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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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Digital LOGIC MICROELECTRONIC

Whenever I have "input" which it could be HIGH AND LOW for example the input VIN to the CMOS INVERTER then we assume that the iput is 0 or vdd ! what's confusing me who said that high can't be VDD-VT ?...
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Class A amplifier with preamp design

I am currently working on a class A audio amplifier designed to work with line in voltage (about -400mv to +400mv). I plan on using an IRFP240 for the mosfet but am undecided on the transistor stage. ...
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connecting power resistor to arduino as a heater? [on hold]

how do I connect power resistor to a Arduino. it take 15V to reach the temperature I want and I have to maintain the temperature.
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245 views

Emitter resistance in transistor bias

I am having issues with the emitter resistance during biasing of the transistor. Can someone explain me what's the point of using this resistor? It is getting very not intuitive for me.
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What is (was) this component at ZD102 (top left, next to powered serial connector)

Part at ZD102 is overloaded with too much current and blown. It's three legged, with two legs on the south side and 1 on the top. The left side (white in the picture) is blown and has since ...
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Need help identifying this component recovered from a Fostex X28

This has been taken from a Fostex X28 4 track recorder and requires spares. I am not familiar with this component and I am unable to find information online. Does anyone know what it is and if there ...
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How above should a through hole transistor sit on the PCB?

I´m soldering a self-made H bridge with several 547 and 557 TO-92 through hole transistors and I don´t know how high from the PCB should I solder the transistor. I found a tutorial just telling that ...
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Effects of changing the width of transistors

Looking at the figure attached, I want to understand how does increasing x, affect the noise margin of the gate [i.e. (High noise margin) & (Low Noise Margin)]? Also, how does increasing x affect ...
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2-time constant (On + decay) timer circuit

Required is a timer circuit to switch on an LED with 2 time constants, when a switch is depressed as follows: when switch is closed, light an LED 10 ~ 20mA when switch is opened again, keep the LED ...
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Best way to get +5V or +12V or 0V from arduino pin

I am working on an eeprom programmer as an Arduino shield. There are two pins on my eeprom that require a 12V signal as part of the programming process. One of them is an address pin that I am also ...
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142 views

Transistor gain vs circuit gain

In a CE circuit what happens when gain, determined by Rc/Re is greater than transistor beta? i.e. I'm designing an amplifier for 75mhz, I have a 2nF capacitor across Re. I expect the impedance at ...
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input resistance of differential amplifier

i have a question about the differential amplifier i know that the input resistance for the common mode is Rin = rpi + 2 Beta Ree / 2 but my question is what is the input resistance for the ...
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Transistor circuit driving me insane

Consider the following circuit: Now I'm asking to impose the base current as zero and $$R_C=452.35 \Omega $$ Now I have a lot of issues with this circuit because I can't find a systematic way to ...
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168 views

Question regarding operation of a pulse generator circuit with 3 transistors (exercise 2.3 art of electronics)

The exercise 2.3 in 3rd ed. of Art of Electronics asks: what is the output voltage during the pulse? I've replicated the circuit diagram from the book below (in circuitlab.com). I'd be grateful if ...
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133 views

Energy of electrons in npn transistor

Why do the electron loose energy when it moves from base to collector region? In a npn transistor first emitter base junction is forward biased so electrons move to the base region . The electrons are ...
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Which one is the pinch-off voltage?

According to my book and teacher : It is the Gate voltage at which the depletion region closes the channel. According to some people on the internet and Youtube videos: It is the Drain to ...
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387 views

Biasing a second stage amplifier

I built a two-stage amplifier as shown below. I have already built the first satge (R1-R5 & C1-C2) such that If I apply a signal of 1volts peak-peak, the output (at collector of Q1) would be 8 ...
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76 views

How to analyze this opamp circuit with logic gates, Zener diodes and transistors?

This is the circuit with this values: $$\text{Logic gate of CMOS,VTH=2.5v,VCC=5v,Vz=3.3v,Vd=0.7,VBE=0.7}$$: The left side is working like a SR FF , and the right side Schmitt trigger comparator and ...
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451 views

Two-tone alarm issues

I'm working on an inclass project, for a two-tone alarm circuit. The 3V source represents two AA batteries. We've implemented this successfully on a breadboard. The IC used for the Inverted Schmitt ...
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82 views

5V digital output to 24V

I'm sure it is a simple solution but I am new to this so please take it easy. I need to come up with something to convert a 5V digital output signal from a USB-1608G DAQ device with DIO to 24V ...
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Make a single bit memory using transistor

I want to make a single bit memory using transistors. And if can, I want its data is still stored. Thank you! I am very sory that English isn't my mother language. Sorry for any mistake.
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129 views

How can I determine the collector voltage of Q1 in this circuit?

How can I determine the collector voltage of Q1 in this circuit? I suppose it is very simple but it really puzzled me. Thanks all.
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696 views

BJT DC Leakage (ICES) dependency with Vce

I am interested in BJT transistor leakage dependency on Vce. Specifically: parameter ICES (Collector-Emitter Cutoff Leakage, that is, collector/emitter leakage with base shorted to emitter) is ...
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84 views

SMD transistor die vs DIP transistor die

Is the die of SMD transistors different from die of DIP transistors with a unique part number? Is the power transmission of a transistor dependent on its package type or chip type ?
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176 views

Calculating gate to source voltages in h-bridge circuit

The circuit shown above is an h-bridge circuit. It works by letting a microcontroller send a low/high signal on R1 or R4. I've been told to determine all the Gate to source voltages for each of the ...
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Class A amplifier - Transistor Q-Point calculation

Reference: http://www.learningaboutelectronics.com/Articles/How-to-find-the-q-point-of-a-transistor-circuit I am trying to understand this q-point calculation. I recently asked a question about the ...
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146 views

PNP base transistor

So I am making a small digital clock using a grid of LEDs and multiplexing. My question is, when testing my grid, the pnp transistors would turn on only when there was a resistor between base and ...
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49 views

What is the forward beta of the BJT KN2222A?

I don't know what is the forward beta of the bipolar junction transistor KN2222A, I'm an amateur and i don't found the value in the data sheet or i just don't understand where. Please let me know
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1answer
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What mosfet do I use in induction heater?

I have been building an induction heater based off this schematic. I have tried using irfp250m mosfets. Works like a charm. But whenever I put a too big piece of iron inside the coil, the mosfets soon ...
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69 views

Can you connect transistors directly to high voltages or is there precautions neccesary?

I understand that the circuit above will simply work, but what if the voltage input from the battery is significantly higher and the necessary voltage for the motor is high as well? Can you still ...
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Why do TTL integrated circuits have such complicated schematics for logic gates with so many transistors as opposed to RTL?

I'm in the process of building a 4 bit computer out of discrete NPN BJTs and resistors. I'm using RTL, and I've made flip flops, full adders, and demultiplexers, and everything is working fine so far. ...
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34 views

stepper motor torque control

I am trying to make a sim racing wheel with force feedback using a closed loop stepper motor. I need to have variable torque applied to the wheel. If i use a transistor with a microcontroller to ...
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158 views

Why isn't my transistor saturated?

Using a BC546 NPN Transistor to trigger an SSR from a current sensor. Sensor to give 1.5-2.7 V out to drive the transistor. SSR requires >= 3 V and uses up to 10 mA. I want the transistor to fully ...
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69 views

MOSFET switching on

I have a doubt. Consider an N-MOSFET: which is the voltage that can switch on it? The voltage between Gate and? Sometimes I read "between Gate and Bulk", sometimes "between Gate and Source", sometimes ...
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37 views

RC timer not reaching desired voltage

I'm trying to make a circuit that will light the led with progressive intensity one second after the circuit is powered. For that I created an RC net with tau equal to 1 sec. At 1 second I expect the ...
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138 views

DC and AC analysis of a Common Emitter Amplifier Circuit

What we know about the circuit is that in DC-analysis (when \$V_{in}=0\$), \$V_{out}=10V\$. We also know that the circuit (even outside of DC analysis) will have \$I_{C}=2mA\$ and \$V_{CE}=5V\$. \$R_{...
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47 views

Bypassing battery cell with transistors

Is it possible to create the schematic below with transistors in any way? As I see it, there is no voltage difference between j1 & j2, so a transistor connected the normal way would not work. ...
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39 views

Bipolar Transistor's Input Resistance

Based on theory when you want to find the output resistance of a circuit with dependent sources you can't turn them off so you have to add another source of known value in the points of interest and ...
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107 views

Help identifying SMD components

I am having trouble identifying some components in this circuit. I am not sure if these are commercially available or not, so that's why I am asking. The components are shown below: I believe this ...
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Can the base voltage (say 5V) be lower than the collector voltage (say 12V)?

I am new to electronics so sorry if this question sounds stupid. I want to control a 2N222 transistor (the normal gain kinda way) and wanted to ask if the base voltage can be lower than the collector ...
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42 views

NMOS to NPN Circuit Analysis

I am attempting to us a voltage shut off switch with some pre-existing hardware. I do not understand transistors well enough yet and am looking for clarification. I desire for V2 to be able to go to ...
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1answer
142 views

Solenoid switched by TIP120 transistor stopped working after two weeks

I have no kind of knowledge about these things. I just copied some instructions from different projects and now my project died. I have this 12V 0.8A solenoid that switched for about two weeks. Now ...
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163 views

i need to control rgb leds brightness using phototransistor plus transistor and at the same time send light value to analog pin on Arduino

Schematic is missing led resistor. i need to control rgb leds brightness using phototransistor plus transistor and at the same time send light value to analog pin on .I'm not sure where do I go from ...
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60 views

Two state switch using transistor (bi-directional)

I have an existing pair of wires driving a servo motor. One of them is +12V, the other one 0V. Depending on the rotation direction of the motor, the voltage flips. I now want to put an optional ...
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1answer
28 views

Plotting G(t) of an oscillator in Cadence

I have a cross-coupled NMOS-only oscillator that has its bias voltage changing so its transconductance is also changing over time. I want to plot its transconductance (G(t)=G0-gm/2) over time in ...
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142 views

Arduino LED 9 V transistor with a common ground

simulate this circuit – Schematic created using CircuitLab I am kind of new to building my own electronics. I am building a stargate with 3D printed parts. When I soldered all the LEDs ...
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Identification of bipolar transistors on die (pnp or npn?)

is it possible to tell from this photograph whether the transistors are npn or pnp? And if so, what is the line of reasoning? How to sort that out? This photo I took is from a Sharp GP1FAV51RK0F ...
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Mosfet and diode circuit

UDD = 1,8 V Uth = 0,7 V R1 = 300 Ohm KM1 = 25mAV^-2 UD = 0,7 V UG = 1,8 V I should calculate Ron and I did that: Ron = 1 / (KM1 * (UGS - Uth)) = 36.36 Ohm Is that right?
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56 views

Enabling/disabling a pull-up with a microcontroller (and a level shifter)

(Split up from this question) I'm trying to interface an Arduino with an eMMC chip to bit-bang it. eMMC uses bidirectional lines, and one of them (CMD) is first used in open-drain mode (for ...