Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [saturation]

Saturation applies to two things in electronics; core saturation in a transformer or inductor, AND transistor saturation in a BJT or a MOSFET.

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How do I saturate an NPN transistor?

I understand that in "saturation mode", a BJT functions as a simple switch. I've used this before driving LEDs, but I'm not sure I understand clearly how I got the transistor into that state. Does a BJT become saturated by raising Vbe above a…
Mark
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What is saturation in an inductor

I have heard a lot of the time that "the core is not large enough to handle the current, and will reach saturation". What is saturation and why is it a bad thing to reach saturation?
skyler
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How do BJT transistors work in a saturated state?

This is what I know about NPN BJTs (Bipolar Junction Transistors): The Base-Emitter current is amplified HFE times at Collector-Emitter, so that Ice = Ibe * HFE Vbe is the voltage between Base-Emitter, and, like any diode, is usually around 0,65V.…
Denilson Sá Maia
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Calculating the saturation current of an inductor?

How can I calculate saturation current of a Toroid inductor, with a core? What effect does the current have on the inductivity after crossing the saturation current?
Sherby
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Why is there a large "well-shaped" distortion when the input voltage exceeds the power rails of an op-amp?

The specific model in question is the LM258 op-amp. After looking at its datasheet I understand why the output swing at both the positive and negative voltages, however I don't understand the physical scientific reason as to why the waveform…
Sajidur
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Why do we want gap in the core material while designing inductor?

In some cases it is necessary that core of inductor should have a gap, unlike with transformer core. I understand the reason with the voltage transformer core; there is nothing to worry about core saturation and we want to keep the winding…
hkBattousai
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Prevent high-side BJT saturation

I am building high-speed (10-20ns on BC847-class transistors) digital "buffer"/"inverter" out of BJTs. Scheme is attached. While I can prevent saturation of low-side BJT by adding Schottky diode, it's not going to work for high-side. Any hints…
BarsMonster
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Simulating Chua's circuit in LTspice with a saturating transformer-based nonlinear resistor

Chua's circuit is one of the simplest circuits known to exhibit chaotic behavior. It consists of resistors, capacitors, an inductor, and an active nonlinear resistor. One implementation of this nonlinear resistor is given in the figure below of…
Vivek Subramanian
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I designed and built an op-amp using 4 NPN and 2 PNP BJTs. What are the pros and cons, and how can it be improved?

There have been some questions asked recently about op-amps, and I was curious to see how to make one with just NPN and PNP transistors. I did a simulation in LTspice and it seems to work pretty well, and I think it would be useful to illustrate the…
PStechPaul
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A question about Vce of an NPN BJT in saturation region

Below is an NPN transistor symbol and the voltages at its terminals are Vb, Vc and Ve with respect to the ground: I read that: during the saturation the Vce = (Vc-Ve) settles to around 0.2V and the further increase in base current will not make Vce…
user16307
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Why does a C4467 transistor turn off slowly when collector-emitter current is low

I built the following circuit simulate this circuit – Schematic created using CircuitLab The clock has an amplitude of approx. 5 VDC. It's provided by a 555. I used two different values of R2 for my tests. The first test was R2 = 6 ohms. The…
Eric Urban
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How to prevent op amp from saturating?

How can an op amp be prevented from going into saturation if the feedback is intermittently disconnected? For example, in this circuit (simplified case of a real-life problem), the op amp acts as a current source to a load, but the load may be…
Alex I
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BJT - absolute maximum base current?

Let's look at the datasheet for an MMBT3904, just for example. The absolute maximum section talks mostly about maximum voltage differences, and a single current limit - the collector current. I'm used to using these, and similar BJTs as saturated…
nsayer
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Self-made Schottky transistor doesn't behave as I'd expect

For a project of mine I need to generate UART-like signals with higher voltage (up to 18V) and a baudrate of 115200 bps and later possibly 250000 bps. I tried a basic BJT level shifter which worked as shown below: (here and later: yellow in IN,…
Dmitry Grigoryev
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What is the difference between "Collector-Emitter" and "Base-Emitter" Saturation Voltage?

As you can see on the datasheet below for the 2n2222a NPN transistor, the "Collector-Emitter Saturation Voltage" and "Base-Emitter Saturation Voltage" are defined respectively as 0.3 to 1.0 and 1.2 to 2.0. I believe I understand transistor…
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