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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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The devices below are both n polarity devices, the BJT is a NPN and the MOSFET is a NMOS. For the BJT in cut-off, why do we have to assume \$V_{ce}>0\$? For the MOSFET in cut-off, why do we have to ...
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The Circuit Below is a "Short Circuit Protection", and Circuit Detail is : Voltage Regulator: LM2576 Maxixmum Load Current (i): 3A Output Voltage: 5,12 and 15 Volts The Original Circuit is Low Current ...
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I have a 3.3v line, which I will need to pull low intermittently with a microcontroller to send data. I have tried using a BC547B NPN transistor (also tried BC337, BC517 and BD139) with the Collector ...
Matt's user avatar
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I want to install an led board with a switch in my car. The switch would be pressed down by the lid of the arm rest when closed. I only have N.O. tact switches to use for this, since I need momentary ...
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I want to replace an ON Semicondutor BC557 PNP transistor with a Multicomp BC557 PNP transistor. It is just for general switching of LEDs. But the specs look different although they are same mode. ...
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Is there a simple method to do a sanity check on a bipolar junction transistor whether it is still functional or defective? simulate this circuit – Schematic created using CircuitLab Say for ...
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Following circuit is used as a switch in one my circuits. The collector is connected to the Vcc and emitter is supplying current. Theoretically it is wrong, right? The supply should be connected in ...
Basheer's user avatar
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My book (teach yourself electricity and electronics) talks about the static forward current transfer ratio ... ratio of collector current v.s. emitter current when we place the base at electrical ...
Jimbo's user avatar
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I have been reading that NPN transistors are sinking and PNP are sourcing devices. I do not really understand this concept. It says current source device connects load to Vcc and current sinking ...
Abhishek's user avatar
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Is the following circuit electrically sound? My recollection is that the right way to do it is to use a PNP transistor on the high side and an NPN transistor on the low side. Will it work if they are ...
vicatcu's user avatar
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Need to repair a legacy system that has been discontinued and am considering replacing the PNP based circuit with the diode based circuit. The input signal (max. freq = 20Khz) is applied at IN and is ...
sekharan's user avatar
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I'm using the LTC5598 IC for modulation. I am confused as to how to properly feed my BaseBand analog signal into the chip. According to its datasheet: The circuit is optimized for a common mode ...
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This is a simple Class A amplifier using an NPN transistor: Is there a way this can use a PNP transistor, instead (with only 0V and +Vcc, not 0V and -Vcc)? Why or why not?
Ehryk's user avatar
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I'm looking to simply read the generic sound level from an Electret Microphone. I've seen a number of schematics with NPN transistors, that will provide an inverted output (~5V when quiet, ~0V when ...
Ehryk's user avatar
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3 votes
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I am working on a project that includes a scanning switch matrix. It also includes a joystick with an integrated push button. I am out of IO pins on the micro, but there are gaps in my switch matrix, ...
ben's user avatar
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R1 became RS R2 bacame R 1)Is this a correct shortcircuit protection? 2)What is the max current that can flow before the transistor enters in saturation?
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This is a rather elementary question but I think my fundamentals are not clear on this. What is the voltage at the common node? Firstly, I thought voltage was taken across something i.e it's taken ...
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Why not to use a P-Channel MOSFET in this circuit? It makes more sense, to me since the MOSFET act as a resistor when turned on which is better then the constant volage drop of a PNP.
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I am using the configuration in picture and the MMBT5087 PNP transistor. I am not using the top base resistor, just the lower one, so there will be 5V on the base. My question is: Using a 1K resistor ...
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I am working with a dual power circuit for using USB and a LDO at the same time with a PIC18F2550. The circuit is the same as the one in the PIC's datasheet. My question is: How do I calculate the ...
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As a follow-up of my previous too generic question I have a signal generator (shaft encoder) that has 2 NPN outputs. I have a high speed counter that needs PNP signals. How can I convert the encoder ...
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I have a circuit which requires a PNP transistor. I only have an NPN transistor. Is there a way to convert one to the other given that they have the same characteristics (apart from the npn/pnp part?...
Toad's user avatar
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I am preparing for exam and one of the questions is this: "Which part of a pnp-transistor is the Buried Layer normally connected to?" According to the lecture notes handed out, the correct answer is:...
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Usually I use NPN to drive LEDs but in my project I have to use PNP because the cathode of the LED is tied to GND. Then I have a question, is it possible to have a command of 3.3V and the PNP tied to ...
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I'm running through some old exam papers at the moment and one of the questions are: The parameter \$h_{oe}\$ is needed to calculate the output impedance of an amplifier. Explain in detail how to ...
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As a few others here, I'm trying to drive a few (10) LEDs from each output of a LM3915 vu-meter chip. I've read different posts, and it seems the universal recommendation is this great answer. I have,...
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I have an old RC car but without the transmitter so I built my own Rx/Tx using MCU and 2.4Ghz transceiver, however, I want to use the car's original H-Bridge but not sure if I understood how that ...
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I'm building a boost converter and want to implement a shutdown feature. The particular chip I'm using, LM3478, has a shutdown feature which is activated by a high level on the frequency adjust pin. ...
Emil Sahlén's user avatar
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3 answers
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I have a 5v microprocessor that needs a PNP transistor between it and the common anode of an LED display, as it can't source enough current to drive all of the LED's without burning up. I understand ...
Chris's user avatar
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Updated based on feedback with better screenshots (I hope) - I am also working on getting the files onto a file sharing site so they can be accessed at full resolution I am really confused about the ...
Mike Snyder's user avatar
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I'm not a guy from electrical engineering and I'm having a little trouble with a small garage project that I'm working on. I want to use a photoelectric sensor to measure distances. I'll probably ...
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I read somewhere that PNP transistors have lower noise than NPN transistors. The majority carriers in NPN are electrons where as in PNP they are holes, so I thought the noise would be much be less in ...
Umer Farooq's user avatar
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I am trying to interface a 3.3volt TTY bluetooth dongle to my arduino. The dongle requires 3.3volt but the arduino's Tx and Rx signals are 5 volt. Apperently the 3.3volt is enough for the arduino Rx,...
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This question is somewhat modified from the original which was asked by someone else. Note that there is more to this than meets the eye. The OP07 or OP070xxx is a 30+ year old op amp, the transistor ...
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Of the two circuits, would you prefer one over the other?
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This is not a duplicate of this question. I would like to know what the differences in their characteristics are. I'm thinking for example about their majority carriers (electrons for NPN, holes ...
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I'm attempting to use a transistor to switch on and off an SSR, which in turns switches on and off a solenoid. I originally used an NPN transistor (2N222), but this caused problems when the MCU ...
Mark's user avatar
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Suppose that I know how an NPN transistor works. How different is a PNP transistor? What are the operational differences between a PNP and a NPN?
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With the LPC1343 microcontroller (Cortex M3), there is a USB_CONNECT line which goes low when the micro is ready to connect to the computer via USB. This "soft connect" feature is implemented on the ...
cksa361's user avatar
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I can not wrap my head around the fact how I can drive a relay (24V, 160ohm) with an tip32a PNP transistor which has TTL inputs from a controller. I can easily calculate my resistors when I use the ...
Erik's user avatar
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