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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How can you calculate base voltage of a transistor when there are biasing resistor and a resistor between 2 input terminal

I just get to know about transistor a little. Here is my question As you can see that here the transistor is configured to be an amplifier in common emitter mode. R1 here is the bias resistor. What ...
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43 views

Load cell without In-amp

I have a 0-1kg load cell with 4 wires: Excitation + and -, and Signal + and -. I haven't had any problems wiring them up correctly without amplification, and my voltmeter shows me a 1 mV difference ...
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533 views

AC equivalent circuit of transistor

For AC equivalent circuits, it is written that, in the case of small input signals the emitter diode does not rectify, instead it offers a resistance called AC resistance. Why is this so? Why doesn't ...
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Photo-Interrupter Usage

One of the projects I am working on requires a number of photo-interrupters to be used. I was wondering if someone could explain how to use them correctly? I was thinking something like this: ...
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70 views

common emitter problem

I have this problem to solve where I1 = 6mA, beta=125 and Vbe =0.6V So far I have solved the following, a. How circuit works? Circuit works as a stable output voltage source. This is caused by ...
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105 views

Output impedance refers to open circuit o/p impedance or short circuit o/p impedance?

When we specify output impedance of a two port network, does it imply open circuit output impedance or short circuit output impedance? Wikipedia: output impedance ; Wikipedia: two-port network g22 ...
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83 views

. 5 volt to control a 3 volt signal

I need to find a transistor that can use the ~.5vdc signal from my phone's 1/8 audio jack to control a 3vdc signal. This may be a stupid question but I am a beginner.
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2answers
75 views

Using a DC voltage as the base for a transistor to amplify AC Voltage

I'm a little new to electronics, particularly transistors, so I don't know a lot of the different types and inner-workings of them. I have a diagram which, hopefully, will gradually increase the ...
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40 views

Transistor Alternatives [on hold]

Is there a website that suggests alternatives to components? For example, there are many companies making transistors and their specific products specification can sometimes be very similar, but ...
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72 views

2 Transistor XOR Cell Floating Output Problem

I designed the following 2T XOR cell for my full adder purpose: Theoretically it gives correct output for all input combinations. But on Tanner Eda using 180nm technology 5V supply, it gives logic ...
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70 views

6 Transistor Full Adder

I am working on a 6 Transistor Full Adder whose circuit diagram is The circuit works fine but there is a problem: it needs a 25k resistor at XNOR and SUM point to show the complete Full Adder ...
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204 views

Why my transistor switched when base was grounded?

I am from a programming background, so I dont quite know the theory, But I want to control a motor from a mictrocontroller. So I used a TIP 122 to do it. My circuit looks a bit like this: ...
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79 views

8 Transistor Full Adder

I am working on 8 Transistor full adder which is based on 3 Transistor XOR cell. I have studied many IEEE Papers for 8 Transistor Full adder. All have same ckt as above.But the full adder is not ...
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1answer
46 views

Why can current flow through the reverse biased base-collector junction (N-P junction) in a BJT with a forward biased base-emitter junction?

If the base-emitter junction of a BJT is forward biased, then current can flow through the reverse biased base-collector junction (N-P junction). This disagrees with my understanding of the PN ...
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1answer
50 views

Driving 259mA stepper motor with a 2N4401

A while ago I asked a question about driving a stepper motor using a 2N5550 and was advised that it wasn't really capable/a good idea. I received a good answer but would like a bit more information ...
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1answer
48 views

Calculationg base-resistor between microcontroller and transistor

I'm curious, when connecting my 2N2222 transistor's base to a PWM output pin on my Arduino, I know the Arduino can deliver a maximum of 40mA current. The 2N2222 only requires around 5 to 10 mA on it's ...
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65 views

What is “pull the collector below ground” and saturation

I can't come up with any suitable title. I am reading about transistor from a book Here's the 4 properties of an NPN transistor (for PNP, it is reversed) The collector must be more positive ...
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838 views

Why can't you go sticking a voltage across the base-emitter terminals in a transistor?

I just read some first pages of "The art of electronics - Paul Horowitz". In chapter 2 transistor it says there are four properties of an NPN transistor (for PNP, it is reversed). The 2nd property ...
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1answer
57 views

Which kinds of FET have a body diode

I need to detect small high and low peaks in the battery voltage while in use. The goal is to help estimating the end of the battery charge by its change in impedance, since my circuit uses the ...
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79 views

Simple NOR gate (transistor-level) diagram

My question here is simple: I cannot understand how the input flows throughout the circuit. I understand the P and N type transistors; I could see why if A and B are both 0, and pass through the ...
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1answer
80 views

DC Voltage Source - circuit problem

I'm currently trying to build a DC voltage source from an AC source to a school project. The circuit worked fine when it had no voltage regulator, as it was just a transformer + full-wave rectifier + ...
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0answers
17 views

HSpice optimization of parameters not achieving desired value

I use HSpice. I have a spice netlist wherein the TPHL and TPLH of my circuit should be less than 3%. I use the Spice optimization parameter as indicated here ...
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1answer
63 views

Transistor Level Shifting in Buck-Boost Converter

Ive been reading some of the LT application notes on Jim William's Analog Circuit Design book, and there's something I don't quite understand. I'm attaching a scan of the circuit in question. The ...
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67 views

Voltage limiter is shutting down completely when tripped

What the circuit is designed to do The following circuit is designed to accept a rectified (low frequency) sinewave input of amplitude 0-30V, and filter it through charging a capacitor until its ...
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296 views

Stiff Voltage Divider Bias for an Emitter Follower

Below is an ac-coupled emitter follower with base bias provided by a voltage divider. I'm having a slight issue with how the resistor values are chosen for the biasing in the design example provided ...
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338 views

How is this circuit for interfacing 20V signal with 3v3 microcontroller

I have designed the following circuit to interface a 12-20V signal to a microcontroller running on 3.3 volts. The signal is either 20V or open circuit. I want the circuit to be as resilient as ...
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49 views

How ICBO gets amplified to ICEO in BJT when base is open

I have been doing some reading about ICEO and ICBO, but couldn't really understand how ICBO is getting amplified (1+ beta) times to reach ICEO, in the open base condition. This is my understanding ...
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42 views

ICEO, ICBO physical interpretation in BJT

I am stuck with the equation: ICEO = (1+β) ICBO My questions are: What is the physical interpretation of this equation? Will both the currents exist simultaneously? Are any of the reverse currents ...
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60 views

How do you perform circuit calculations for the darlington pair

I need to know what formulas or set of calculations would be used to figure out the base resistor and load resistors when hooking up a darlington pair as my datasheet for the ds2003 does not provide a ...
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120 views

What does it mean for a transistor to be biased beyond cutoff?

I understand what it means for the transistor to be biased for Class A, AB, and B with regards to the location of their DC operating points (\$I_{C_Q}\$ and \$V_{CE_Q}\$ are found by finding the point ...
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64 views

Why increase in resistance of register used in circuit show lesser average power dissipation

I am working on 6 transistor full adder circuit. Red marked resistors (25k) are used to show all pattern of full adder correctly. But it show wired behavior. When I increase resistance from 25k to ...
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647 views

How to get more current from 555 timer?

My power supply is filtered regulated 5 volt 500 mA . I am using a 555 in monostable mode to switch the motor on for a certain amount of time after the 555 is trigerred. (The 555 is being trigerred by ...
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1answer
62 views

Bipolar transistor switch base current calculation example from PEFI seems wrong?

I'm reading through Practical Electronics for Inventors, 3rd edition, on bipolar transistors, and they provide this example of a transistor switch: I'm a bit confused by the calculation at the ...
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132 views

Reducing Ripple in the Zener Regulator

In the Art of Electronics (Horowitz & Hill) the following circuit is given as a solution to reduce ripple current caused be variations in input voltage (pg. \$ 69 \$): "An alternative method ...
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What does 25°C mean on a transistor data sheet?

The background is, I'm trying to understand how well a typical transistor obeys the Ebers-Moll equation at constant (junction) temperature. See this snapshot taken from the Fairchild datasheet of the ...
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1answer
68 views

Trouble with first part of Experiment 11 (Make: Electronics)

Experiment 11 from Make: Electronics Hi, this'd be my first forum post. I'm really out of options here. Let me get straight to the point. I bought the book "Make: Electronics by Charles Platt" a ...
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3answers
82 views

How do I keep my constant current source constant?

So I am trying to created a current source that will be used to drain a battery at specific time intervals for a specified duration. simulate this circuit – Schematic created using ...
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1answer
93 views

Help interpreting TIP127 datasheet

I'm trying to build a constant current 2A amplifier using a TIP 127. To be honest, I have a lack of transistor knowledge. I decided to analyze a few existent circuits with a TIP127 and the datasheet. ...
2
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1answer
263 views

LEDs flash at the same time and not one at a time

As you can see on the illustration below, I have a voltage supply (a keyboard made of two piezo elements) with two terminals. Each one drives one LED, but since I've added a buzzer in parallel with ...
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1answer
28 views

making Tphl and Tplh equal

Let's say we have the following netlist ...
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1answer
149 views

Designing a current limiting circuit for my project

I've got a small DC brushless motor for which I would like to set a current limiting circuit as a protection against over-current. I thought I could pull it off with a simple fuse (or those current ...
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73 views

2n3055 replacement with MOSFETs

I have searched a simple circuit diagram for a 12v to 220v voltage inverter. The circuit has two 2n3055 transistors and I presume it is used for switching. Can I replace them with IRFP250 MOSFETs ...
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211 views

Is there any way of making this circuit simpler?

I had earlier asked a question, Will this circuit for quiz buzzers work?, in which I got a very good answer (The first one). But I have some problem in that circuit and I am not able to make it ...
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44 views

Voltage transfer characteristics of a C-mos inverter

How to determine the voltage transfer characteristics of a c-mos inverter during the region when both the p-mos and the n-mos transistors are in the saturation region.I know that both the transistors ...
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1answer
41 views

Switching power between two 7-segment displays using NPN transistors

So, I am working on a small project and forgot to order PNP transistors to switch the power to two common-anode 7-segment displays. Like this, for example: All I have in hand at the moment is a ...
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28 views

Using n-mos and p-mos transistors as pass transistors! [duplicate]

The n-mos passes a good '0' and the p-mos passes a good '1'.What is the logic behind this?Can anyone suggest a proper book to study Vlsi design?
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141 views

Make a zener diode out of a MOSFET

Does anyone know if its possible to wire up a MOSFET transistor as a zener diode? I have been happily making normal diodes from my MOSFETs by shorting the gate and the source simulate this ...
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48 views

Power Transistor Help

I'm looking to switch an 18v signal at 1 amp with a N-Channel power MOSFET with at least 1.5v to turn it on in a TO-220 package but unfortunately I've only been able to find this one from Fairchild: ...
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44 views

Replacing a transistor in a CCFL inverter circuit

I have a DC-to-AC inverter circuit that isn't working. It takes 12V DC input and is being used to power a CCFL. The circuit looks remarkably similar to the one labelled "Conventional CCFL inverter" on ...
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Transistor saturates no matter the size of base resistor

Problem I have a circuit as depicted below, and after calculating the base resistor, I wanted to see when the base current would be too little to saturate the transistor. I kept increasing the ...