Questions tagged [npn]
A type of bipolar transistor comprised of n-type semiconductor in contact with p-type semiconductor which in turn is in contact with a n-type semiconductor -> thus NPN. The transistor has three terminals, the Emitter, Base and the Collector. Current injected into the base controls the flow of current from Emitter to Collector enabling amplification and switching.
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The resistor is over heated in my totem pole circuit
This is my totem pole circuit:
It works well, but R32 is too hot.
This is scope:
I changed R32, R34to 470 ohm, but I got the same result:
I think the resistor value is the problem. How can I fix ...
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How can I turn off the 555 IC using MCU GPIO?
This is a simple circuit: PWM motor controller circuit using switch potentiometer
I want to turn the 555 IC on/off. But it didn't work.
How can I fix it?
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Single-NPN driver for an N-channel MOSFET
After years of neglect, I have just got back on track in my journey of learning electricity and electronics, and I am now considering the building of multiple projects to which MOSFET gate driver ...
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Simple circuit works with BC547, but not with 2N3904
I am following a very simple schematic which is a NOT gate with a push button as input. The output is used to drive the base of a second transistor that turns on an LED:
This circuit works perfectly ...
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Why does this NPN transistor conduct current when base is connected to ground?
I have been working on designing a board that contains a seven-segment LED display with red and green LEDs driven by PNP and NPN transistors. The red and green LEDs have different voltages but are ...
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Delay ON signal from sensor (NPN)
I have sensor (slotted IR optocoupler) that has IR diode and IR detector (transistor), where emitter is connected to ground. On device side I have connector with 3 pins - Vcc, GND and signal line, ...
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Is the emitter-base diode forward biased when an NPN transistor is used as an amplifier?
I came across a question asking about the state of both the emitter-base \$EB\$ and collector-base \$CB\$ diodes when an NPN transistor is used in amplification.
My understanding is that for ...
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I am trying to figure out why npn does not work here... what assumptions should be made?
So I tried the calculation of
ic = (15-10)/2k = 2.5mA -> ib = 25uA, ie = 2.525mA
Vce = 15 - 2k*(2.5mA+2.525mA) = 4.95V
As Vbe = 0.5V, Vb = 5.55V required
voltage drop by 10k resistor = 250mV -> ...
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How can I control PNP and NPN transistors together from one pin?
I'm trying to understand how it is possible to control a PNP and a NPN transistor simultaneously from one controlling pin.
My issue is that when the INPUT pin is left floating, the transistors drive ...
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Beta, voltage, current and resistor of 2 NPN BJT connected to each other
We were asked to get the β’ (the β of the single BJT equivalent), VB’E’on (the voltage from B’ to E’ when conducting),VC’E’sat (the minimum voltage that can exist between C’ and E’), Isat (max ...
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Raspberry Pi Pico GPIO amplification
I'm trying to control a handful of LEDs via Raspberry Pi Pico, on a single GPIO pin.
I've wired up 14 LEDs in parallel, each with it's own resistor (330 Ohm, .5 Watt). Combined, the LEDs need to pull ...
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FET driving by NPN issue (PWM)
I am having a few problems regarding a simple FET PWM driver. I am aware this circuit does not adhere to the best design practice, but I am in a situation where the design cannot be changed.
I have ...
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2SB772 PNP SPICE model [closed]
I have trouble finding 2SB772 SPICE model. Can anyone help?
I can provide its complement NPN 2SD882 SPICE model
.model Q2sd882 NPN(Is=282f Xti=3 Eg=1.11 Vaf=100 Bf=200.7 Ise=288.7f Ne=1.368 Ikf=20 Nk=...
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How can I protect my printer's motherboard from a failing NPN inductive probe?
I am wiring up my new 3D printer motherboard. I am using a lj12a3-4-z\bx inductive proximity sensor for my bed sensing probe. In order for the probe to function at ...
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How different structure (Resistor, Diode, and Transistor) can be model in IC?
I found this image in the book "Practical Electronics for Inventor".
I can partially understand what is happening in diode, and transistor. But how does the resistor works?
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For this NPN current source circuit, why is the simulator indicating such a high base current?
simulate this circuit – Schematic created using CircuitLab
Why is the base current into Q1 so high according to the simulator? It is higher than I expect.
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LED still on when transistor is closed with Arduino
When simulating the following circuit, there is no problem. However, when I do it in real life, with a BC558 transistor, the LED stays on even when the Arduino is not sending any voltage.
The resistor ...
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To BJT or not to BJT: That is the question [duplicate]
Practically speaking, when is it better to use a BJT vs a FET for swtiching (not as a linear amp)?
Given that FETs have both N-channel and P-channel forms, and BJTs come in NPN or PNP, it seems that ...
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Need help driving the enable pin on a TPS2595 with a voltage divider; not exactly sure which method is better to use
I'm a hobbyist at best, and am trying to overcome the learning curve as far as pull-up and pull-down resistors, N channel transistors and P channel transistors, etc, etc.
I've got a USB Type-C charge ...
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Switching 9V using a NPN transistor and 5V alarm output
I am needing to trigger a relay with the alarm output of a fluke DAQ. The alarm is only outputting 5V 0.15mA which is not enough current to trigger the relay I am using, a Data Loggers IoT Relay II.
I ...
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Maximum voltage range for input in emitter follower
In Horowitz - Hill's The Art of Electronics, 2nd edition, paragraph 2.03, an emitter follower with an npn BJT is presented. Figure 2.8 uses a symmetrical power supply:
simulate this circuit – ...
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I have a schematic where the bases of two transistors are connected with each other. I don't understand how it is supposed to perform any function
I'm reverse engineering a MPPT charge controller. I looked at its PCB and I drew the schematic from it and I've been as thorough as I can (checking and cross-checking many times).
I know the "...
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Can someone explain this circuit to me? I'm especially confused about how the transistors work with their bases connected to each other
This circuit is from this video.
I'm confused about how the transistors work in this circuit.
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Why is base current needed after transistor is switched on?
If there already is a current flowing from the collector to the emitter, can’t the electrons just keep jumping over the PN junction?
Why does killing the base current make that impossible?
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The motor barely spins in this H-Bridge circuit?
The motor barely spins in this H-Bridge circuit.
So I put together this schematic with 4x Tip41c NPN transistors. I also tried tip120 NPN.
The resistors were 1k ohms.
Running off the RaspberryPi 3.3V ...
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Can I use a CA3081 NPN transistor array instead of a bunch of 2N3904 transistors to drive a bunch of MOSFETs?
I was going to drive a MOSFET from an ESP32 (3.3 V output) with a 2N3904 NPN transistor like this:
I will need 24 MOSFETs in my project, and that is a lot of soldering.
I found the CA3081 general ...
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C1815 NPN transistor output voltage doesn't exceed 5 V
The connections are as follows:
[+5 V from arduino pin] => 680 Ω resistor => C1815 transistor's base pin (3)
[+14 V from variable power supply] => C1815 transistor's collector pin (2)
[C1815 ...
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How do I saturate an NPN transistor for switching?
I want to use a 12F675 to turn on two LEDs. After a little research, I decided to use a 2N2222A NPN transistor and 2 LEDs in series (2V-drop 20mA consumption.)
As I read in datasheet, microcontroller ...
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NPN transistor not emitting anticipated voltage [closed]
I have 12 V connected to the collector of an NPN transistor. I have a pin of an ESP8255 (which emits 3.3 V) connected to the base. I'm trying to power a 7-segment display with it, but the emitter ...
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Creating a 3.3 V audio amplifier using an NPN 2N2222 transistor
It has been way too long since I did anything with transistor amplifiers. I am trying to find an example of a 3.3 V NPN transistor amplifier preferably based around a 2N2222 transistor. I have lost ...
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NPN BJT on voltage
I'm in the process of designing this small circuit using an SS8050 NPN transistor.
I have an input base voltage of 1.28V and I'd like it to be working as a switch to turn on a little buzzer.
According ...
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Unexpected voltages on home-made OR gate
I've created some home-made gates using discreet components onto strip board.
So far I have an OR gates, an AND gate and 4 NOR gates.
Logically they all work as expected but on only one of my 4 NOR ...
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NPN transistor seems on even though base is grounded with resistor
I have this very simple circuit, which behaves strangely. OC0A is a ~64kHz/50% PWM signal coming from an ATmega328P.
With the circuit as pictured, the LED lights up EXTREMELY dim even though R2 ...
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How do I create this circuit using NPN instead of PNP transistors
Due to reasons and curiosity, I want to know if I can recreate this circuit using NPN transistors instead of PNP transistors. I know functionally that they can be the same if we invert the polarities; ...
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Layperson asking intuitive question about bipolar junction transistor
I am a layperson trying to understand how the bipolar junction transistor works from this excellent article: https://spectrum.ieee.org/transistor-history
The relevant paragraphs are as follows:
...
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NPN transistors, LED strip and Arduino
I'm trying to control an LED-strip with an Arduino like an 8x8 matrix with a common anode (pic 1).
I put 2 NPN-transistors in the circuit and a LED-strip between them. The first transistors in pic 2 ...
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What is the purpose of these transistor pairs
This picture is part of a circuit designed to measure capacitance. The control circuit would apply +12V or -12V on "DTR pin 20" and the two resistors give a minimum and maximum voltage ...
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Operating point for high current transistors
I'm a neophyte self-thaught learning electronics. I'm trying to amplify a DC current from a little less than 1 to 8 A using an NPN transistor. Currently I'm trying to figure out how even could I ...
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ESP32 opto-isolated relay board not working - PC817 opto-isolator, 2N3904 NPN BJT and SRD-05VDC-SL-C relay
I have just finished soldering my "custom designed" ESP32 PCB board that I'd like to use for management of 6 x 24 Vac irrigation valves.
Given my limited electronics knowledge, for ...
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Voltage measured across transistor and transistor base current don't match calculated values
This is a newbie question regarding my second electrical circuit. I've built a switch on a breadboard using NPN transistor SS8050 and it works though voltage across transistor's collector and emitter ...
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What are junctions in a transistor and how does current flow in them?
I want to clarify what "junctions" are in an NPN transistor and how current flows in them.
Is the area inside the blue circle considered the "BC" junction?
According to wikipedia ...
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Clarifying how a NPN transistor can act as a switch with a LED in a circuit
I'm experimenting with a simple transistor/LED circuit but after reading many articles online I still can't tell if I have a faulty transistor or things are working as expected.
Power source = 5V DC ...
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Can an NPN transistor have its base connected to the same power input as the collector?
All the tutorials I have seen on using an NPN transistor as a switch have base and collector attached to two different power inputs with two different resistors:
My question is, can the base just be ...
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High-voltage (48 V typ.) switching circuit
I am working on a design where the input (48 VDC) has to be supplied to I/O when a particular condition is met and the rest of the time it should be grounded.
A relay is ideal for this, but the PCB ...
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What are the invisible reasons why many discrete transistors do not qualify for automotive use?
I looked today at the datasheets of
this unqualified
and
this qualified
product (per the AEC-Q101 automotive standard) and found no substantial difference, but I assume some stress damages only the ...
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NPN transistor small output voltage
I just learned about measuring the base resistor of a transistor but I think I did something wrong.
I wired everything up like this, but when I measure it I only get around 2.7V out of my device. Is ...
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Time delay of LED dimmer circuit problem
I made a LED flip flop circuit using NPN transistor, it works pretty fine.
But my problem now is I don't know how to control the on and off time delay for the LEDs using potentiometer.
I tried putting ...
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How does T3 turn on?
This is a part of a well known product created by Markus Frejek and now maintained by Karl-Heinz Kübbeler (more info). It is the famous "transistor tester" or "component tester" (...
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Use of MOSFET or BJT
I'm trying to fix this water dispensing pump, and got stuck in between MOSFET vs transistor working principles.
For some reason the MOSFET stopped working and the pump as well.
Now I am trying to ...
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My Tesla coil is not working
I made a Tesla coil, but it doesn't not work. I used this circuit:
I used 200 turns for the primary coil with 0.5 mm wire and 5 turns for the secondary coil with 1 mm wire on a wooden rod.
Back to ...
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