Questions tagged [active-components]

Components which provide a gain in the circuit where they are applied. Typical examples are transistors and op-amps.

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One Port Microwave Active Network Electrical Model

let's consider an active one port network: My book does an analysis of it by considering the Poynting Theorem, in which we consider the contributions of active sources (electric and magnetic current ...
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Why does moving this ammeter change the polarity of the applied voltage?

Note: I'm not an electrical engineer, I'm a materials engineer. So maybe this question has an obvious answer, but I couldn't find one with a Google search. I also have no idea if I tagged this ...
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Darlington array: How to output desired voltage at uln2803a driver colectors?

Someone suggested this driver array to get the current I need: datasheet I also need a 12V signal and about a current of 100mA in order to control a relay coil. My 12V signal would come from a logic ...
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160 views

Why isn't this active rectifier circuit working?

I built the following active rectifier schematic on a breadboard, and inputted a 15 KHz 1V peak to peak sine wave from my signal generator. The output looked like a sine wave and I have no idea why. ...
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584 views

Is MOSFET active device?

The V-I characteristics of MOSFET lies in the first and third quadrant. Therefore it should be passive device acc to me. But I have read that it is an active device. Can somebody tell what is wrong ...
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Simplest latching circuit with press-ON hold-OFF button that can cut power when Raspberry Pi halts

So I'm making a battery-powered Raspberry Pi project, and it would be ideal if it could cut off power to the Raspberry Pi after the Raspberry Pi shuts down. It would also be ideal if the power for ...
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4answers
233 views

Why are active loads used for transistor amplifiers?

I get it that voltage drop across active loads are less compared to passive loads and at the same time they offer high small signal impedance thereby increasing gain. I cannot understand why DC ...
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101 views

Is there a standard component that can “save” a certain current or voltage and what is it's name?

What I am thinking about is something like this analog equivalent of a flipflop: ...
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4answers
165 views

How does an active device work as an oscillator when its output is fed back to the input?

In the book The Art of Electronics by Paul Horowitz and Winfield Hill, it is mentioned that "Device with power gain are distinguishable by their ability to make oscillators, by feeding some output ...
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349 views

How can a USB cable extender boost the signal without an external power source?

I've been searching online for a USB Cable extender for a rather long distance (let's say 10 meters). I'm familiar with the notion that the longer the cable, the weaker the signal might get, more ...
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57 views

Z-parameters measurement in active circuits

What difficulty faced in measuring Z parameters in active circuits, how is it taken care of?,what is limitation at high frequency? I heard that we use inductor instead of open ckt and capacitor ...
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1k views

Detecting Specific PWM Signal Without Programming (Only Electronics Components)

I want to detect a specific PWM signal by electronic circuit components i.e. transistors, opamps, capacitors. update: I want to build simple ID system. I want to detect specific PWM signal for example ...
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Why can't passive components transform energy from one form to another [closed]

In parts of electrical components active components can control the flow of current in a circuit but passive components cannot. What is the factor that gives active components the ability to control ...
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Other active component principles of operation

Besides valves and transistors... On another question, someone talked about magnetic amplifiers, but they are slow. Are there any other kind of "would-be" transistors out there ? A transistor that ...
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Advantages of depletion mode FET devices over enhancement MOSFETs

I've grown the impression that JFETs and depletion mode MOSFETs are not used very much nowadays, especially in new designs. I know that they need different bias networks, especially as discrete ...
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1answer
240 views

OP AMP as active negative resistors

Was reading about OP AMP and saw a article on "Active Negative Resistor" on wikipedia @ http://en.wikipedia.org/wiki/Negative_resistance. Question to the gurus: How practical is this? Can I build a ...
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What to expect when i place a diode in magnetic field

I am designing a PCB that senses basic NTC values and converts it into digital format. The problem is the entire PCB is above a magnet(about 70mT at the board) that is moving. Hence i want to know ...
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How can I tell if a given MOSFET can be fully driven by 5V TTL high signal? (what should I look for on the datasheet?)

How can I tell (by reading the datasheet) if a specific MOSFET can be turned fully on (with the minimum drop) with simply 5V on the gate? (assuming 5V or 12V potential between the drain and source). ...
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349 views

Can electronic components work without power?

Can electronic components work without power,with the help of temperature? according to my knowledge,I don't think so,until heat will generate some energy and that will drive component. I have to make ...
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2k views

Which is actually an active component? [duplicate]

"An active device or component is something which can provide an infinite energy or non-zero power for an infinite interval" I learned this definition for an active device in a book, which is valid ...
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What is the transfer function for a first order active high-pass filter

What is the transfer function for the below circuit? simulate this circuit – Schematic created using CircuitLab Since the op-amp has unity gain, the transfer function should be the same as a ...
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1answer
516 views

Differential amplifier with active load Sedra Smith

I'm studing differential amplifiers on Sedra Smith book, and I have come across the following circuit. My question is: how can NMOS transistor \$Q_2\$ have a current \$g_{m2}\cdot v_{id}/2\$ if the ...
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1answer
3k views

Power switch between two sources using mosfets

A new problem I have is to create an automatic switch between two sources, only one of the sources should be active at a time. There is a "backup" source (5V battery), as well as another source. Once ...
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Why is Vbe a constant 0.7 for a transistor in the active region?

I'm going to take an example of a simple common emitter amplifier. Forget about biasing and things for now, but focus on the crux of this circuit. As how I understand it, a voltage between the base ...
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179k views

Differentiation between passive and active components

While I (most of the time) know from experience what components are generally considered active or passive, I have yet to come across a satisfying definition. Why do we divide electrical components ...