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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11 views

switching a buck converter with transistor

I've got a bunch of shape memory valves (SMV) that require 1.2V @ 0.25A and I'd like to use a single buck converter and DIO signals from an Arduino to switch these shape memory valves on and off. I'...
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41 views

Controlling Proportional valve with NPN transistor (TIP 122) using PWM

We are working to control the proportional solenoid valve (9C, 2W) (VSO by parker, datasheet) by changing the voltage across it. For this we are using PWM from the controller, thus changing the ...
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32 views

Turn LED OFF when load is disconnected

This is my existing system, I would like to Add a LED indicator which will turn off when the Lamp get burned/damage. Someone told me to use transistor but am not sure which transistor, where and how ...
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26 views

Designing simple class a amplifier using mosfet

I'm trying to build a simple class a amplifier using a mosfet. I have read few articles about how to do it, but I'm just confused now. I'm not sure how to select resistor values. The articles I've ...
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Required to find resistor values for a Class B push-pull amplifier biased at cutoff region [closed]

I am required to determine the values of R4 and R5. Vcc is given at 9V and the circuit is biased at the cutoff region. Any help is appreciated, thanks!
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109 views

Why is transistor needed when using a relay?

I will start building a relay based on this answer: https://electronics.stackexchange.com/a/464345/56969 Why is T1 needed? Every other component has an important purpose. But does T1 has an ...
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53 views

How to select a transistor

I am building a quadcopter and would like to figure out a transistor I can use to switch the FPV (First Person View - onboard camera connected to video transmission system so the drone pilot flies ...
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1answer
83 views

What is meant by the MOSFET is pinched-off?

What is meant by the MOSFET is pinched-off? It is same as in the JFET case where the depletion region becomes too large until the electron cannot flow through the transistor?
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59 views

Connecting Solenoid valve in the emitter of the transistor

We are working on a circuit in which we are controlling two way solenoid valve (24V, 10W). We are using 3.3V based controller. The solenoid valve is connected to the controller via TIP 122 (NPN ...
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76 views

Help with output impedance of a circuit

We have to find the output impedance of the following circuit, where the output is the upper pin of R4. If I try to compute it with LTspice, I get about 55 Ohm, but whenever I try to work on it ...
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57 views

What is the purpose of this schottky diode reversed across the BJT base resistor?

In a design for the popular "gotek" floppy drive emulator, as per the standard, the outputs from the floppy emulator are open-collector. An STM32 is used as the processor. This drives a 74HC04, which ...
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50 views

Distortion in Transistor Amplifier

I want to design amplifier in 20kHz - 200 kHz range. I have designed following circuit using BC547 transistor. I have set VCE voltage to 6v and set Q point to the middle of the load line. But when ...
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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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101 views

Design a tuned BJT common emitter amplifier with some specifications

I've been 2 days trying to design such amplifier with the help of a book of Boylestad (Electronic Devices and Circuit Theory), but the best I came with was an amplifier that amplifies what it's ...
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26 views

Common Source Amplifier Pmos?

What is known as a common source amplifier is often built with an NMOS, where the bottom channel (source) is connected to ground. What if you switch out the NMOS with a PMOS, and the bottom channel is ...
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56 views

What will be the effect of adding a 10k load resistor to this circuit?

Background When ignoring the 10k Resistor: When Vsupply = 28V, I have worked out that the current through ZD1 = 4.95mA. When Vsupply = 14V, I have worked out that the current through ZD1 = 4.9mA. ...
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Calculate the collector currents and collector emitter voltages of the transistors [closed]

For transistors used in the circuit used β = 200, | VBE | = 0.6V includes them. Calculate the collector currents and collector emitter voltages of the transistors.
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23 views

Possible over-current issue in Arduino transistor circuit?

I have made the circuit illustrated below. It uses a Sparkfun ProMicro to turn a pump on and off based on the signal from an Adafruit light sensor. I am using a signal from the ProMicro to the 2n2222 ...
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47 views

Darlington transistors killing the output

I was trying to recreate a subwoofer following this website. And the first 2 stages function as expected. The low pass filter is working which i verified , and the the second stage amplifies the peak ...
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52 views

AC coupling of a transistor

So we assume to have proper bias currents flowing in both of the two transistors. What is claimed by books is that a capacitive coupling will not change the bias parameters. But, we know that a ...
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70 views

Is a 2N3906 an appropriate replacement for a BC158(B) in audio amp circuit?

On a long but educational process repairing a vintage German stereo. I have identified a failed (shorted) PNP transistor in the power amp section. (Schematic with highlight is below.) The part on the ...
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1answer
64 views

Design of Class-AB output stage

I'm trying to design an audio amplifier output stage to drive a speaker load. I'd like to start with the design of this stage in order to calculate the input impedence to the output stage so that I ...
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56 views

How can I design the BJT based inverter question given in description?

QUES: Design a BJT based inverter operated from a 1.5 V supply.With the input connected to the 1.5 V supply through a resistance equal to RC, the total power dissipation should be 1 mW and forced β ...
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18 views

lt spice simulations including mosfet

to lt spice users, how do you include a MOSFET into your ltspice circuit? if it helps the mosfet I'm trying to include is IRLZ44N
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55 views

Exceed recommended power supply range on analog switch

I would like to use an analog switch in my design (NLAS5223C). The recommended power supply range is up to 4.5V, and the absolute maximum rating is up to 7.0V (relevant specs attached below.) I'm ...
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why we prefer transistor(Q1) and diode (D5) is used in this circuit? Why we preferred zener diode as reference voltage? [closed]

why we prefer transistor(Q1) and diode (D5) is used in this circuit? Why we preferred Zener diode as reference voltage? What is role of R1, R2, R3, R5, R6, and R7 this this circuit?
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43 views

Transistor base voltage and current

I want to use a transistor to control a 5v power source but Im confused on how to control the base pin. How much voltage can I put on the base pin? I've seen tutorials which use 5v with a 1k resistor,...
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30 views

Half adder with soft latching input buttons

I'm trying to build a half adder with soft-latching buttons as input, using only transistors. I looked up online for some ideas and managed to build a soft-latching input circuit and a half adder ...
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37 views

Understanding the Base voltage of PNP when driving NPN transistor is cut off and there is no clear DC bias voltage

I am studying the Art of Electronics and trying to apply what I have learned to a motor driver circuit from an MITx intro to control systems course (https://www.edx.org/course/introduction-control-...
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75 views

Proof of linearity of a transistor

When we deal with a transistor we break it up into two parts, 1 The DC bias. 2 The small signal perturbations. Then we add the currents/voltages from the both the analysis to get the total response. ...
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Where does Zi = hie+1(1+hfe)RE come from in a BJT from Hybrid Model?

I've been struggling to understand how to get to this expression without knowing about re model (actually, still knowing about it, I can't get to understand this). In a BJT in, how does one get to Zi ...
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40 views

Matrix has a voltage drop on a coil that should not be receiving any current

I am making a matrix of electromagnets (each with about 120 Ohms resistance) and I am using a circuit like this for the columns (low side of the switch): simulate this circuit – Schematic ...
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How to calculate gate capacitances (Cgs,Cgd) of a GaN HEMT?

I have calculated Cgd and Cgs using an analytical model, And I found that the second one is negative for Vgs < Vth, where Vth is threshold voltage and Vgs is the applied voltage. could this be ...
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64 views

Common drain small signal analysis and unresolved question for fet

question: There is an amplifier circuit obtained between JFET and MOSFET. For the FET used in the circuit, IDSS = 8 mA, VGSoff = -3V and working point current is 1.42 mA. Use MOSFET parameters as ...
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43 views

Specific transistor for voltage regulating?

In 2SD1047 NPN transistor datasheet described the application for power supplies and the description is: The device is a NPN transistor manufactured using new BiT-LA (Bipolar transistor for ...
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86 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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61 views

Led-driver (BJT)

Task about BJT Led Circuit: https://www.circuitlab.com/editor/5kx6tz8jk36j/ ]2 To set up the LED driver. The requirements are: The current through the LED should be 20mA ± 1mA The IC/IB should ...
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55 views

BJT NPN Switch not fully turning off under certain conditions

My first post here, I'm relatively new to electronics and this is my first project that I'm trying to accomplish myself. First off, some background of what I'm trying to accomplish. I am trying to ...
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BJT Transistor Open/Low or variable load behavior

How does a BJT react when saturating the base with a very low collector current? For example, 10 mA into the base of a 2n2222a with a collector current of 20 mA in a common collector setup. Will the ...
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154 views

Simple version of an internal op-amp circuit

I'm currently learning how op-amps and transistor circuits work and want to understand the simple version of an internal op-amp circuit. However, there are still some open questions. The first stage ...
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82 views

Wher do Beta comes from?

I've never seen any explanation for why is the Collector current = Beta * Base current. Please if you know give me some derivation for it. No matter if it involves math or something higher level stuff....
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45 views

Switch power on/off when SD card is inserted/removed in slot

I have ESP32 and I'm using it to read/write data from an SD card that is directly connected over SPI. This works fine. Now I want to switch on the ESP32 automatically by switching on the 3.3v power ...
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43 views

Issue with low voltage for mosfet gate

I am a beginner when it comes to electronics so I would appreciate your help with a simple project I am working on and have been struggling with for several days. The idea is that I have a PIR Sensor ...
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57 views

Basic Transistor Transconductance Amplifier - Negative Current Gain?

I'm working through The Art of Electronics. In chapter 2, it breaks a common-emitter amplifier into two stages: a transconductance stage and a resistive load stage (or transresistance amplifier). ...
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62 views

Differential amplifier (transistors): Which input is inverting?

For example, on the following differential amplifier it is clear, which of the inputs is the inverting one. If the voltage on the non-inverting input (base of Q1) is higher, the current through Q1 ...
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31 views

Understanding the working of a NAND GATE using NMOS Transistors

I'm having incredible difficulties understanding how the "Switching Behaviour" (not sure if that's the correct English translation- in German it is "Schaltverhalten") for NMOS and PMOS transistors ...
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How do I amplify the difference between two voltages?

Starting at the beginning: I have a shunt that carries DC current, and the voltage drop is very slight. I want to amplify it in order to see it better on oscilloscope, and to have it scaled correctly ...
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35 views

How can I find the drain transfer function of a MOSFET on LTSpice?

I am trying to get the drain transfer function of a MOSFET by setting the drain to source voltage as the input and the gate to source voltage as the output. I created the following circuit in LTSpice: ...
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39 views

N channel not created help [closed]

I am connecting this power mosfate to gate voltage of 1.7V its electric characteristics say 2.5 max threshold voltage and the source substrate pin to ground and the Mos capacitor made of the substrate-...
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85 views

Is it possible to take the transfer function of a transistor?

I am using a common emitter amplifier to bias and amplify the signal from an electric guitar, and in the process I started wondering whether it is possible to include a transistor in a transfer ...

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