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Analyzing a circuit with 2 voltage sources

I don't know if this helps, or if it would be an acceptable solution to your professor, but I notice that the circuit is completely symmetrical either side of R3. That means you could split the ...
Simon Fitch's user avatar
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1 vote

Do you know this circuit?

The 2 PNPs form a simple comparator; comparing the emitter voltages. When the 3V3 level is higher than ext_3V3, the right-hand PNP will have a higher VBE than the left-hand one (since the bases are ...
jp314's user avatar
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0 votes

RC Integrator Simulation

Simply put, when you use a VCCS model, you are assuming a transconductance amplifier (like a 5T-OTA) which inherently has a large (ideally infinity) output resistance. Under such conditions, the ...
a360pilot's user avatar
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2 votes

Why does a MOSFET fail on fast signals, even if they're much longer than the turn on + turn off times?

While you may not have drawn a resistor in series with V2, the mosfet model most certainly contains one. See LTSPICE wiki: https://ltwiki.org/LTspiceHelp/LTspiceHelp/M_MOSFET.htm which in the table ...
rohmeooo's user avatar
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0 votes

How do I analyze an emitter follower with a capacitive load?

how can I predict the emitter voltage or current? Generally, you'd do it by solving the differential equation system that models the circuit. SPICE does it numerically. You may be able to come up ...
Kuba hasn't forgotten Monica's user avatar
4 votes
Accepted

How do I analyze an emitter follower with a capacitive load?

Since the transistor is only able to source current from the positive supply, implying current flowing downwards through the capacitor, and since you've provided no way for current to flow upwards ...
Simon Fitch's user avatar
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2 votes

Why is a push-pull transistor configuration asymmetric?

Each transistor is responsible for passing current in two different parts of the input/output waveform, between which current in the load changes direction. The upper transistor is allowing current to ...
Simon Fitch's user avatar
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6 votes

Why is a push-pull transistor configuration asymmetric?

Everyone has already pointed out that one of your transistors is arranged incorrectly. So I won't belabor it here. Sufficient that you know it won't work. The phrase ...
periblepsis's user avatar
-1 votes

Why is a push-pull transistor configuration asymmetric?

Your circuit is invalid. Try something like this. It can operate from a single-ended power supply. Reference the amp to 6-volts. Circuit reference https://circuitdigest.com/electronic-circuits/push-...
Dereck's user avatar
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8 votes

Why is a push-pull transistor configuration asymmetric?

But that's not a valid push-pull circuit to begin with. You have the PNP transistor upside down. Even if it were correct, for negative output you would need a negative supply and you don't have one. ...
Justme's user avatar
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2 votes

How do I analyze an emitter follower with a capacitive load?

The problem is that you're trying to linearize about a DC bias where the transistor is deep into cutoff, because there's no way for C2 to discharge. The emitter voltage is pinned to Vcc, and you're ...
Hearth's user avatar
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0 votes

How do I generate a trigger signal from a periodic analog signal having varying amplitude

I would use the following: Since you want a threshold relative to the signal's amplitude, first decide if this is RMS, average, or peak amplitude, and use the corresponding detector on the signal to ...
bobflux's user avatar
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How do I generate a trigger signal from a periodic analog signal having varying amplitude

Of course, it's impossible to have the circuit trigger as some point on the rising edge of its own cycle, since you can't know what the peak amplitude is until you reach it. You could sample the ...
vir's user avatar
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0 votes

How do I generate a trigger signal from a periodic analog signal having varying amplitude

With edge triggering, you generally have two main levels: the arming level and the firing level. When your signal passes the arming level (e.g., a 0V DC offset sinusoid rises above 0V), your system ...
Kiwi's user avatar
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0 votes

Load cycler circuit analysis

You might more simply connect the battery to either load or charger as shown here. simulate this circuit – Schematic created using CircuitLab
jonathanjo's user avatar
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1 vote

Frequency compensation circuit

Your circuit is a high pass filter. The time constant of the circuit can be found by looking at the circuit from the capacitor’s point of view. The capacitor sees R an Rc in parallel. The time ...
user69795's user avatar
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2 votes
Accepted

Where am I wrong in my derivation of RC charging circuit equation?

KVL states that sum of all voltages in series is zero. There is a constraint: The voltages of each element must be measured with the same orientation. The diagram aligns the voltages with the ...
RussellH's user avatar
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1 vote

What is the purpose of the BJT in this circuit?

There are many good answers already, but I think one key point is missing: an external BJT is used because it has better heat dissipation and power handling. The purpose of the Zener voltage reference ...
DavidG25's user avatar
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3 votes

Where am I wrong in my derivation of RC charging circuit equation?

The main thing is you lost track of the polarity of your voltages. A diagram can be very helpful in keeping track of this. From your first point about KVL — \$V_B + V_R + V_C = 0\$ — you have: ...
Dave Tweed's user avatar
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0 votes

Where am I wrong in my derivation of RC charging circuit equation?

The error is introduced in the integration, because the resulting equation has voltage unit on left side and no unit on right side.
Stefan Wyss's user avatar
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2 votes
Accepted

Why do some JFETs oscillate and others don't?

models and datasheets The MMBF4416A datasheet you provided is terrible. There are no charts given. Nothing to examine. However, my eye is drawn to this: If you now set this up in LTspice where \$V_{_\...
periblepsis's user avatar
1 vote

Relation between crossover frequency of loop gain and closed loop's corner frequency when feedback is not unity

I think your confusion comes from the definition of the closed-loop bandwidth. The closed-loop bandwidth is defined as the frequency where the magnitude of the closed loop gain is -3 db down from the ...
Simon's user avatar
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3 votes

Why do some JFETs oscillate and others don't?

Made with microcap v12, interactive mode "Stability" analysis. Just change your C1. It will start to oscillate within 250 us ... Tried until 420 MHz.
Antonio51's user avatar
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0 votes

Why do some JFETs oscillate and others don't?

JFETs have very spready DC characteristics .I have not used them in any high volume products due to fear of a production disaster. Sure people do and seem to get away with it .Try reducing R1 to get ...
Autistic's user avatar
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10 votes

What is the purpose of the BJT in this circuit?

The external transistor boosts the output current capability of the regulator. Without it, the current is limited by what the op-amp can deliver. Put simply, the Q1 NPN is a high-current voltage ...
hacktastical's user avatar
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6 votes

What is the purpose of the BJT in this circuit?

Diode Z1 is producing a fixed potential, which for argument's sake, let's call \$V_{REF}=+3V\$. This will be used as a reference to control the output potential \$V_{OUT}\$. You might use only the op-...
Simon Fitch's user avatar
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18 votes

What is the purpose of the BJT in this circuit?

Hmm. Okay. Let's redraw the schematic. Perhaps that will help you think about it: simulate this circuit – Schematic created using CircuitLab That should get you started. Just think about each ...
periblepsis's user avatar
17 votes

What is the purpose of the BJT in this circuit?

Suggestion Since this is homework, you will have to make an effort to understand this famous circuit solution. Okay, let's do it this way: I have broken down the sterile university schematic into ...
Circuit fantasist's user avatar
1 vote

Help with a circuit analysis problem

The pMOS pull-up is connected via a C2, a 35 femto Farad cap. When M1 turns on, the cap is charged up to 800mV with a tiny bit of current through that 100 ohm pull-down. But we will see this only once....
hacktastical's user avatar
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1 vote
Accepted

Need help with identifying a SMD part

It's a ETA Solutions ETA1036V50S2F DC-DC converter. (Source: lcsc.com)
nanash1's user avatar
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1 vote

Are inductors in resonant circuits dangerous? They produce very high voltages

It is true that at resonance, voltage across an inductor in a resonant circuit can be large...especially so if resonant components have high Q (quality factor). If one is building a power oscillator, ...
glen_geek's user avatar
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1 vote

Where is the phase shift on this oscillator?

Here is a simulation microcap v12 that shows that this circuit can "oscillate" ... and at what frequency ... Note that I added some "parasitic" components. Serial resistor with ...
Antonio51's user avatar
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3 votes

Are inductors in resonant circuits dangerous? They produce very high voltages

When you touch it, the human body will be adding capacitance to that circuit model, so it will quickly drop out of resonance. Thus, only the small charge in the cap at the time of touch will discharge ...
Aaron's user avatar
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2 votes
Accepted

Will a circuit oscillate at all its resonance modes or only the most dominant one?

Ultimately, an oscillator is a nonlinear dynamical system; which also puts it in the class of chaotic systems. Well-enough behaved oscillators typically exhibit a negative-resistance characteristic ...
Tim Williams's user avatar
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0 votes

Why does this two stage op-amp not work?

You could start by simulating it using discrete devices and ensuring that it works that way: simulate this circuit – Schematic created using CircuitLab V1 is a 0.8Vpp sine wave with 2.5V DC ...
Kuba hasn't forgotten Monica's user avatar
1 vote

Are inductors in resonant circuits dangerous? They produce very high voltages

They can be, just like any circuit that generates high voltages can be dangerous, regardless of if it uses resonance, charge pumps, electromagnetic conversion, etc. Resonance requires specific ...
vir's user avatar
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2 votes
Accepted

How can this Clapp JFET oscillate when its gate is tied to ground at the resonance frequency?

By re-arranging the resonating L's and C's, it may help understand where resonance occurs. The two arrangements shown are electrically equivalent: simulate this circuit – Schematic created ...
glen_geek's user avatar
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1 vote

Driving 2xP-channel MOSFETs with a single N-channel?

Unless you are driving the FETs at a high switching frequency, or the circuit is in an application that is sensitive to very short, very small VHF noise bursts, R3 and R4 are not needed. At first ...
AnalogKid's user avatar
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1 vote

How can this Clapp JFET oscillate when its gate is tied to ground at the resonance frequency?

How does the circuit below oscillate? I have simulated this circuit with microcap v12. Found that it oscillates when the serial resistor (R3 with 100 uH inductor) value is < ~ 30 Ohm. Stability ...
Antonio51's user avatar
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1 vote

How much current will a BJT transistor draw through its base?

There are two primary viewpoints for the BJT: the DC operating point and the AC behavior around that DC operating point. You must keep these ideas totally separate in your mind. The connection between ...
periblepsis's user avatar
6 votes
Accepted

Where is the phase shift on this oscillator?

There's parasitic capacitance in various places of this circuit that can easily make it oscillate, see orange C's in altered drawing: Obviously we get oscillation if we have the \$180^\circ\$ phase ...
Jos Bergervoet's user avatar
2 votes
Accepted

How much current will a BJT transistor draw through its base?

Shouldn't \$i_B\$ be the full current we'd get between base and emitter if we simply had a diode? If it's not, then how do we predict what \$i_B\$ is? It is. But you need to remember that \$V_{BE}\$ ...
Dave Tweed's user avatar
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0 votes

How much current will a BJT transistor draw through its base?

The transistor will draw more current from the base if you disconnect its collector. Yes, the BE junction behaves like a diode but here its cathode follows the anode, so the current is too small. You ...
Circuit fantasist's user avatar
2 votes

Driving 2xP-channel MOSFETs with a single N-channel?

If you ask about R3 and R4, so the main topic is gate resistor. In your schematic, R1 just being a current current reducer, so R3 and R4 will be essentials depends on your design. Edit: it will work ...
Parthenope's user avatar
3 votes
Accepted

Determine the voltages Va and V1 for the circuit

You almost nailed it. All you need to do is to flip the V3 voltage source to get -8V with respect to GND. simulate this circuit – Schematic created using CircuitLab
G36's user avatar
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0 votes

corroded contacts cured with WD40?

WD 40 is a desiccant it does nothing more than remove water which is useful for some types of corrosion. Buffer from all types of corrosion it does nothing you need contact cleaner like deoxit or ...
Voltage Spike's user avatar
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1 vote

Calculating current through a diode in a voltage divider circuit

With resistors, the relationship between voltage across and current through them is well known, Ohms law, \$V=I \times R\$. With diodes (which includes LEDs, of course), this relationship is far more ...
Simon Fitch's user avatar
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1 vote
Accepted

Multiple voltage source problem from Boylestead

The values for Va & Vb you stated are correct for the diagram you drew. If the book does not agree then either the book is incorrect, or you have misstated the question. Perhaps V2 is not a ...
Fabio Barone's user avatar
  • 5,297
1 vote

Transfer function of differential controller

The dc gain for this circuit is zero. So the transfer function is ac only. The reference voltage, \$\phi\$ is ac 0V. So proceed from there. You can include \$\phi\$ in the analysis. It will cancel out ...
RussellH's user avatar
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1 vote

How do we measure inductance with a DC source?

You seem to have been led astray by not considering an appropriate time interval for your plots of current vs time. When 5 V is applied across a 1 uH inductor, the rate of change of current will be 5 ...
Charles B. Cameron's user avatar

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