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Questions tagged [pnp]

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A type of bipolar transistor comprised of p-type semiconductor in contact with n-type semiconductor which in turn is in contact with a p-type semiconductor -> thus PNP. 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 confusing about voltage drop between emitter and collector of the transistor. Assuming the forward voltage drop is 0.7 V, why is voltage at the base 13.8 instead of 14.3 V?
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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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Why shouldn't the resistance of R3 be less than 100 ohms? (See note 12 mentioned at the bottom of the image.)
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I am trying to understand this circuit, specifically the PNP transistor pair Q8 and Q6 on the right side. The full circuit is supposed to demodulate a 40V signal that sends a few impulses around 29V. ...
fourreux'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 ...
BitLauncher's user avatar
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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 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 ...
Alejandro Fernández'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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A few months back I asked a question about how to implement a voltage regulator to reduce the given rectified 33V supply voltage to about 24V. I decided to use the LM78S24 paired with a BD536 (both ...
M M.'s user avatar
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I’m investigating some intermittent failure on a key fob. On the circuit, I found a 3-pin SMD component that I haven’t been able to identify. As far as I can tell, the package looks like SOT-23. I can ...
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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 try to decrease the voltage on the base using the R1 for turning on the PNP transistor in forward bias mode (while V(Emitter) > V(Base) > V(Collector)). But adding of the R1 hasn't any effect....
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I was referring to this datasheet of SS8550 PNP transistor. In page 3, under "TYPICAL PERFORMANCE CHARACTERISTICS" section, there is a graph of Base−Emitter Saturation Voltage and Collector−...
Kailash Kumaravel's user avatar
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Attached is the circuit I have as well as the datasheet for the BJT. The premise of the circuit is to have the PNP act as a switch for a light with a 1A max current. Typically, using no more than ...
MTham's user avatar
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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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I bought a 30A relay module for one of my projects. The image of the module is given below. https://robocraze.com/products/single-channel-12v-relay-module-30amp The schematic diagram of the module is ...
Kailash Kumaravel's user avatar
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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 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 ...
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I have this circuit here: The signals PWR and BTN_RST are used to turn on Q3, which, at the same time, turns on Q1 and ideally we'd see VBUS (3.7V), or a bit less due to the voltage drop in Q1, at ...
latiaesa's user avatar
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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. ...
Brisco's user avatar
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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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Im new to Sziklai pairs and could not find any information on how to do calculations for this case. Im trying to do DC calculations and the info i have : +IN and -IN are for AC source, the +VE and -VE ...
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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 ...
vladigg's user avatar
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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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I am trying to understand how the circuit in the image works. I have managed to understand how the 40mA constant current source works, but I cannot understand how it performs the switching between ...
Tornillo'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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Why can't I use a pnp transistor as a switch to send voltage to a battery to start charging it (the details of the charging circuit is limting current, so no damage to transistor. I Just need the ...
EETechs's user avatar
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I am continuing work on my water management system including the tank level meter discussed here Water level meter with electrodes: earthing and galvanic corrosion and my solution with the PNP ...
Gunther Schadow's user avatar
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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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How can I calculate the base voltage and base current of this transistor for any value of R1 and R2?
Serkan Kaya's user avatar
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Circuit: Tinkercad link I have been trying to learn about transistors. I understood how to work with NPN and NMOSFET transistors and on the right-hand-side of my project you can see the NMOS demo ...
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I’m currently working on an embedded solution to replicate the functionality of an I/O module, similar to the B&R X20 series. Specifically, I want to configure the outputs so that I can switch ...
Backed4360's user avatar
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I need to wire a precision switch with the following diagram. There is an LED in the switch. Ça I just wire the black wire to ground it I don't need the signal and just want the led working when the ...
vib's user avatar
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5 answers
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here is the attached image showing 2 different configurations of npn BC547 transistor. In the first diagram, the relay is ACTIVATED by supplying 12V at the base of the transistor. Now, using similar ...
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Basically the title, I want the output to be a positive voltage when the control voltage is negative and the output should either be ground or open when there is no control signal (it is left floating)...
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First of all, I should mention electronics is not my field so my problem might be trivial for you. I'm currently working on my thesis and I need to model two BJT transistors: NPN MPSA18 and PNP AC128. ...
Sebastian's user avatar
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I am working with a circuit that grounds when a LED is to turn on. I have an 8V supply voltage for the LED, which cannot exceed 10mA. The signal to turn on the light is a very weak 6.5V, so Vbe is ...
KJ7LNW's user avatar
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Looking at the circuit below: How do I analyze it? Specifically, why is the output able to go nearly all the way to +12 V but not beneath 0 V? I'd expect that when V(sig) < 0, since current flows ...
SRobertJames's user avatar
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This problem is from Transistor circuits and applications by Cowles: Attempt at solution The circuit diagram seems incomplete to me, because they assert a +12 V potential at the emitter but the ...
Carl's user avatar
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I always see that the NPN transistor is used in handling the positive signal while PNP transistor handling the negative signal in a push pull amplifier. What is the theory behind it? Can we swap the ...
user42423's user avatar
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2 answers
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Excuse me, I'm having trouble with my Semiconductor-Experiment Exercise. The transistor code (if necessary) is A1015. Here is the question: Instead of connecting load (Resistor & LED) to ...
CÔNG NGUYỄN DUY's user avatar
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I am self-learning some electronics after seeing some "modular synthesizer" videos. I loaded LTspice (is this a good choice?) and started creatively guessing. In the diagram below ...
Tony Ennis's user avatar
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Below is a part of the circuit I created to drive the MOSFET (it includes level shift, power stage etc.). Datasheet of 2SC2411K: https://fscdn.rohm.com/en/products/databook/datasheet/discrete/...
Mhan's user avatar
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I'm making a project with an Arduino using an active buzzer 5v. I saw many forums with mixed comments about using an active buzzer straight to the I/O pins without any current limiting. Then I also ...
Kokachi's user avatar
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In the 1'st picture below I provided the amplifier circuit diagram. The 2'nd picture is showing the base signal of Q5 (green colour) and Vce signal of Q5 (blue colour). It is working as it is expected....
Mhan's user avatar
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This is from the datasheet of LM2931. What baffles me is how this actually works. The LM2931 drops the voltage to 5 V and I assume the 68ohm resistor is there to drop the voltage around 0.7 V to open ...
Joonas Joensuu's user avatar
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I sent the SPWM I produced to the transistor as seen in the diagram below. pwm frequency 10 kHz. As seen in the 2nd picture, PWM-A works fine. As seen in the 3rd picture, I shared the unzoomed version ...
Mhan's user avatar
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simulate this circuit – Schematic created using CircuitLab (circuit has been updated) I build a simple circuit like this to verify my theorethical understanding of PNP transistor work. What I ...
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