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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Interpreting the state of the transistor
In this scenario, let's say that XMM2 has a reading of 0 A and XMM3, being a voltmeter, has a reading of ten volts.
I presume that XMM2 reads the base current, so since there is no IB, there will also ...
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Transistor how to turn lamp on/off
I am trying to design a very simple schematic and trying to understand how the transistor works as switch.
Transistor: Datasheet
Description: NPN - Pre-Biased 100mA 50V 100mW USM(SC-70-3) ...
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Shorting NPN transistor base to ground
What is the normal convention(safe and reliable), should one connect NPN transistor base to ground or should a resistor be used?
My logic tells me that in common emitter mode, shorting base to ground ...
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When using an open-drain output to drive an NPN transistor, can the base resistor be replaced by a pull-up?
Assuming the value of R1 is the correct value for the base resistor for the given motor L1, is it okay to omit the additional base resistor, used in push-pull applications, for an open-collector ...
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switching shape memory valves with microcontroller using NPN transistors
I am using a standard NPN transistor-as-a-switch set-up to use a Teensy 4.0 to switch a bunch of shape memory valves (valves controlled by a wire that changes shape when heated by a current). I have ...
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How to tell if a proximity sensor is NPN or PNP?
I have a proximity sensor without nameplate. I have done some tests that made me think it is a PNP (normally open).
Is my assumption correct? Is there another method to find out?
Test setup:
Supply ...
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Load resistance of this circuit
I want to make sure I understood this correctly .
If I want to measure the load resistance of this circuit, is it between (A - G) ?
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Transistor: Getting “incorrect” graph for input voltage to output voltage
I tried drawing the graph of \$v_o\$ vs \$v_i\$ for a bipolar junction transistor. I used the below setup (common emitter:)
By design of how the base is a small part compared to others, \$I_b <<...
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Two PNP Transistors - Jumper Collectors with Emitters and Bases at Same Potential?
In the attached image, OUT1 and OUT2 are logically identical (provided for redundancy).
I'm wondering if it's valid for OUT1 and OUT2 to be tied together and brought across a single load? This is ...
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Driving lamps with the fewest number of NPN switch transistors
I'm building a small system to drive some Nixie lamps and I'm missing some of the classic ICs that could make this design significant simpler. I ended up with some discrete NPNs to select the lamp and ...
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Problem in 5v pump
I connected the pump to tip122 darlington transistor to control it via serial port.
but the pump doesn't work. instead , it makes sound.
how can i make the pump work
the circuit of the tip122 :
the ...
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Help solving thermal runaway in voltage follower circuit
I'm trying to build a circuit to drive a heating element. In testing a portion of the circuit, I've noticed what looks like some kind of thermal runaway in the Darlington transistor I'm using, but I'm ...
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LTSpice BJT Model Help
I am new to LTSpice and I was trying to make some experiments with BJTs. In particular i was trying to model a npn with VbeON = 2V. From the the ltspice site i found that the built in potential of the ...
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NPN transistors as a switch with an Arduino
I'm trying to use 2 NPN transistors as a switch as shown in image-1.
When I connect pins 4 and 5 of the Arduino to the base of each transistor it works fine, but when I try connecting pin 5 to the ...
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NPN BJT common emitter amplifier input impedance
I am trying to find the input impedance of this circuit.
In this circuit 10K resistor is load.
I looked at my book but could not find any circuit looking like this because none of them has C1 ...
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BJT Constant Current Driver
I'm currently working on this circuit and I ran into 2 questions that I'm not sure I understood them correctly ( I have U1 = 15V , URE = 2 V , β = 180 , UCE = 5V and a constant current I = 2mA )
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Transistor is OFF but the voltage at the emitter is the same as voltage at the collector
This is simple simulation below of an NPN transistor:
In the above transistor, without giving any base voltage, whatever voltage I give at the collector of the transistor, I am getting at the emitter....
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Best way to AND all connected inputs to one output
I have an CNC router with 7 x SN04-NPN sensors connected in parallel with one control board input. The problem is obvious, i got random false endstop triggers due leaking of SN04. I know i should have ...
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Transistor in cutoff mode but still allows current to flow
Hello everyone,
I am a freshman in computer science, and as we are dealing with a lot of hardware, we stumbled upon transistors. We learned that if a transistor is in cutoff mode, it basically acts as ...
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LTSpice RF transistor 2 emitter "the instance has fewer connection terminals than the definition"
I am trying to use the Infineon spice model for BFP640ESD (link for library file), but it has two emitter terminals and I'm not sure how to use it since the BJT models have only 3 terminals and I need ...
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Head to tail transistor pair, not a Darlington pair, not a Szlikai Darlington
I recently reversed engineered a discrete voltage regulator from a board that was performing quite well, and I stumbled upon a weird transistor pair circuit.
simulate this circuit – Schematic ...
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Understanding the VI output characteristic of NPN transistor in the saturation region
I have trouble in understanding the VI graph of the output current (collector current \$I_C\$) in the NPN transistor. More precisely the common base one (this is the first type of transistor I came ...
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Altering PWM on four pin fans using only transistors
I have some high RPM 4 pin Tacho PWM fans, they run at 6000RPM and 56.5 DB at 100% duty cycle the noise is enough to drive you insane - there are seven of them total running off of a SAS backplane, ...
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Constant current limiting circuit
Can someone help me understand the working of this circuit:
My questions :
Please explain me how this circuit will work in its entire operation range.
I am not able to understand the purpose of the ...
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NPN circuit (breadboard)
What does this NPN BJT circuit represent, is it a switch or just a PN diode, and what should this plot look like when we sweep the value of Vbe, and why?
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Can someone explain this part of circuit from BQ500212A?
As the title says, I am struggling to understand what this part of a circuit does. It's part of this evaluation module.
Is there any chance the BSS138 transistors will activate without the SNOOZE/...
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Calculating base current without knowing current amplification
So I'm currently doing an assignment where I'm meant to design my own common emitter. I'm supposed to choose the Q-point of my collector current and choose my own signal amplification (Av). During ...
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LED Controller Circuit Design with BJT
https://www.circuitlab.com/circuit/mthven79a2m6/led-controller/
I designed a LED controller to turn the led on/off. What do u think about my design?
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2N2222 low side relay switch not turning off
I've been pulling my hair out over this for weeks and I can not for love nor money work out why it's not working.
I have a very standard NPN low side switch setup to turn a relay on/off from a 3.3V ...
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Why does this 8 step sequencer schematic need two resistors for each output pin?
I've found a schematic online for an 8 step sequencer and built it on a breadboard. Before I start experimenting with it and adding features, I'd like to find out if both 10k resistors are needed for ...
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What can I do to get a stable bias on this current sink?
I am still working on trying to get a stable 60 Hz ramp generator with a down-slope, and I am trying to do it from first principles and as simple as possible to understand fully what I'm doing.
I got ...
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Is a resistor compulsory in a NOT gate made from an NPN transistor?
I am making a NOT gate using a BC337/BC547A transistor (tried both) and I have made this circuit (image shown below) using a simulator:
This is working properly. However when I remove the resistor R1,...
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My FM transmitter never works, Why? [duplicate]
I'm trying to build a FM transmitter, but without sucess. The current schematic I'm using is this one:
The alternating current at the (+) of the op amp is the P2 output of my phone.
V3 and V4 are 2 ...
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what kind of transistor is this?
I'm just beginning to understand a bit about transistors and wanted to build my own NOT gate with what i thought was an NPN Transistor. When it didn't work I thought maybe i had the pins mixed up and ...
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How do you get transistor voltage when you only have currents?
β=50 I need to find Vbe and Vce
So obviously it is a NPN transistor, the current is flowing in the same direction so it is in active mode.
Ie=Ic+Ib
1.2mA=1mA+Ib
Ib=0.2mA
Vbe should be around 0.7V for ...
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Can a D667A NPN transistor be replaced with a BD139 NPN transistor in this PSU?
I have a PSU that had a D667A NPN transistor that took some damage. I am not 100% sure what its goal is in the circuit, but I have the impression it is used to drive the power transistor mounted on ...
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NPN Transistor problem
I need to find Vce
Would this be correct way of solving it?
I got 7.551V for Vce
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BCW71 NPN transistor as a switch
I have a simple circuit using an NPN as a switch using the BCW71 (https://www.mouser.es/datasheet/2/308/BCW71-D-1802620.pdf), as seen in the following picture:
My issue is that when I put 3V3 at the ...
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Using a transistor as diode [closed]
What are the advantages of using a transistor as a diode after interconnecting its collector and base?
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How do I connect a NPN transistor so it operates in the saturation region?
I am learning about NPN transistors and I could not find how to connect the transistor so it operates in the saturation region.The circuit that I have made works in the Active region,because when I ...
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Understanding the 2N2222 transistor, Where is this voltage coming from
I was using Proteus to simulate NPN transistor then I saw this
Both Switches are open. Why I see 3.12 Volts
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Common emitter bandwidth and probing
I am trying to design a simple RF amplifier for a 1MHz AM signal (for low-power transmission). My modulator (JFET-based) outputs ~...
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Will my 555 timer circuit work the way I want it to?
Essentially, I am trying to implement a safety system for another project of mine. I am running a very high current through a rather large solenoid and want to ensure that a failure in its control ...
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Using P-Channel mosfet with arduino
I want to drive a 12v inductive load with arduino (a motor) . This device has 3 wires a common GND and one wire to go in one direction an another one to go on the opposite direction, as it has a ...
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Simulation shows mystery leakage
Background:
I am trying to design a battery powered gate opener, the basic concept is that if the uC switch is on the relay switches the motor on, but if the actuator gives a low feedback (gate is ...
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NPN transistor switch wireless charger module
I am using this module for wireless charging, as a receiver, and i want to switch it on and off, because firstly it consumes about 5mA when idle and secondly i want to power it off when the battery is ...
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Transistor Input ON Voltage
I have this BCR116 NPN Transistor
In the datasheet, they mention as Input ON Voltage instead of Base Emitter voltage like below :
But my doubt is, when they say Input ON Voltage is 0.5V minimum, ...
user220456
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How can I make my voltage divider work?
I'm trying to read the voltage of the battery so I can simply calculate the battery status.
I'm using a 8.4V battery (recharcable PP3) that I've meassured now to 5.57V. The circuit will die long ...
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High side switch sensitivity
I am trying to build some device that will emulate the operation of some module in my car. The input is the 12V logic signal from the trasmission control module. Basically, the device should take ...
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Current mirror collector voltage
I'm trying to get the VGS of DMHC4035PMOS. Based on the simulation, I'm supposed to get -5.53V but I'm getting -8.2V on my PCB. Is there anything wrong with the design? What is the collector voltage ...
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