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

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Use Arduino(5V) to switch a 3.3V

I have a HDMI switch that i want to control with an Arduino. It's working by pressing a button to change input signal. The button is NC(Normally Close). By pressing the button you break the 3.3V going ...
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1answer
20 views

Polarity of feedback in a feedback circuit

How should I check whether the given configuration has a negative or positive feedback. I am stuck because, I know that as Vin increases the drain current will increase but after that I don't know ...
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What is the difference between a bioplar junction transistor (BJT) and a field effect transistor FET? [on hold]

I read somewhere that BJT's amplify current while FET's amplify voltage (correct me if I'm wrong). I'm not necessarily looking for how they work on a quantum level. Just wondering about the ...
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1answer
37 views

How to use 2 power supplies in transistor key?

I have 2 power supplies in my scheme, one is from Raspberry Pi GPIO and one is 9v battery. I need GPIO output to work like a button, e.g. when output from GPIO is 1, battery should power the scheme ...
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6answers
148 views

Implementation of a NOT gate with two transistors - Why not one?

I just encountered this implementation of a NOT gate: My question is: Why do we need the lower transistor? Why can't we do this: Thanks!
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1answer
103 views

Burning out relays when supposed to be within ratings

I am using this Normally Closed Relay on a 24V circuit: DataSheet The circuit is 24VDC source, which I measured the Amperage in series to be 29mA at the highest. I've breadboarded a lower voltage ...
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0answers
20 views

433 Mhz + Attiny85 improve range

I want to send information from my Attiny85 to my Raspberry. For the moment. Attiny and Emitter work on 5V Emitter have a 433 Mhz 1/2 waveform antenna I'am using virtual wire Raspberry receiver work ...
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1answer
108 views

How do I calculate the base and collector current in this circuit?

I have the following circuit, using a BJT NPN transistor: How can we calculate the current going into the base and collector? I was thinking of using Kirchoff's current law: \$I_1 = I_b + I_c\$ ...
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2answers
126 views

Simple circuit to convert a toggle switch turning on into a short pulse

I need to convert a permanent high signal into a short high pulse. I've got a design problem where I have a toggle switch that connects to a variable +11V to +17V power source, providing a signal to ...
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1answer
69 views

Who triggers transistors to become H/L?

Admittedly that's quite a beginner question: When I learned that transistors work like relays and produce the digital values 0 and 1 what I always asked myself was: they have to be triggered by ...
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1answer
60 views

How do I energize a 12v relay coil using a 2N2222 bipolar transistor?

I'm relatively new to working with transistors, and I'm having some trouble getting this circuit to work. I want to use an Arduino's I/O pins (5V out) to energize a 12V relay coil. To do this, I'm ...
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2answers
42 views

Can I use 2n2222 transistor instead of c9013 transistor in a vu meter?

I am building a science project for my friend. We chose to make a VU Meter. I am planning to make the Vu Meter as the schematic in the image: The audio source will be 3.5mm jack output of a ...
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1answer
22 views

uln2803apg toshiba shows noise

I'm using an arduino to send a 5v signal to other devices. I'm using the uln2803apg to drive a 5v 3ampere signal. The problem, when i look at this output signal i'm seeing a lot of noise, which is ...
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1answer
46 views

comparison of amplification by CE amplifer and an op-amp [closed]

What are the differences in working of a common emitter amplifier and an op-amp? They both contain transistors, so what causes the difference and what are the differences?
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1answer
64 views

Questions about a simple LED circuit using the ULN2003A

I'm a newbie, and am trying to drive several independent LEDs using a transistor array in a 5-volt CMOS circuit. Here's what I've come up with, showing only the first LED: In the schematic, ...
4
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1answer
301 views

Why might the collector-emitter voltage for this transistor be so high?

I'm attempting to use an NPN transistor as a switch, to drive an LED load. So I am only interested in the off and saturated states. My understanding is that when the base-emitter junction is ...
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3answers
60 views

Why is voltage output inverted between common-emitter and common-collector amplifiers?

My resource shows the following common-emitter transistor configuration and claims that the output voltage compared to the input voltage is inverted (higher input voltage means lower output voltage): ...
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0answers
49 views

Finding the input resistance of an NPN transistor

The question is asking to find the input resistance of the circuit shown in the picture. R_in "starting" position is shown as well. I have done quite a few problems involving replacing the ...
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1answer
71 views

Will there still be small voltage in transistor OFF state?

In Bipolar junction NPN transistor which has three legs as shown below: Case 1: If this transistor is in OFF state i.e. collector is connected to +Vcc and Base is connected to insufficient voltage ...
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1answer
66 views

Controlling multiple RGB leds with PWM from a Atmega328P using one transistor per color

I want to be able to control 9 RGB leds, each color from a potentiometer. Each color needs 20mA, so when all the colors are present the leds will need 540mA (9*3=27, 27*20mA=540mA). My RGBs leds are ...
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2answers
1k views

What is the use of the transistor in this circuit?

This is an LED driver circuit, but what is the use of the transistor in it?
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1answer
59 views

Replacing a relay with transistors in this step down circuit

I've made a simple circuit to step down voltage from 12V+ to around 5V, and while it works, it is noisy and it requires much capacitance. I would prefer to make it using transistors instead of relays. ...
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1answer
52 views

what would the drain voltage be if NMOS source voltage is not ground?

Hi I'm a beginner trying to learn CMOS cuicuit. Let's say we have two NMOS connected as shown. Given: A, B, C are connected to Vdd = 5V; VtM1 = 0.6V is the threshold voltage of M1; VtM2 = 0.5V ...
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2answers
348 views

How to figure out which transistor amplifies the signal?

Suppose I have the following circuit: How can I determine which transistor amplifies the signal and which transistor is just a simple resistor? Also if is a resistor how can I determine it's ...
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0answers
58 views

Discrete BJT Voltage Controlled Op-Amp

I recently asked about building a transistor controlled variable gain differential amplifier for a project I'm working on. The configuration I used was less than ideal and I am researching different ...
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1answer
48 views

Differential gain of amplifier with current mirror

Consider this pdf document, pages 58-59-60. It is a differential amplifier with a current mirror as active load. According to that document, if I take the unbalanced output in the right-hand branch ...
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1answer
371 views

How protective diode protects transistor from breakdown?

Please, explain the process of breakdown; how exactly this protective diode protects the transistor? In a Horowitz & Hill book, "The Art of Electronics", 2nd edition, in "Chapter 2 - Transistors" ...
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1answer
44 views

closing a circuit programatically if ground can't be interrupted

I need to be able to "push" a button on a control panel using python and an arduino board. My problem here is that the button in question, when depressed, sends 16 vdc to an outgoing wire that ...
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4answers
232 views

Semaphore using one microcontroller pin

I'm trying to make a semaphore using to LEDs green and red, controlled by one arduino pin. Idea is when pin is low red LED is on and green LED is off, when pin is up green LED is on and red LED is ...
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1answer
242 views

Why use a N channel MOSFET as high side H bridge switches?

I've seen N channel MOSFETs as high side switches of H bridges quite often, which requires a charge pump to drive. Wouldn't a P channel MOSFET be easier, simply isolating the microcontroller command ...
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0answers
86 views

Light emiting transistors?

It's crazy idea, but i wondering if it's possible to build some blinking multivibrator circuit without any leds, where transistors emit light themselves, it would be cool :) I googled and it seems ...
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3answers
502 views

What is the difference between a solid state relay and a transistor?

Along with the difference between a solid state relay and a transistor, I'm also interested to know if there are transistors that act a lot like the typical relay modules you can find on ebay (where ...
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1answer
62 views

Simple High Side IGBT Switch

I'm trying to design a capacitor discharge circuit for a hobby rocket launching system. In some cases we have long wire runs with multiple rockets so a CD circuit seemed the way to go. I'm trying to ...
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68 views

Can't figure out circuit analysis

The original homework problem is as follows: I have the solution from the professor, but I don't understand why he rewrites the model the way he does, and I also don't understand the derivation of ...
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43 views

Vape Pen Circuit, 3 main components. Wiring/component help?

I'm looking to control a vapor pen with a variable voltage (adjustable PWM that dictates a MOSFET), followed by a SPST toggle (safety), followed by a momentary that dictates another MOSFET. The goal ...
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1answer
43 views

Viability of Voltage Controlled Amplifier circuit

As part of the synthesizer project I have been working to design a simple voltage controlled amplifier. Due to the complexity of other parts of the circuit and the amount of time I've spent on this ...
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1answer
60 views

What does “2N363PNP” mean?

Recently I did the experiment of input and output characteristics of BJT and I saw that "2N363PNP" was written on it.I want to know what does it mean? Is it only a name ?I can guess that it is a PNP ...
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1answer
60 views

Voltage used up by a transistor and shift registers

i am on a project 8x8x8 LED cube and I am stuck on the value of register i should use. Talking about single layer I am using 2N5296 transistor for common cathode and 8 shift registers for controlling ...
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3answers
72 views

Current Limiter, can someone troubleshoot this circuit?

so I am trying to limit the current output with x2 3904 transistors and a sensing resistor. This is currently what I have, but am not sure why it doesn't work. That current supply is going to be a ...
0
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1answer
44 views

How do I select transistors for logarithmic amplifier?

I need a logarithmic amplifier and found this equivalent schematic in the datasheet for the LOG104: The LOG104 is rather expensive, so I want to build this myself. What are the requirements for the ...
2
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2answers
162 views

What (if any) is the leakage current through a NPN (C-E)?

So I have a circuit where I need the current consumption to be low. Therefore I am using a 10M\$\Omega\$ resistor to 'pull-up' the pin on a chip which will need to be switched between high and ground ...
2
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1answer
145 views

Can someone explain how this transistor comparator works?

I am looking to make a comparator using transistors and I stumble across this circuit claiming to be one: Unfortunately, the description that came along with it leaves a lot to be desired, ...
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1answer
59 views

Which Material is used for High Speed Devices Germanium or Silicon & Why?

Actually i am get confused with electron mobility & it's role in deciding a material for Some particular application.
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1answer
124 views

RPI with power supply alternating between Li-ion battery pack and DC 5V

I have a Raspberry Pi model B+ and I've been trying to design a solution so that I can switch power supply without having to shutdown. The idea is this: I have 2 li-ion 18650 batteries with ...
0
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1answer
107 views

Help on transistors or MOSFET in 8x8x8 LED cube

I am on a project to build a 8x8x8 LED cube having common cathodes in each layer. I have built the cube and now I have to build the main circuit. I am using my Arduino Mega 2560 to control it. I ...
0
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1answer
79 views

Darlington pair base resistor value calculating

Let me know how to calculate the TR1 base resistor value in the following darlington pair and also explain the role of pull up and pull down resistor in a circuit thank you.
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1answer
50 views

Will this circuit work using BC 108 transistor

Hi guys i have circuit diagram from everyday practical electronics magzine and i want to make it but there are two problem about the circuits one is the transistor BC 108 used in this circuit and the ...
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1answer
50 views

Can I use a 2N3904 transistor in place of a 2N4401 if I flip it around?

I want to do a composite video mod for a Colecovision. The mod (http://www.benheck.com/Games/Coleco/Video_Mod.htm) calls for an ...
0
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3answers
37 views

Electronitc switch without common contact

As I understand it, a transistor can be schematically described as a variable resistor controlled by a tension (when it is correctly biased). That is, the resistance between emitter and collector is ...
12
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4answers
479 views

Transistor S8050 D 331 at 1MHz

Firstly let me tell you, I don't have much knowledge about the transistors in circuits. I am having a transistor S8050 D 331, and it's connected like on the schematic below. The problem I am having is ...