Questions tagged [saturation]

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3answers
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Determine saturation base current from NPN transistor datasheet (or what resistor do I need to ensure saturation?)

The Fairchild 2N3904 has a long data sheet so let's use that for this exercise. I'm interested in using an NPN in common emitter configuration --- it's for switching. It's my understanding that an ...
1
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2answers
1k views

Op-amp saturation problem

My design: Two cascade connected inverting amplifiers. My problem: The output of second amplifier is saturated from -0.6 to -0.7V. The supply of OPAMPs is dual (+5-5V). What is the problem? How ...
1
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2answers
407 views

Why does a Schmitt trigger work in saturation region?

Given this circuit simulate this circuit – Schematic created using CircuitLab I am trying to prove that the opamp works in saturation region as instructed in the first answer to this question :...
4
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1answer
2k views

BJT differential amplifier output saturation

I'm making a long-tailed pair amplifier using a current mirror, the circuit has the following layout: I simulated it on PSpice and it worked, you can see the bias here: I tested it in the real ...
0
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1answer
102 views

What would be the peak voltage value of two combined signals (one noise and one sinusoidal signal)?

As I learned before, the peak voltage value of two combined sinusoidal signals is the sum of the two amplitudes, for example, \$0.6\sin(ax) + 0.8 \cos(bx)\$ can be \$+1.4\$V or \$-1.4\$V. Would it be ...
1
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1answer
128 views

Why does it take several seconds of time for the photodiodes to come out of saturation?

I am currently studying about photodiodes and came across this fact that photodiodes take quite a bit of time to come out of the saturation. What really happens during this time (after it is saturated ...
1
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2answers
4k views

Common emitter characteristics in the saturation region

I'm trying hard to understand the different modes and regions of operation of BJTs. The behavior of transistor in saturation region is so confusing. I've searched in forums but couldn't get a ...
3
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3answers
77k views

What is reverse saturation current?

The official page of Wikipedia mentions that reverse saturation current is a part of minority current caused by the drift of charges. I am really confused about this. In class, we have been taught the ...
3
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1answer
214 views

DC Voltage Source - circuit problem

I'm currently trying to build a DC voltage source from an AC source to a school project. The circuit worked fine when it had no voltage regulator, as it was just a transformer + full-wave rectifier + ...
1
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3answers
880 views

Transistor saturates no matter the size of base resistor

Problem I have a circuit as depicted below, and after calculating the base resistor, I wanted to see when the base current would be too little to saturate the transistor. I kept increasing the ...
0
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1answer
1k views

Current transformer saturation

I have a current transformer from this page. I tried to measure the secondary voltage Vs when I apply Vp=230 V and I change the Ip, like this: But at some point the voltage Vs is not changing anymore ...
0
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3answers
230 views

Trouble driving NPN into saturation [duplicate]

I can't saturate my NPN transistor! Here is my circuit: simulate this circuit – Schematic created using CircuitLab The Vce is around 1.7 V, which is way above the saturation Vce of 0.3, ...
2
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1answer
1k views

What does limit transferable power through a transformer?

Assume that there is a transformer as in the image above. The applied primary side voltage \$E_1\$ is always AC. We design the transformer so that the magnetizing flux \$\Phi_m\$ does not saturate the ...
2
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1answer
282 views

coupled inductor in series

I'm planning on using a dual inductor in series mode to increase the inductance. I realize that the total inductance will be L1+L2+2M where M is the mutual inductance (when the polarity is connected ...
1
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0answers
422 views

Op-amp: Floating input (Multisim)

I found this circuit from Encyclopedia of Electronic Circuits Volumes 1 by RUDOLF F. GRAF I used Multisim to simulate. When switches S1 and S2 are open (U1A@3 and U1B@6 are floating) and I measured ...
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1answer
646 views

got a too low VCE on a Infrared Phototransistor

I used an Infrared Light Emitting Diode QED123(VF=1.7V) and an Infrared Phototransistor QSD123 in pair. I learnt from QSD123's datasheet that its VCE(SAT) under IC=0.5mA is 0.4V max. But the VCE I ...
2
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3answers
2k views

Bypassing Transistors with a Switch, problems?

While working on a design last night, I had a question pop up. Is there any risk in bypassing a transistor, with a jumper/switch? Or shorting the Collector and Emitter pins with a wire? Is there a ...
4
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3answers
171 views

Control System - Changing damping on-the-fly?

I'm trying to implement a PID algorithm on a microcontroller that controls an actuator with a hard physical limit. In MATLAB, there's no consequence to large overshoots/hitting saturation at high ...
1
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0answers
856 views

Unexpected saturation with the rail to rail instrumental amplifier AD623

I'm trying to use the rail-to-rail instrumental amplifier AD623. Here the datasheet. simulate this circuit – Schematic created using CircuitLab First experiment: AD623 set as a voltage ...
13
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2answers
17k views

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?
2
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2answers
5k views

Alternative to emitter-follower for simple BJT voltage regulator

I want to make a voltage regulator from one or two BJTs and a zener diode. However, I would like to be able to make full use of supply voltages when they are lower than the voltage that the regulator ...
31
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2answers
21k views

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?
1
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1answer
262 views

Amplifier circuit - NMOS mode of operation? Gain?

Ok I have the following circuit, with values of variables: \$\displaystyle R_{1} = 1 M\Omega, R_{2}=10k\Omega,~~ k_{n}C_{ox}\frac{W}{L}=1mA/V^2\$ , and \$V_{T}=1V\$. 1) When \$v_{IN}=0\$, calculate ...
1
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1answer
127 views

Saturating a BJT with an open load

Is there some drawback in having a BJT transistor saturating without a load? The scenario is this: BJT is driving a relay, but there is a switch to have the relay always on or off leaving the BJT ...
1
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2answers
806 views

Voltage Follower Saturation

I'm trying to use a 0.5V signal as a source. I've wired a TL072CN as follow: VCC+ to 11V VCC- to GND OUT2 to IN2- IN2+ to 0.5V The thing is when I measure the voltage on OUT2 I get 10V where I am ...
1
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1answer
1k views

LM3915 to drive more LEDs / basic questions about PNP transistors in saturation

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,...
6
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2answers
619 views

Transistor in saturation mode?

I was wondering why do we so often want out transistor to work in saturation mode? Ie. For a MOS Current Steering Circuit we want our transistors to operate in the saturation region....
12
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2answers
5k views

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'...
45
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9answers
89k views

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 ...
13
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4answers
54k views

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 <...