Questions tagged [transistors]
A transistor is a semiconductor device that can amplify signals and switch power. The types that are used most are BJT (Bipolar Junction Transistor), UJT (Unijunction Transistor), and MOSFET (FET, for Field Effect Transistor).
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Increasing power of a Standalone Circuit Board
-Picture at bottom of post-
I am a rookie at potentially upgrading some electronics and wanted to see if I could get a little direction on a potential first project. I purchased a small frequency ...
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Dynamic Logic - Transistor Sizing
If we have a circuit in dynamic logic:
What should the size of the charge transistors (Qe and Qp) be? I know that increasing the size improves the speed but also increases the dissipation, and that ...
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Reducing the fall-time of a P-channel MOSFET Follow-up
The original question
Answer by Simon Fitch
Please refer the original question link and the suggested answer by Simon fitch
I have implemented in hardware as it was recommended. I gave 15Vdc supply. ...
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Why are the current-voltage characteristics of a bipolar transistor in MATLAB and LTspice different?
I simulated the 2N5089 bipolar transistor in both programs. The output I-V curve is completely different, although both programs use the Ebers-Moll model.
Spice-model of the transistor:
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Why does the frequency of an astable multivibrator depend strongly on the supply voltage?
More specifically, my question is why does the natural frequency of the canonical (basic) symmetric transistor astable multivibrator (STAM) vary so strongly on the power supply voltage? As a follow-...
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Which one would be better for 3.3V outputs among ULN2001 and ULN2003?
I intend on driving 24VDC relays with darlington arrays of the ULN200X series. Since the darlingtons will be driven by a 3.3VDC outputs I am hesitating on whether I should choose ULN2003 or ULN2001.
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Reducing the fall-time of a P-channel MOSFET
I have implemented the following circuit in hardware.
My required output across load (R7) is a pulsed signal of 20 V, 100 kHz, 10% duty cycle (10 us pulse width and ON-time of 1us and OFF-time of 9 us)...
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Question on testing transistor TIP120 NPN using multimeter
Could someone please help to confirm if these values for a TIP120 NPN transistor based on the diode setting of my multimeter, indicate any potential fault?
Base (Positive) with Emitter (Negative): 0....
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Transistor in pull-down "switch" application
What is the transistor circuit which acts as a SPST switch given: 1) +24vdc, 2) ground, 3) a "floating" pin that the switch takes to ground when triggered (there is no "load")? I ...
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What determines an electret microphone voltage?
I am trying to get an electret microphone working with my Raspberry Pi Pico's ADC pin. I am trying to detect the output by passing it through a transistor.
I have a 4.5V voltage source. I split this ...
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Level Shifter design. 0-10vdc to 0-24vdc using pnp transistor
I have 2n3906 transistor. I want 24vdc output when 0vdc and 0vdc output when 10vdc. I want to give this output to plc which has 2.5mA min current requirement for logic high. I have 24vdc rail ...
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Diode and bipolar NPN transistors orientation not correct, says JLCPCB
JLCPCB is telling me 4 components are incorrect but when I look over it and the datasheet it all seems correct to me.
My original | JLCPCB corrected:
This is what my current board looks like:
My ...
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Low Drain-Source MOSFET Leakage
I've been looking at the SM74611 Smart Bypass Diode from Texas Instruments and am very impressed with the reported reverse leakage current (0.3uA at 25C). Considering the device has a N-Channel FET, ...
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How to receive input signal on Raspberry Pi GPIO from transistor emitter
I'm trying to build a simple circuit that allows a Raspberry Pi to detect AC voltage in a piece of wire inductively.
I have the following circuit which basically uses an antenna wrapped around the ...
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What does "gate potential" mean?
I was given this problem to solve:
"Calculate R1, R3 and R4 so that the FET-transistor get the operating point I_DQ = 3mA, U_DSQ = 3V and the gate potential +2V. The Value of R2 is 16kOhms and ...
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best 5v switch with 3.3v
i have a kobo with a serial port output providing 3.3v when the device is turned on.
i want to use it to control a microcontroller 5v board with esp32 on it drawing max 200mA directly from the battery ...
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What is the design reason behind these components?
I have some questions regarding the comparison of these two circuits. Both produce current noise through the first reverse-biased transistor. That variable current enters through the base of the ...
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How to estimate the voltage gain, Input impedance, current gain, power gain, and output impedance for the amplifier in the fig?
β of the BJT is 100 and from dc analysis it is found that the quiescent point is ICQ=4.12mA and VCE = 6.72V.
If the emitter resistor RE is subdivided into RE1=100 Ω and RE2=900 Ω, with bypass ...
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Sizing an CMOS StrongArm Latch comparator on Virtuoso from scratch
I'm currently designing an CMOS comparator and I'm a little bit lost regarding sizing the transistors. I was taught to use the Id formula, but for that to work I need to have muCox, and I do not. Can'...
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Taylor expansion relationship with transistor conductivity [closed]
Write an equation that represents the base-emitter voltage change and the collector current change of a bipolar transistor, assuming that the base-emitter voltage has a DC component and an AC ...
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Common base configuration
I have tried to implement this circuit of common base configuration but the power supply used in the lab is very confusing and I suspect it’s the reason why my readings aren’t turning out right (it’s ...
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How does a common gate MOSFET turn on if the gate is grounded? [closed]
For a NMOS to turn on the Gate to Source potential diff has to be greater than the threshold voltage. But if the gate is grounded like shown in M1 below how could the MOSFET ever be turned ON (or how ...
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Resistor values for a voltage-controlled current source circuit
simulate this circuit – Schematic created using CircuitLab
During my bachelor thesis, I am learning IGBT gate driver circuits. I am struggling with understanding the following circuit. It is a ...
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How to use TM1637 on a PNP driven 7 segment display
I am trying to get this 20-year-old board working again for a few days now, constantly feeling I am close to the solution, but I can't get it to work.
The segments Led[3..5] are wired to connector P3 ...
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Circuit for high-voltage pulses using Raspberry Pi PWM to drive a piezoelectric actuator
I am trying to engineer a device to separate red blood cells from blood plasma in 100mm x 1mm capillary tubes using the Raspberry Pi GPIO pin PWM feature and a piezoelectric actuator.
The pulses ...
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How dome lights can burn out the transistors of PCB? [closed]
Dome lights doesn't work and found out transistors of pcb are burned out. Why this happened?
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Transistor works with just base connected
Currently I am trying to self learn electronics. After the diode I moved to the transistor.
I understood the transistor as an “electronic” switch with no moving parts. When the base is connected, then ...
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How do I select and use a BJT in a simple LED circuit? [closed]
I am trying to understand how to use a transistor in a simple LED circuit.
The LED (blue) has a forward voltage of 3V, and I'd like to provide it with 19-20mA. VCC on the circuit is 3.3V. I was ...
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The condition of linear operation of the transistor Dipole in small signal mode
How small should the base-emitter voltage changes of the transistor be so that the relationship between the base-emitter voltage changes and the collector current changes can be considered linear?
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NC switch circuit with transistor
I want to create a NC switch in my electrical circuit to take power away from the 3.7 V internal battery when 5 V is received on a micro-USB for charging. By 0 V I mean No Connection or a mV, not GND.
...
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Understanding a 2 transistor oscillator?
I asked a question here about why I was getting a sawtooth wave from a two transistor oscillator. While that question is answered, I don't understand how the circuit produces oscillation in the first ...
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NPN Transistor Base Current Calculation from Beta, Vth, and Rth
In this answered question regarding a common emitter NPN Transistor....
NPN Transistor common emitter calculation
I am struggling to understand the section "Assuming Active Mode"
...
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MOSFET transistor replacement for Proform T7 Treadmill
Treadmill motor turns for a second and immediately stops. After researching issue, looks to be a blown IRFP250M
IOR P039J 20 8J.
My question is, I'm having trouble finding a replacement that includes ...
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SR flip flip memory cell
simulate this circuit – Schematic created using CircuitLab
I implement following circuit as SR flip flop memory cell.
It seems that both PNP transistor are turned on, and MOSFET-N can not turn ...
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Inconsistent resistance measurement in H-bridge
I have an H-bridge circuit that is meant to measure the voltage across the shunt (330 resistor) and load (pictured as 4700, but variable) to calculate the resistance of the load (I have added the 10k ...
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Astable Multivibrator Not Oscillating
I've been trying to get the Astable Multivibrator Circuit to work for a long time now, and I think I lack the knowledge to understand what's going on here.
The situation is as follows: I've checked ...
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What is the "collector light current" of a phototransistor and how does it relate to the collector current?
I found the "collector light current" term in this datasheet (Vishay TEFT4300) but I can't find a definition for it on the internet nor figure out how it relates to the collector current.
I ...
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How to determine the collector current limiting resistors for the Darlington's pair of transistors?
How were the resistors in the circuit calculated?, I would like to come up with a similar circuit but for a 5VDC power supply, and I would like to resize the resistors as per my load requirement, my ...
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Dual N/P-Channel MOSFET Dies with Smoke
I have built the following N-MOS & P-MOS push-pull dual MOSFET circuit. Its purpose is to control some external LEDs from a 3.3V microprocessor.
However, there seems to be a problem, where the ...
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Am I using these MOSFETs correctly?
I am designing and testing a circuit that charges a capacitor to around 50V using a boost converter when 'ARM' is high, then discharges it through a solenoid when 'FIRE' is high. ARM and FIRE are ...
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Three stage amplifier with third transistor connected to emitter of second
My question is that for voltage gain, is it correct if I take voltage gain of each transistor and then multiplying, to get gain of whole circuit?
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Computations for Capacitors in a Class AB Power Amplifier
How do you compute the appropriate values for the input and output coupling capacitors (C1, C2, C3) in this design of a Class AB power amp circuit? Are there any formulas?
If the formula involves the ...
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Water level indicator LEDs one by one
I want to make a water level indicator but, instead of all LEDs lighting at 100% (for example) I want the top one only to light and the rest turn off
at 0% all LEDs off
at 25% the first LED on
at 50% ...
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How can I calculate the current induced in the copper coil that is wrapped around a single phase of an 11kV, 2616A distribution line?
Aim: To develop an alert system for power outages in the distribution line, informing electricians of their occurrence.
Working Principal:
Fuse Monitoring: The Arduino measures the status of the power ...
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How to control unrelated circuit with a transistor?
I recently hit this issue that seems to be too complicated for google to find results for.
Is it possible to control a different circuit with a transistor from a separate circuit?
Below is a ...
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SMD SOT-23-3 device identification - top marking E8LJ0
I have a small SOT-23 (3 pins, transistor-like) device that burned out (shorted between 2 pins). I need to identify it so I can replace it, but I can't find the code at all. The code is: E8LJ0
Thank ...
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Will the gate driver circuit of MOSFET work?
I have implemented this circuit in the hardware. The desired pulse output across 2 Ω is 28 V output, minimum 10 A output current with 100 kHz frequency and 10% duty cycle. The drain pulse is not ...
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How to make an LED light when motor stops running?
How can I make the LED light when the motor stops running (aka the output from the op amp (pencil drawn) is low and so the transistor base input is low)?
In this configuration. My LED lights when the ...
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Why NPN Transistor AND Gate not working?
I am trying to form an AND Gate using 2 NPN Transistors, But the led lights up when i turn on the right switch and the left switch doesn't make any change, Can Someone please point out the problem,
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Correct circuit design to light an LED
I'm wondering if anyone sees an issue with this circuit. Basically using a button to control the Output Enable (OE) signal to a 74HC245 running at 3.3V. When the button is not pressed, the OE is not ...
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