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Questions tagged [bipolar]

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1
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2answers
73 views

Can I change op-amp supply voltage without affecting circuit behaviour

I am working on an audio project which is based upon various sections of several different schematics from various old musical instruments. I want to make a test board that has multiple different ...
3
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4answers
346 views

Gain in current but not in voltage -transistor “voltage follower” set up

Suppose we have the circuit set up as shown in the image. Also suppose that $$V_s=\overline{V_s}+v_S$$, where the smal v is for the variable component of the signal which varies much faster than the ...
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0answers
50 views

1.8 V to 5.0 V level shifter with low delay and low rise time

i have a problem with finding the right components and circuit for the following problem. I have a device that is producing trigger signals with a length of 100 ns at a amplitude of 1.8 V (left part ...
0
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1answer
34 views

Confusion with understanding the fixed bias circuit

Below shows a bipolar transistor in fixed current bias configuration. A text says that this topology is independent of β: What I understand is, since Vcc, Vbe and Rb is constant the base current ...
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0answers
39 views

Bipolar, tristate-able, overvoltage capable, digital output stage?

I need a digital output driver, with 5V TTL input and bipolar output voltages supplied from -10V and +10V rails. It must be able to go to tristate. It must drive about 5mA. In tristate it must survive ...
1
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1answer
180 views

High voltage linear regulator (with pre-regulator)

I need to build a linear voltage regulator like this: The problem with the usual linear regulators (LM317, LM337, ..) is the limited voltages they can withstand. I have taken inspiration from a ...
0
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0answers
53 views

Differential Amp - Bipolar transistor

I can't get the same answer as they are getting.. Here is what I'm getting: $$ Acc = \frac{V_{oc}}{v_{ic}} = \frac{-R\beta i_b}{v_{ic}} $$ $$ i_b = \frac{v_{ic}}{r_{\pi+2R_0}} $$ => $$ A_{cc} = \...
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0answers
240 views

Bipolar Stepper motor with Arduino and SN75441ONE driver isn't using 12V power supply

I'm a total newbie with stepper motors and have a problem I need to solve urgently, but fortunately it feels like an easy one for you pros :) I'm really just trying to make it run, nothing special. ...
1
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1answer
381 views

Inner structure of a bipolar stepper motor?

The classic diagram looks like this with coils just positioned sideways to the rotation I'm not sure if this is just a schematic or it indicates the actual structure. However I assume the actual ...
0
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1answer
111 views

Using an NPN tranistor as a switch for two bipolar stepper motors

this is my first electronics project which requires controlling 2 different stepper motors with two motor drivers (L293D). I have found that the number of GPIO pins on my microcontroller (ESP8266) is ...
2
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2answers
102 views

Doubts on Semiconductor Physics

I'm really confused about the working of a Bipolar Junction Transistor (N-P-N). Just consider the below figure: 1) Clearly the Base-Emitter junction is forward biased and Base-Collector junction is ...
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0answers
76 views

what is normalized transconductance uesd for?

The transconductance is defined e.g. for BJT by gm = dIc/dVBE with VCE=const (1) where Ic is the collector current and VBE is base-emitter voltage, and from (...
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2answers
179 views

Issue with bipolar to unipolar opamp circuit

i want to measure ac voltage.For that i need to shift an ac differential voltage (+1.23/-1.23 across R20) to 0v - 2.5v range for a unipolar adc.The R1,R21,R22 divides the voltage and gives +/-1.23v ...
3
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3answers
438 views

DC to bipolar DC converters? [closed]

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 ...
0
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2answers
55 views

tri-rail power supply from cheap buck converters

I'm looking to build a 3 rail regulated supply (+5v, +-12v) and I've got a bunch of cheap but functional buck converts from aliexpress. I'm wondering if I can run these off a single AC-DC converter (...
0
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1answer
91 views

biploar amplifier, voltage gain, and determining resistor values

i've been struggling with this problem. it says that i need to set the resistors of this circuit that produces the highest voltage gain as possible. i got the voltage gain equation, but don't have a ...
0
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0answers
141 views

PSpice Bipolar Junction Transistors Modeling

i want to simulate the circuit AmpopTBH2, on PSpice. On image 1hbt.png we can see that Draft4 is working fine, on image 2hbt_pardif.png is the same circuit as Draft4 but on PSpice that circuit won't ...
0
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1answer
106 views

What would happen to the DC bias voltage of the emitter if this capacitor is omitted?

I'm not quite sure what the question means. I need to explain what would happen if I removed the \$1.0 \mu F\$ blocking capacitor from this circuit. Howver, I'm not sure what the "DC bias voltage of ...
0
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2answers
300 views

Can a 4051 Multiplexer accept +/- 12v bipolar power

I'm looking to use a CD4051B multiplexer as a digitally-controlled switcher for audio signals. The audio is coming from the HP / BP output of a voltage-controlled filter in a synth. The signal ...
2
votes
1answer
399 views

Why do we still use Bipolar Transistors for Class A,B Amplifiers?

I'm working on a 4MHz HF power amplifier (Very simple) and was wondering why people still use bipolar transistors for class B amplifiers? Do they have better linear current gain etc. vs a FET? Is it ...
0
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0answers
375 views

Rin, Rout and Gain of Power Amplifier

I'm trying to find the input resistance, output resistance and gain of this circuit. simulate this circuit – Schematic created using CircuitLab My textbook only has the simpler case when \$R_1 ...
2
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4answers
441 views

DC Output Voltage of BJT Differential Amplifier with Active Load

I want to compute the value of VO. simulate this circuit – Schematic created using CircuitLab I would have guessed that VO = VCC - VEB. Asuming VCC = 5V and VEB = 0.6 V, that would render VO = ...
2
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1answer
870 views

Bipolar constant current source circuit

I want to make a constant current source for a few dozen (say 30~60) 2-lead bipolar LEDs by combining a constant-current (CC) source circuit with an H-bridge circuit: simulate this circuit – ...
1
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3answers
2k views

How does the current travel in Bipolar Junction Transistor (BJT)?

I am completely unable to understand the current direction in npn transistor. in figure 1, the red arrow indicates the electron flow(which is from emitter terminal to collector terminal). thus ...
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0answers
58 views

Bipolar transistor problem

Could anyone help me with this problem? I have tried approaching to determine transistor state, so capacitor would mean open circuit, but I get that base currents of both transistors are zero. What ...
0
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3answers
145 views

Bipolar audio amplifier questions

Background: I designed a bipolar audio amplifier to drive a small 0.5W 8 ohm speaker. I am going to use it to listen to other circuits I make. First time doing this since college. Here's the ...
3
votes
3answers
287 views

Purpose of series resistors in this bipolar rectifier circuit?

The following circuit uses two series resistors, one for each polarity of the supply. I understand function of smoothing caps and overvoltage zener diodes, but the resistors I do not. I would like to ...
0
votes
2answers
201 views

Convert and shift voltage from DAC using opamp

I have a signal coming out of a basic DAC (resistor and capacitor) as follows: 1.4V min 4.8V max ~2.8V pp I have a bipolar supply that is -12V - 0 - +12V What is the best way to shift this signal ...
4
votes
1answer
335 views

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 ...
4
votes
4answers
1k views

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, ...
3
votes
3answers
141 views

Bipolar signal amplifying to high voltage

I have a bipolar (+-15V) square wave with a frequency of approx. 600 kHz. I want to amplify it to +-500V (not precisely), 50W. The load is around 1kOhm. Can anyone give me an advice on how to do it?
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2answers
2k views

low power alternatives to LM741? [closed]

I am trying to build a triangle wave generator and the op-amp that kept getting recommended was the LM741. However, according to the datasheet I found, I need to have at least a 10V source to power ...
1
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2answers
244 views

Modelling transistor V_be and bulk resistance

I'd like to calculate algebraically the DC behaviour of various bipolar transistor circuits that used matched pairs or quads (exponential converters, current mirrors etc.), taking into account the ...
1
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1answer
172 views

Is it feasible to chain high voltage dc boost converters together to get bipolar (dual) output rails?

I have two Recom R24-150B dc-dc converters (24V in, adjustable up to 220V out) and I want to have +/-220V output rails. The converters need a resistor between the - (COM) output and their adjust port ...
0
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1answer
69 views

Which are main purposes of bipolar transistors? [closed]

In school, we learned a lot about transistors but I still don't get its point. I understand gain and amplification of voltage or current or both, but I don't get it how can it be used for example as a ...
1
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2answers
150 views

Amplifying and Measuring Bipolar Signal

I have a continuous bipolar signal that can vary between ±1 mV and I would like to figure out the best way to measure it with high resolution without introducing a lot of noise. My first ...
0
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1answer
253 views

Bipolar Li-ion battery charger

I'm currently designing a small application with a bipolar power supply. As the circuit needs to be portable, I've included two Li-ion batteries in series with the midpoint grounded to generate the ...
0
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0answers
334 views

Bipolar Transistor H Bridge - low side NPN transistors slow to turn off

I've been trying to build an H-Bridge from bipolar transistors. Here are my parts for the schematic below Q1, Q2 - A1694 Q3, Q4 - C4467 Q5, Q6, Q7, Q8 - 2N5551 R2, R3 - 100 ohm R5, R6 - 50 ohm R9, ...
6
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7answers
5k views

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-...