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Questions tagged [npn]

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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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I’m currently designing an electrical circuit to measure the voltage level of a PWM signal as part of my studies. I’m in my third year of a Bachelor’s degree in France, in a program called Electrical ...
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I am simulating a leak sensor I have designed using a comparator and an NPN transistor. Basically, when V- < Vref - the BJT will become saturated and conduct current - causing the LED to turn on (...
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I'm experimenting with the Valvecaster circuit, using a 12AU7 tube. Trying to add voltage control over the gain pot, I replaced VR1 with an NPN transistor. This works to some extent, but what I find ...
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I'm in the process of studying transistor bias circuits, and now want to analyze the dependence of the collector current on \$\beta\$ for this collector-base feedback NPN transistor with emitter ...
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My project requirement is that for a 10mV peak at a 30KHz signal, I need 2V peak(1% accuracy), DC offset < 20mV output with 10 ohm load. The component type we can use is limited(op07, 2SCR293P and ...
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simulate this circuit – Schematic created using CircuitLab Short version: When SW1 is closed, and SW2 is open: will the NPN bipolar transistor Q1 survive? Is there any thing I have to check in ...
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While experimenting on transistors and current flowing I came to the idea to set up this simple circuit It's weird... ...to see a positive voltage from the negative side of the battery on the right. ....
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I'm using the circuit below to turn DC power on and off. I control an NPN transistor and a P-CH FET using GPIO signals from the MCU. Problem: The above circuit fails to power down with a frequency of ...
MSH's user avatar
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Measurements with Swapped Emitter and Collector I wanted to measure 6 pieces of a BC547C (npn BJT) Q1...6 that each drives a relay (24 V, 75% on, 2.88 kOhm) powered by an old notebook SMPS of 19.5 V ...
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On a PS4 SAB-001 motherboard I'm trying to identify an SOT353 (2.16mm*1.23mm). Marking begins with "VT" then an unknown symbol. (maybe 7 ?). I have an exact same model of motherboard where ...
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I’m having trouble understanding the basics of the second transistor schematic (the PNP circuit). My professor said I need to get familiar with how to control a bipolar transistor in an ideal setup. ...
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I'm currently reading The Art of Electronics and I have some troubles for understanding the result of the Exercise 2.4: the output impedance of the emitter follower circuit is \$Z_\text{source}/(\beta ...
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I have the following circuit: Expected outcome: When the 5V 20khz sinusoidal signal is present the LED light is on. When no signal comes through the coupling capacitor the LED light is off. Actual ...
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My FET (Q63 in schematic) is frying once I apply power to my board. I understand that Q66's base resistor is incorrect (R1151), however to my surprise in post-analysis, it is healthy according to a ...
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I will try to summarize my problem the best I can. I have a circuit I use to generate a voltage pulse. This circuit consists on a voltage-controlled current source with a 54.9ohm shunt resistor, a PNP ...
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This circuit with BC-547 transistor, 3v battery, and a lamp will be always on. When base voltage of transistor is zero or near zero, will this circuit drain battery over time or how long can the ...
mete's user avatar
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I want to control two LEDs (red and green). The circuit is powered by 5V DC. The green LED is active 3.2V/20mA when the ESP32 pin is LOW (0V). When the pin is HIGH (3.3V), the green LED is inactive ...
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Problem: How can the attached circuit be optimized so that, over a temperature range of -50°C to 150°C, the short circuit detection threshold lies between 5 V and 9 V? Requirements: The circuit is ...
Panacea's user avatar
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You may have already seen this single-transistor oscillator based on an NPN transistor with an unconventional configuration—featuring a floating base and reversed placement of the collector and ...
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I have a device that produces 12VDC from a lithium battery. When battery goes low, it doesn't cut power and still produces voltages below the designated output. As a low voltage disconnect circuit on ...
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I'm trying to understand this voltage regulation circuit. I input this circuit into LTspice. When there's no load attached, the VCC output is clamped to 9.1 V by the D1 Zener diode. Once I added some ...
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When I turn on the right most switch the LED glows more brightly than it normally does (that is, both switches off.) The LED doesn't glow more brightly upon turning on the left most switch. Before ...
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I was told that this circuitry is able to provide 24V when the secondary voltage (Vsecondary) is not yet present. I understand this part, as there are two Schottky diodes, D2 and D3. What I don't ...
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this is a follow-up to my previous question, where I received helpful insights regarding signal integrity and transistor protection. I moved the led circuits from the rs232 side to the ttl side. Since ...
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I’m designing a common-emitter Darlington pair circuit as a learning project, but I’m running into discrepancies between my theoretical calculations and simulation results. For both transistors the ...
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I’m new to this topic, so I apologize if my question sounds dumb. I cannot understand how transistor T1 enters its active/saturation state in this configuration. As soon as the circuit is powered, ...
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What are the differences between these two P-N junctions that causes them to exhibit different behavior when they are reverse biased?
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At the moment, I manually plug in jumpers on an adapter board, depending on whether I have an NPN or PNP input (40 inputs). Now I would like to replace the jumper. However, I cannot provide an ...
TubaMen's user avatar
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I'm attempting to create a simple circuit for instantaneous switching between two separate 3.3V digital input signals, based off of a single digital select signal. So: two digital ...
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Consider the LM393 comparator: https://www.ti.com/product/LM393 As far as I understand the output is basically the collector of an NPN transistor, with the emitter tied to ground. Consider it with the ...
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I have not designed a class-A NPN common emitter amplifier until today, so I hope you can look at the circuit and the tracings to verify whether I've done things correctly. I drew the schematic in ...
A Bit of Help's user avatar
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I am currently working on a homebrew single-bit computer from transistors (primarily NPN, as that's whats most described online, etc, but I'm not opposed to PNP either). To start off, I am a beginner ...
ThePlaneGuy45's user avatar
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I'm attempting to build a DC inverter (NOT gate) circuit with NPN transistors that does not experience a voltage drop on its output. I have a basic understanding of electronics. In the Falstad ...
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I’m looking for this component. It is very very small. I have a rework heater. I was able to remove the bad one. It’s marking were M3EWA. It has the same markings as several other ones on this board. ...
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I'm confused as to why this circuit uses Sziklai pairs that are meant for huge current gain if most of the amplified current at output - the emitter of NPN resistor gets drained through 2.2k ohm ...
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I noticed that on the LM108 schematic shown below (also available from https://www.analog.com/media/en/technical-documentation/data-sheets/lt0108.pdf, page 8): NPN transistors are drawn in 2 ...
user487875's user avatar
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I’m analyzing BJT transistor data and trying to calculate the Early voltage \$V_A\$ using two methods: Plotting \$I_C\$ vs. \$V_{CE}\$ with \$I_B\$ held constant. Plotting \$I_C\$ vs. \$V_{CE}\$ with ...
לירן גלמידי's user avatar
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I might know how to do it, but not so sure about it, cause I forgot how I did it last time and fear that I would burn the machine's interface if I do it wrong this time, so help me to eliminate the ...
castiel's user avatar
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I'm working on designing a circuit which involves NPN transistors, and I'm running into an interesting phenomenon that I don't quite understand; I'm observing current flowing in reverse direction ...
Runsva's user avatar
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1 answer
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I have ESP32 with one pin with 3.3 V High level and 0 V low level. I want to control red and green led from this pin: I want to power leds from 12 V power source. The red led is 2 V 20 mA, green is 3 ...
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I'm simulating a BJT-based push-pull circuit used to drive a PFET as shown below in LTspice but the gain factor of PBHV8140Z (NPN) seems incorrect. I'm seeing 1.96uA into the base, while seeing 1.14mA ...
Ken's user avatar
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Can this one cell LED driver work as an astable multivibrator? if so how is it compared to the Garner's Oscillator? They look very similar, are they the same? Is the inductor coil playing a ...
Tiago Pimenta's user avatar
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I understand that in NPN transistors when the base is higher than 0.7 volts, it allows a large current to flow from the collector to the emitter. In PNP transistors, the opposite happens. When a LOW ...
frequency_abovetime's user avatar
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I have been trying and failed. Here I have placed a JFET instead of the second NPN, but it doesn't matter, I just can't fork off enough current from the output into the rectifier and smoothing ...
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This circuit is from an old Dick Smith Electronics project book. It’s an FM transmitter. I’m wondering why the antenna is connected at a tap of the coil, rather than at the collector. Is it to ...
Greg Bell's user avatar
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2 answers
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According to 2N2222 NPN datasheet, the transistor's collector-base breakdown voltage is 75V, and collector-emitter breakdown is 40V. So the transistor should work with 12V at collector, in the simple ...
g00dds's user avatar
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I am repairing an old high voltage power supply. The supply has a step-up transformer with 500V and 20V secondaries. The 500V is further increased to 1000V with the help of the diode doubler circuit,...
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I recently made this inverter circuit, I believe that there are some potential short-circuit issues in my diagram. I could be wrong tho. There are two groups of NPN transistors in my circuit, A and B. ...
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I have a water level meter which uses electrodes. simulate this circuit – Schematic created using CircuitLab The circuit detects contact of electrodes with water, at different levels, that go ...
Gunther Schadow's user avatar
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I need to design a "Soft Power" circuit to turn on a power supply when the PFW line is high (5V). I came up with the following drawing, after using the following "sources" for ...
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