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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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Hello, this is not my circuit. but I'm playing with it, and I have some questions

hello. First, this is not my circuit. Second, I'm newbie student. I just started studying electronic circuit two weeks ago. I'm just playing with this Circuit. just poking around.. I have some ...
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4answers
345 views

What are the limiting factors of these op-amps?

I designed a multiple feedback band pass filter ...
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1answer
26 views

Inversion Region

If one transistor in a circuit (say common source with active load) operate at the strong inversion region, should the rest of the transistor also operate on that same region? Or will it depend?
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2answers
58 views

Calculating necessary transistor for LED switching

I have only just started to play with electronics (literally less than a week ago) and have purchased myself some cheap Arduino Nano clones, as well as some LEDs, resistors (only 10 ohms at the moment,...
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1answer
42 views

Choosing transistor for amplifier

I'm going to design amplifier, requirement is that impedance for in should be more than 20kohm, impedance for out should be less than 50ohm, and voltage gain should be more than 200. So I'll make cc-...
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1answer
80 views

What's the purpose of using PNP transistors on I2S bus?

What could be the reason of using these 3 PNP transistors on I2S bus (LRCK, BCK and DATA pins)? The DAC used in this schematic is PCM5102. I know for sure that this DAC would work without these ...
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2answers
43 views

ULN2003 Saturation Voltage help

I'm busy designed a PCB that will use a Raspberry Pi's GPIOs to to drive several optoisolators. Additionally I'm also interfacing with an IO module that works with HIGH > 1V. Because of the number ...
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2answers
59 views

How much current will this LED draw?

Sorry if this is a really basic question - software engineer here, so I'm a little out of my element. I'm working on an IoT project, and I'm planning on using this button with a red LED inside of it. ...
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1answer
124 views

Idéas for generating a “half circle” voltage signal from a trigger [on hold]

Here's a tricky one. I'm trying to come up with a circuit which generates the below signal from a trigger: These are the rules: Possible delay between trigger and start of the "half circle" must be ...
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0answers
17 views

Polysilicon Emitter equivalent for PNP BJT

I recently read (in the book semiconductor device fundamentals by Pierre about polysilicon emitter technique used in a n-p-n Bipolar Junction Transistor (BJT) to enchance the current gain of BJT. I ...
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3answers
562 views

This is not my circuit, but anyway, What are they?

Hello. This is not my circuit, but I found it on Google. I'm just a newbie student, so I have two questions. Please, help me. (I started studying electronic circuit last week) 1) The meaning of ...
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2answers
1k views

Will these two transistors (BC558A and BC558B) function in the same way?

I'm currently following this guide on making an Arduino OpenTherm Controller. After finding almost all of the parts without any issue; my only question remained with the "PNP transistor" named in the ...
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1answer
32 views

Common Collector Amplifier and its name

Why is Common Collector amplifier is also known as Emitter Follower?
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0answers
21 views

Clarifications on Intrinsic Gain

I found this here while searching for questions regarding intrinsic gain but I'm still quite confused and the links given were dead. My questions are: Is intrinsic gain the maximum gain of a ...
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1answer
54 views

PIC 10F200 MCLR PIN as Output

I need To use MCLR pin to make led blinking using this configuration but I conn't write the code for that
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1answer
31 views

NMOS/PMOS Saturation

If I recall correctly, saturation occurs if \$V_{GS}>V_{TH}\$ and \$V_{DS}>V_{Dsat}\$ for NMOS. But is there an upper limit for the voltage? Like, when does a transistor not saturate after ...
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3answers
92 views

Inexplicable base bias

I have a common emitter amplifier on my breadboard (the same circuit as the image) with the following values: C = .01uF, R1 = R2=15k, RL = 5k, RE = 1k, and Vcc= 10v. The reason I have R1= R2 is I ...
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2answers
50 views

BJT analysis resistance at the base using voltage divider

im currently confused as to why the resistance at the base is R1 || R2, ive done some research and looked at a couple of responses from people. But i still dont quite understand, could someone help me ...
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2answers
68 views

NPN transistor numerical

I think the steps will be STEP-1: \$V_x - V_{BE} = I_B\times R_E\$ STEP-2: \$I_B = I_{ra} - I_{rb}\$ STEP-3: \$V_x = V_{in}\times R_B/(R_B+R_A)\$ Please tell me i am correct or not??
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1answer
105 views

What does a transistor do? [closed]

Let's say I have a regular motor circuit using an arduino. The motor is a standard motor with a motor controller and I connect it to my arduino and get the code working but I realize that the motor is ...
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6answers
185 views

Simple LED fade circuit

I've been looking for a simple LED fade in/fade out circuit when power is turned on/off for a 12 V LED. I have tried the following circuits but the problem is that I can't reach the full brightness of ...
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1answer
51 views

Stepper Motor Voltage

I am having a problem making a stepper motor run. The problem is that the voltages that I am reading from the motor never reach zero (they move from a high voltage to a smaller voltage) so they never ...
0
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1answer
29 views

How does Dc biasing affect the Q point BJT

In order to amplify an AC signal, its required to provide a DC offset in order for no negative values of current to go through the input. Input signals and output signals oscillate centred on the Q ...
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1answer
25 views

ESP-01 boots with GPIOs HIGH

I'm trying to implement a "button pusher" with some transistors controlled by an ESP-01 module, to push buttons on a remote control. I'm having an issue where if when the GPIOs (I'm using 0, 2, and 3) ...
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1answer
51 views

The BJT characteristic curve

Lets say you want to operate at 20uA base current. To move along that 20uA graph, you need to vary Vce. But to vary Vce, you either vary Vb (voltage at base) or change the values of the resistors at ...
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1answer
49 views

What does the DC load in BJT mean?

I see a dc load line, what is the purpose of this line? There are 2 points i see, Ic(sat) and Vcc Does it have something to do with the maximum current through the device and the maximum voltage ...
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2answers
67 views

Gain of a feedback amplifier with base to collector resistor [closed]

I'm able to solve this problem using the concept of Miller resisitance however I'm having an issue solving this problem using the concept of feedback amplifiers. Can someone help me solve this problem ...
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2answers
36 views

How do the areas of the emitter, base and collector affect their respective currents?

I want to know what will be the effect on current if we change(increase or decrease) the area of the emitter, base, and collector. For example, if we double the emitter area what will be the effect on ...
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1answer
58 views

In practical BJTs, why can't Vce become 0 when the transistor is saturated?

Practically it is about 0.2 V when saturation starts. Why can't it go to 0?
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1answer
97 views

How MCU provides an output to pins [duplicate]

I would like to know how does MCU provide it's output current. here is a little drawing of my assumption (simplified) of how a pin is functioning when it is set to output. Basically it is a ...
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1answer
42 views

Phase shift in ce configuration

Please explain,How a 180 phase shift occurs in "ce" Amplifier. Change in input voltage leads to change in output voltage is some how I know, but this happen in "cb" Configuration too. When Vbe ...
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0answers
34 views

Transistor that keeps on-state or off-state without continuous electrical signal to the base? [duplicate]

Are there any transistor that keeps on-state or off state without continuous electrical signal to the base when used as a switch? I mean like light (mechanical)switch it turn light on or off without ...
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1answer
48 views

Bipolar transistor as a switch. Cut off mode?

I have a question regarding bipolar transistor and it's operation as a switch. I know that, in order to make transistor work as a switch, we need to avoid active region, meaning, we need to make ...
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1answer
35 views

BJT circuit current analysis

Why is the current into the base Ib=Vbb-Vbe/10k? And not just Ib = Vbb/10k?
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1answer
86 views

BJT: Why do we need Rc and Re?

The below graph shows a graph for a BJT with Ic against Vce. Depending on Vce, there is saturation region, active region and breakdown region. These are resposible for different operations. In the ...
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1answer
48 views

Analysis of BJT transistor circuit

in the image, 2 loops are formed, is it possible to form a loop for the last one? If so, what equation would arise?
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1answer
26 views

Some questions about a transistor latch?

Below is a latch made up of two transistors: When the base current of Q2 is increaased this increases also the base current of Q1 which in turn increases the base current of Q2 more. So by such ...
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1answer
28 views

NMOS/PMOS Characterization

I have some questions regarding NMOS/PMOS characterization. I'm designing a common source amplifier using gm/Id method and since it requires characterization, I did so but using minimum lengths and ...
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1answer
46 views

Charge Pump Circuit explaination

I am trying to understand a charge pump circuit here but one part has me scratching my head and this sort of scenario happens a lot with me in electronics. It’s a question of what happened first?? If ...
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1answer
53 views

How to build a timer horn? [closed]

I just know the basics of transistor and all and want to build a circuit that will make a particular sound for few seconds after every hour. How should I begin with it?
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1answer
40 views

Connecting an IR receiver to Transistor for current control

I thought I had a simple circuit ready but I need help finishing it off. I’m using an IR receiver, transistor and a matrix of four 3MM LEDs. Want the LEDs to turn ON only when IR is detected. Using ...
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1answer
60 views

NPN Transistor- max power

I have studied the datasheet of an NPN transistor, in datasheet MAX-POWER OF transistor is mention as 400 mW. What is the meaning of max power? Can it be generated by itself or do I have to give 400 ...
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2answers
93 views

Shorting capacitors using a transistor?

Introduction First off, I'd like to let you know I am a beginner at electronics so some of the stuff I say might be very wrong. What I want to make is a 'spark generator' for lighting some gases in ...
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1answer
53 views

Transistors, explanation of current gain

At this first picture i have a NPN transistor with Beta=75, 2N222A transistor, both Inputs are 5V. it was very simple to calculate the current that will flow through the LED. as it is simply I1 * Beta ...
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3answers
35 views

For MMBT2222; How to get hfe value to calcluate minimum base current to drive transistor in Saturation?

If my collector current VCC = 3.3V & Ic = 31.82uA then how to calculate minimum base current is required put transistor in saturation mode? Depending on it I will calculate base series resistor ...
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5answers
169 views

Emitter Resistor

Why is there a voltage drop of 2v across the C/E in the following circuit (XMM2)? I thought that a transistor behaves like a variable resistor, in that when you apply 0.7v across the base, it's like ...
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0answers
37 views

Transistor as switch (in Saturation mode) - Why transistor saturation appears early with increase in collector resistor

This image is a simulation of a 2N2222 transistor as a switch to level shift 12V I/O signal to MCU compatible 3.3V I/O input. Simulation is done on LTSPICE XVII with DC sweep analysis of V2 (12V) (...
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1answer
22 views

Circuit to a/b switch like a relay would. So an analog or digital signal can be turned on or off or routed

I need to build an arduino-based switcher / router for a multi-arcade to route controls to different game boards, and also switch 2 vga inputs into one output. Without introducing any lag also. 3 ...
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0answers
37 views

Digital Integrated Circuit layouts with Magic transfering to sue schematic

I am working on a assignment using a editor software to design layouts with called Magic and a schematic diagram editor software called sue. For the assignment the problem is to take a existing .mag ...
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2answers
126 views

Suitable transistors for adaptive motorcycle light project

simulate this circuit – Schematic created using CircuitLab I am working on something very similar to this, Adaptive LED Headlights – Model 8790 Adaptive 2 as a hobby project. I have controller ...