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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Microcontroller output configuration
Hello,
above screenshot depicts output configuration in one of STM32 microcontroller. I would like to examine it a bit to understand what is going on and what I can expect.
First of all the manual ...
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How to start micro controller using transistor
I have a RCWL-0516 doppler radar microwave motion sensor module which I want to start using a on/off wireless controller.
When the wireless controller is on, it outputs a 3V continuous signal, while ...
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What is a self biasing of a transistor. Explain with a circuit of it
There was a question in my semester exam. "Define stability factor. Explain self-bias circuit with diagram and derive expression for stability factor."
Now after searching a bit I found that when the ...
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Mixed NPN and PNP H-Bridge DC Motor Driver
I've briefly looked at including an H-Bridge circuit in one of my designs and I see that most (if not all) have N-Type transistors (either Darlington
or MosFets). This however needs two separate ...
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Transistor saturation current
From the above I/V characteristic we can conclude (and this is what books say) that during saturation collector current is very limited and tends to zero. How is that possible if during such condition ...
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Photo resistor night light not working
I am completely new to this stack exchange and to electronics and general so please keep that in mind if my question is not up to par for this site.
I've attempted to make a night light using a ...
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How do surface mount components withstand heat of reflow while through hole components can not?
I have read some online tutorials about soldering through hole components which say that transistors and ICs are delicate components and can be easily damaged by heat. So they recommend to keep the ...
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Current and P-N channel MOSFET
I'm new to electronics, and I have a question.
Let's imagine you have something in parallel that drives in total 100 mA.
To turn it on and off you use a pin from your microcontroller, but the pin can ...
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Why did a 1k resistor at the MOSFET gate solve my problem?
Why did a 1k resistor solve my problem?
I wanted to control a 3 wire computer fan with PWM(25 kHz 50% duty) from my Arduino NANO pin 10. My Circuit was very simple. I had an IRLB8721F N-Channel ...
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Switching a 20mA LED with 4mA output of same voltage
I have a USB controller card with output pins of 3.3V and a maximum current draw of 4mA per pin, and I'm trying to use it to control 3.3V 20mA LED's.
I figured I'd need to use probably an NPN ...
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Purpose of a two-transistor circuit
The following transistor circuit appears in the schematic for the Apple II disk controller card.
I don't understand the purpose of this subcircuit. I think it must have something to do with ...
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Can I use BC558 PNP transistor with 5V DC supply?
How will I know what is the VCC voltage range required so that transistor can work? I was checking the datasheet and couldn't understand much on it. My requirement is that I have got 5V DC supply. I ...
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Transistor amplification
for the below circuit I don't quite understand why the output voltage is negative.
In the book I read they say:
\$\ V_{out} = -K R_{L}V_{in}\$
So, why negative sign? Book says "The negative sign ...
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Using a single power source for both the gate and source of my transistor?
I am using an IRFZ44N MOSFET (n-type) transistor to regulate the current of a Lithium-ion battery, and I'm trying to use the battery to supply power to both the drain and gate of the transistor. My ...
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How switch a 3v load high side, from a uC powered from same 3v?
I have a uC (Arduino Mini) powered from 2xAA battery pack.
The Mini display some data on a circuit with a MAX7219 + 2x7segments 4 digits led (a total of 8 numbers).
Because it is powered from battery ...
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op amp circuit functionality
what is the functionality of following circuit?
It's a LM324 opamp and a sin or ramp signal get into it's inverting input and non-inverting input grounded. It's power is 12 and -12 and output of op ...
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Transistor Oscillator Simulation Convergence
For the circuit in the figure (both in Altium Designer 16, and Proteus 8), by using the standard NPN Spice model, I had a really hard time trying to make the simulation converge.
I tried Trapezoidal, ...
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Interrupt circuit
I'm using an 'Arduino like' board with a PIR sensor that gives 3.3V when movement is detected.
The board usually stays in sleep mode, and wakes up when a LOW value is given to a specific pin.
What'...
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1
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Very high frequency FET
I am trying to amplify a very high frequency square wave. The waveform is 3.3Vpp (biased so it's going from 0 to 3.3v), around 145MHz. I'd like to amplify it to around 10Vpp (doesn't matter if it's ...
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Amplify a signal having a DC component without using an opamp
I am building a simple modular synthesizer. I would like to keep everything simple and prefer to use discrete components over integrated circuits. My goal is to improve my knowledge about electronics.
...
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How to BJT NPN switch 12v using 5v with common ground?
I want to build the AVR High-Voltage programmer, it requires the RESET pin to source 12 volts while the rest of the AVR is powered by 5 volts. The ground for 12 ...
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How does Shift+Turn off disable the circuit of the calculator?
How does it electronically work that in a basic Casio calculator, shift+ ac turns off calculator, is it a comparator that compares these two button states then triggers a transistor?
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Transistors on op-amp power rails
What is the advantage of using transistors on the power rails of an op-amp over more typical boost circuits?
I have seen a circuit topology called the "Widlar Boost" made famous by Bob ...
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Why is my MOSFET switch circut not working?
Using the falstad.com circut designer I found a simple mosfet switching circut. However, upon constructing it in real life I found that:
~after powering it on the led starts glowing dimly (it should ...
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Protecting against reverse polarity
I'm building a JTAG programmer for the old Motorola 56k devices and I want to add some circuit protection before having some boards built. I'm more of a firmware/digital guy, but here's what I came up ...
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Use of transistor for switching the led
I have been trying a lot to get my circuit work. I want the led to light up when the LDR receives no light and vice versa. I have found that the LDR offers the resistance of approximately 6k ohms when ...
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Need a bit of guidance in regards to this PNP transistor question
simulate this circuit – Schematic created using CircuitLab
Hello!
I'm currently stuck trying to answer this question. The question asks for me to find the resistance of R2 for R1 to be at 4V ...
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Getting an OR latch to work in a circuit
I have a 74hc32 that feeds back the output from an or gate into its input. The independent input comes from a comparator that outputs high when the photoresistor voltage is greater than the referenced ...
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BJT base connected to ground and still operates?
When in university I used to get confused how a transistor (NPN) can draw current from ground. I'm now studying power amplifiers and again, this same configuration appears. How does Ir draw current ...
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How and why does this oscillator work?
I am a beginner hobbyist, trying to understand a circuit from an old Radio Shack electronic snap kits game (the game variant I have is "electronics 303", and the circuit is project #202 : ...
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MOSFET always slightly on (with Pulldown) and other strange behaviour [duplicate]
I'm trying to control my RGB LED strip with my arduino, using IRLZ34N MOSFETs according to this schematic
simulate this circuit – Schematic created using CircuitLab
I tried it out, everything ...
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MOSFET always slightly on and other strange behaviour
I'm trying to control my RGB LED strip with my arduino, using IRLZ34N MOSFETs according to this schematic
simulate this circuit – Schematic created using CircuitLab
I tried it out, everything ...
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Transistor action, transistor as an amplifier
On Using the transistor as amplifier, does the Current Gain stay constant by changing base current or R base?
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Why is my 2n3904 amp bass-boosting?
simulate this circuit – Schematic created using CircuitLab
Hello!
I have constructed my very first amplifier with 2n3904 transistor, based on the diagram and suggestions from comments from ...
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Finding node voltages of transistor
I have the following problem, it consists of BJTs connected in the following way. I am being asked to find the node voltages. Am doing the part were beta=100 and R is connected.
I have done the work ...
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Fixing the amplifier in an old arcade machine
I'm trying to fix the amplifier in my Chicago Coin Speedway arcade machine.
It works but it has a bad hum in it. I replaced a couple capacitors that were in bad shape but the hum is still there.
I ...
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How is this simple circuit working?
I'm trying to understand why this simple circuit below works the way does: As it gets darker over the photoresistor (RP) the LED gets brighter.
I'm trying to understand it by following the path the ...
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How does the NPN transistor in a 555 timer discharge the capacitor when the output is low?
I am new to electronics and I'm trying to understand how the 555 timer works based on the diagram below. I am following the tutorial/explanation at https://www.electronics-tutorials.ws/waveforms/...
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Selecting a switching transistor for a 5V relay
I would like to use a STM32F microcontroller with 3.3V digital io pins which can deliver a max of 22mA to switch a transistor to then power a 5V relay which pulls 28mA. I'm not entirely sure what ...
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What's the purpose of these two diodes in this circuit?
What's to point of using these two diodes? Can't you just replace them with a resistor?
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Resetting 555 via Transistor (optionally driven by Touchplate/Piezo)
Right now I am using a 555 circuit to generate a 1kHz square oscillation (not displayed below). Generally the reset is pulled down, but through a button I drive a transistor to output the square ...
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Is the hybrid-pi parameter hie really equivalent to (beta+1)*re?
I'm reading a book on feedback amplifiers at the moment and it makes comprehensive use of a simplified hybrid-pi model. A parameter that keeps popping up is hie and I've always considered this to be ...
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Are these resistors in series?
We had this question as a part of a small signal analysis question on the Final. This circuit I drew below is the DC analysis which is the first step pre-AC analysis which will have a totally ...
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Transistor count of floating point multiplier
I'm trying to figure out just how expensive floating point fundamentally is, at the hardware level. For example, how many more transistors does a 32-bit multiplier cost in floating point compared to ...
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How to make the output of a transistor the same as the input?
I'm new to circuits in general but have a basic understanding of it. However, it seems I can't wrap my head around the following issue:
(I'm using Tinkercad Circuits for trying out different ...
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Using a transistor to control a pull-down switch
simulate this circuit – Schematic created using CircuitLab
I have a Runcam 2 video camera. It uses a temporary switch to turn on/off and start/stop recording. I would like to control these ...
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Identifying parts of a transistor die
In books, I have studied that in a Transistor, the Base is the layer sandwiched in between Collector an Emitter. Wikipedia also mentions that
"The base is physically located between the emitter ...
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Why can't class A amp drive 8 ohm speaker with just one BJT?
I designed this class A amplifier. It's my first attempt at designing an amplifier with transistors. My objective is to build a guitar amplifier with tubes, but I figured that building an amp with ...
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Power Supply 9v
Hi i am building a power supply for a project and the specifications are to build my own voltage regulator.
The power supply consists of converting 120V AC to 9V DC with 100mA of current and minimum ...
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Why is D2 switched off and T4 not in saturation mode in 7408 TTL Gate as shown below?
In the circuit, when both the inputs are high at 5V, than why is D2 switched off? Will it not draw voltage from Vcc?
Also, when one of the input is low, why is T4 not running in saturation mode? Will ...