I would like to control water pump via ...
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0answers
30 views

How do you find rO when solving this differential amplifier?

gm could be determined using Jacoletto (40*Ic, where Ic was found while solving the bias point)? Some of my attempts at solving the circuit
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51 views

How does this timer 555 and transistor circuit work?

Is this the way this circuit works ? If vref = 5v on the pin #5, then Vthreshold = 5v, and Vtrigger = 2.5v With Vthreshold = 5v, if voltage on pin #6 Vp6 > 5v, then Vp3 is Vo = 0 With Vtrigger = ...
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1answer
150 views

MOSFETs not activating - is this transistor the problem and can it be subbed?

I'm trying to repair a DC motor controller that moves a caravan. The positive side is relay switched, and it turned out that the negative side of the motor supply was switched by a pair of IRF3205 ...
2
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1answer
74 views

How to choose MOSFETS by using the datasheets infos?

I know all the theory behind the MOSFETs, how to calculate the Id current based on (W/L) and (Vgs-Vth) and etc. But, now that I need to project a real solution, I feel like all of this is kinda ...
2
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1answer
51 views

How to control motor (1.5 V at about 0.5 A) with Particle Photon using optocouplers and transistors?

I’m trying to control a motor that runs at 1.5v at ~0.5A using a Particle Photon. I’m powering the Photon over USB (for now, at least) and the motor with a AA battery. I’ve tried designs based off ...
2
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1answer
177 views

Nvidia 1080 ti VRM? SMD Identification

I was hoping that some of you experts could help me identify a SMD on the back of a 1080 ti FE. This item was dropped and it appears has some damage done to it. I would like to replace the missing SMD ...
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46 views

Looking for a consolidated datasheet for commonly used transitors

I found it challenging to look for individual transistor pdf datasheets with somehow different layout styles then extract common parameters. Is there any consolidated datasheet or table that lists the ...
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89 views

Are there errors in the description of this circuit?

Background The circuit describes the operation of a variable voltage power supply. In the description below the circuit diagram there are errors. Read through the description and note down any errors....
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68 views

Does UJT work as amplifier?

I had got a question in job interview " Draw a circuit of common emitter amplifier using Non Bipolar Transistor." As the question said Non Bipolar, so I assumed that it might be related to UJT. But ...
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1answer
87 views

Determining gain, KCL/KWL (Basics)

Below is a pi model schematic of a cascaded amplifier. The goal is to find the gain with Rp as load. So the gain would be: \$ A = \frac{V_{out}}{V_{in}}\$. So i set out to find \$V_{out}\$ in terms ...
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618 views

Simple MM Phono Preamp Design

I'v found myself in need of a new preamp for my turntable (the one built into my power-amp went out with a bang and tripped the breaker!). I'm using a moving magnet type cartridge with output around ...
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0answers
108 views

What causes voltage to increase from 12V to 36V as specified?

Reference article and paragraph: Relays, Selection & Usage (Part 1) - 8 - Latching Relays ...
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422 views

MOSFET input and output capacitances

I need some explanations about the MOSFET parasitic capacitances. Precisely, what I studied is that there are those parasitic capacitances: But generally in digital electronics texts I see that they ...
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79 views

Bipolar transistors that only connect via base to emitter

I am trying to understand how to use this configuration of the LTC2992 power measure IC and the only part I am confused with so far is the two transistors which I have circled. What I know so far ...
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29 views

Modeling redox transistor in SPICE

So i was reading a few papers regarding redox transistors and I would like to model one in spice. However, I don't know how exactly to do it. Looking at this, there is a sample schematic in the ...
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81 views

Calculating the gain of a specific transistor amplifier circuit

NOTE: There is an error in the drawing above — C1 should be connected to the emitter, not the collector. Hi Electronics SE, hope this is the right place to ask this, if not I'll gladly take it ...
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1answer
479 views

Resistor values on a 12v 10a circuit with LT3045 LDO

I am currently working on a project that aims to provide 12v 10a in the final output. I am quite new to EE and wasn't quite sure if I have choose the correct resistors value as highlighted in the ...
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577 views

Comparing sine wave and triangular for spwm using comparator

i am trying to generate sinusoidal PWM by comparing sine and triangular wave. First i just tried to compare sine wave with reference voltage in order to check the working of op-amp. I get a problem ...
2
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1answer
572 views

Simplest way to switch inductive load with arduino?

I'm trying to switch (just on/off) a 3.7V motor (coil resistance 2.2 Ohm) and a 6V motor (coil resistance 8 Ohm) with an arduino mini. And I have trouble finding an universal way to do so. What I ...
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1answer
71 views

What is the least expensive way to build a three-bit shift register?

I'd like to build a queue of three internal bits as inexpensively as possible. Externally, the queue has two input bits and one output bit. The inputs are (dataIn) and (shift), and the output is (...
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261 views

complementary transistor pair npn/pnp in the Kapustinsky circuit

I need to create an old circuit that reproduces fast impulsion, the Kapustinsky circuit (see the picture). This circuit is 33 years old, and a transistor (or equivalent) does not exist anymore, the ...
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3answers
222 views

Behaviour of Voltage on Base in a fixed BIAS Common Emitter Amplifier

I'm having some trouble understanding the behaviour of the basic common emitter fixed bias amplifier. I've been looking at this for awhile now and I'm starting to think there is a foundational ...
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2answers
86 views

R_on for inverter gate

What \$R_{on}\$ do I use to calculate the delay for an inverter gate? In my class we came up with two definitions of \$R_{on}\$, one for saturation and one for triode. Is there a certain mode I ...
2
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1answer
445 views

Schmitt Trigger: Problems between theory and reality

I want to say that I am not a native English speaker so you may find some writing errors. Also, I am just learning electronics, so sorry if some questions are poorly formulated. I am trying to build ...
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1answer
603 views

Arduino - Using NPN transistor as a switch to pull-up/down analog pin

Let me start by saying that I am not an EE, and my knowledge in Electronics is basic, so please bear with me and be patient if, initially I am bending a few rules. In Epee fencing, a touch is awarded ...
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1answer
231 views

Diode connected transistor for voltage biasing

I am trying hard to demonstrate that the transistor M1 in figure works always in linear region. Transistor M2 is diode connected and consenquently (I am using the EKV model) it works always in ...
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72 views

How does a MOSFET conduct in saturation region?

It is a simple question but I could not find a straightforward answer. When a MOSFET enters saturation region, the channel length starts to decrease, and the channel width is the smallest near the ...
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78 views

Way of powering Arduino+GSM Modem+Cam off 5V powerbank

I'm trying to build a circuit, that would turn the Arduino on by a PIR sensor, take the picture by ArduCam, then transfer it onto a webserver. I got the SW site covered by now, so that is not a big ...
2
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1answer
196 views

Is the Gummel-Poon model useful for explaining AC transistor amplification?

Let me be clear: By amplification I am talking about the process of boosting the strength of an AC signal. Thus, where the output power to input power ratio is greater than 1. Now suppose we have a ...
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311 views

Mextram Spice Model for Transistor

Where should I look for a Spice Mextram model for commercial transistors, such as the FMMT415? or Should I try a more advanced analog simulation software, incorporating Mextram or similar transistor ...
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3answers
371 views

Common collector transistor

According to my understanding the common collector transistor should be like figure-1 but in book it is given as figure-2 and in it Vcc is given.Can anyone provide me proper explanation of this.
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126 views

design audio amplifier circuit

I wish to design audio amplifier circuit. Hear I use two stage of amplifiers. 1st stage amplifies 100mv to 1.2V peak @ 2KHz. Q1. When I change the frequency to 50Hz output becomes to 210mv peak ...
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1answer
1k views

Designing a VHF Colpitts oscillator using BJT

I am trying to design an Oscillator circuit which can produce a good sine wave with a frequency of at least 500 Mhz and oscillating voltage of around 10 - 15 volts. The output of this oscillator will ...

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