Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [bipolar]

86 questions
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Is there any reason to use junction or Darlington transistors for power applications?

In quite a few Arduino examples, you see people using junction transistors to power a motor. In this case, for example, he's using a Darlington transistor: http://www.instructables.com/id/Use-Arduino-with-TIP120-transistor-to-control-moto/ Is there…
Dov
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Basic electronics: Transistor switch

I am new to electronics. I am reading this book called Practical Electronics for Inventors. This is a portion about bipolar transistors from the book: There are two things I don't get from this: When the switch is thrown to the "on" position, I…
Dat
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Identification of bipolar transistors on die (pnp or npn?)

is it possible to tell from this photograph whether the transistors are npn or pnp? And if so, what is the line of reasoning? How to sort that out? This photo I took is from a Sharp GP1FAV51RK0F Toslink reveiver and shows two bipolar transistors (at…
DrSvanHay
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Orientation of "bipolar" capacitors on PCB

I've come across a video on a popular and well-respected electronics channel on Youtube where they say that even bipolar capacitors have a preferred orientation in a circuit that minimizes hum and interference etc. They describe an oscilloscope…
bs448c
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Active load role on this circuit and possible uses

simulate this circuit – Schematic created using CircuitLab I came with this circuit to know how an active load can improve it, I still can't finish to understand the role of active loads. The far I know is that below, Q5-Q6-R2 form a current source…
tac
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What does the cross point of V-I curves mean?

Here you see a V-I graph including many curves achieved under different junction temperatures of an IGBT. As it can be seen there is a cross point where all curves intersect each other. Does it make sense? If yes, what does the cross point mean and…
Albert
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Pulse oximeter design: How to drive a bi-polar LED having two different forward voltages?

My lab partner and I are building a pulse oximeter for our capstone project and could use some help. I have an ELM-4002 which is a bipolar LED with the following specifications. The two LEDs are labeled RD for 660nm and IR for 940nm. The two forward…
Riley Hagerstrom
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Proving that this JFET + Bipolar source follower give back a linear output

I was reading about this source follower and wondered how the bipolar transistor makes Vgs somewhat stable. I believe that what happens here is that when Vin is high more current flows through the base of the bipolar and then more voltage drops…
The pro coder not really xd
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Generate +/- voltage outputs using two boost converters?

I am working on a project to power some audio equipment that requires +/- 15V DC. Output current load is about 250mA, maximum. I am wondering if there’s any reason I couldn’t create this using two switching boost converters and a DC wall wart, as…
seagull48
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Why are bipolar transistors used for switching applications?

I noticed that many sites targeted at hobbyists recommend bipolar transistors (mostly NPN) to switch things on and off. Bipolar transistors definitely have their purposes especially in analog circuits, but if you want to switch a relay for example,…
Karsten
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DC to bipolar DC converters?

First of all, is there a name for thse kind of converters for easy searching? There are some voltage adjustable DC to +-5-24V DC converters on eBay but they can't handle more than few hundred milliAmps. I need a +12V 1A output and -12V 0.5A output…
Mark Legault
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How did bipolar IC density compare to MOS ICs?

Historically, how did the density of bipolar (e.g. TTL) chips compare with MOS? How complex could bipolar ICs get before they hit limits? Does anyone have a Moore's law-style graph for bipolar technology? Edit: A specific number I'd like to know is…
Ken Shirriff
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Making voltmeter accepting bipolar input voltage, using a microcontroller

I want to build a very simple voltmeter using ATMEGA328 ADC. I can successfully measure up to 20v (using a voltage divider), but the problem is, I don't understand how to measure the voltage properly, if negative and positive terminals are switched.…
0x29a
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Is this behavior realistic for bipolar loads on optocoupler outputs?

Background: When using LTspice to simulate such a circuit (the opto-model is called PC357NT and is part of some exhaustive lib called "ZZZ" which I downloaded a long time ago. The PC357NT seems to be a pretty standard opto with ~100% nominal…
tobalt
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Active load and current source purpose on NE5532

I'm trying to do some reverse engineering on the NE5532 schematic, but I can't understand how is designed the current source for the first stage. What I want to analyze now is in yellow on the picture. As I understand, the first differential…
tac
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