# Tag Info

### How does this PNP transistor and P-channel MOSFET circuit work?

First consider the circuit without Q4. What remains is Q2, R1 and R2: simulate this circuit – Schematic created using CircuitLab With Q2 being a P-channel device, gate potential ($V_C$ at ...
1 vote

### What do I need to power a Christmas village with mains instead of batteries and in a single circuit?

If you use that circuit what will happen when you turn any of the potentiometers all the way down is the power supply will be shorted out and the pot will likely burn up. The wipers are connected to ...

### How does this PNP transistor and P-channel MOSFET circuit work?

Arranging the circuit so as to be more understandable and easier to analyze, although constants are missing, from an analysis by inspection I obtain:

### How does this PNP transistor and P-channel MOSFET circuit work?

AS already pointed out, it is a "current" source ... unless R3 < 200 Ohm. The current value is ~ 10/160 = 0.0625 A.

### How does this PNP transistor and P-channel MOSFET circuit work?

It's a current source. The wire from the drain to GND is virtually a short circuit, but it's current is limited to 0,6V/R1. I bet it would often be more useful to have some load instead of a wire. But ...

### How does this PNP transistor and P-channel MOSFET circuit work?

In principle, it is nothing else than a classical amplifier stage in common-emitter configuration - however, with a pretty uncommon feedback circuitry, controlled by the collector voltage.

### Multiple Resistors for Rf in Op-Amp

Yes, if you are using the feedback equations you can consider the resistors in series to be the same resistance.

### How to find the tolerance on the output of an op amp circuit?

Sensitivity study for parametric variations. (Idea from the text "Linear and nonlinear circuits" by - Leon O. Chua, Charles Desoer, Ernest T. S. Kuh - McGraw-Hill:
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### NPN Transistor Base Current Calculation from Beta, Vth, and Rth

I'll write up something for you -- a problem and a solution. I'll make it tricky, but real. In fact, I just posted up this schematic a day or two ago. So it is fresh in mind. It may look like it ...
1 vote
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### LTSpice (Berkeley Spice) Files. WHERE?

You get the models from either the manufacturer or another party that has modeled the device. It is possible in LTspice IV to create a new symbol from scratch for a third-party model but who has the ...
1 vote

### LTSpice (Berkeley Spice) Files. WHERE?

Tracking down and integrating SPICE models into a simulation is usually a bit of an adventure. There are many SPICE dialects and no standard. The model files are often proprietary and cannot legally ...

### How do I compute $y_{12}$ in this circuit?

In every good text on the analysis of electricity networks, there is at least one chapter relating to quadripoles. Y parameters are also considered shorted parameters.

### What do we mean by bilateral in two-port theory?

In every good text on the analysis of electrical networks there is at least one chapter relating to quadripoles. In the case in question we have: To understand this further, we make the assumption ...
1 vote
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### Multisim simulation insight

If "j * omega" ... is an inductance ... And 4*V is a "step generator" ... Then I could write these equations: Made with Maple ... i1 (left-high loop), i2 (left low loop), i3 (right ...

### How to find the tolerance on the output of an op amp circuit?

I always start by including the error terms in the schematic. I believe that it looks like this. Then people can follow your equations easier. Unless you are using an exotic opamp, or your closed loop ...
1 vote

### How does this BJT monostable one-shot work?

In the quiescent state, assume Q1 is OFF and Q2 is ON. I would have been a little more descriptive. Assuming Q1's base doesn't draw much, it's base sits at $1\:\text{V}$ due to the divider. Assume \...

### How does AC work with dry cell batteries?

I don't think the batteries were significant in this perverse application. Whoever was observing this was probably not an engineer. Batteries were a part of some standard old-school telephones, wired ...
1 vote

### How does AC work with dry cell batteries?

Your assumption that the batteries would be connected positive terminal to positive terminal (or negative to negative terminal) is incorrect. As you've found, that does nothing for you. It doesn't ...
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### Two-port network

To simplify, I transformed the Y parameters into Z parameters and calculated the voltage gain as follows:
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### Find Thevenin's voltage

In comments you asked, Would it be possible to further simplify this circuit? You can further simplify this circuit by removing the voltage source and resistor, leaving just the current source. Any ...

### RLC circuit with a step DC source connected to it

The series circuit about has α <$ω_0$ which means it is underdamped. It is underdamped ($\zeta = 0.8$) but significantly, you thought that its response will be far more underdamped than what ...
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### Small circuits schematics that can teach you something

You need a copy of the old National Semiconductor Quadzilla applications pamphlet. It has a great collection of circuits and descriptions. And the National Linear Applications data book. Both are ...

### How do I compute $y_{12}$ in this circuit?

Some guidance Y12 tells how output voltage affects the input current. This circuit has Y12=0 because you'll find that Ii=Vi/input impedance. You need only to make a normal circuit analysis equation ...

### Can I wire a 460V three phase heater (Modine model HE150) to my single phase 220V residential service?

The 460V model effectively has three heating elements, each connected between two phase conductors, delivering 50,000BTU/h when 460V is applied across them. Using $P=V^2/R$ you can see that if you ...
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### Algorithm for substituting any resistance network to one resistance

It's a variant of a bridge circuit. simulate this circuit – Schematic created using CircuitLab Algorithmically, you can repeat these steps until reduction is achieved: Find series equivalents ...
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### Algorithm for substituting any resistance network to one resistance

Personally I’d do it the good old “inspection route”: The upper right triangle reduces to 10Ω equivalent. The upper left triangle reduces to 30||60Ω=20Ω. Now we’re left with 10||(20+20)Ω=8Ω. That’s ...
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### Algorithm for substituting any resistance network to one resistance

Some may say, there is no common approach but there must at least be algorithm since computers can do the job all the time. More than a few ways. But time for just one. Since you bring up that ...
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### Balanced vs differential signals

This is my view of the problem According to the electromagnetic theory of guided TEM waves: the current flowing at the surface of the central conductor and that at the inner surface of the shielding ...
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### Use nodal analysis to find Vo in the circuit of Fig. 3.72

Call the bottom node ground. Then the node at the intersection of those three resistors is $v_o$. Call the node with the $3\:\text{A}$ current source entering it as $v_x$. Then in super-node ...

### Parallel LED connection break

You can take out ground from 2 points one from the end of the 10 leds and one form the middle i.e 5 leds and connect them respectively to the NC and NO pins of the switch while the middle pin of the ...
1 vote

### In the circuit of Fig. 3.49, current i1 is: (a) 4 A (b) 3 A (c) 2 A (d) 1 A

By finding the voltage across the current source you can determine the currents i1 & i2. Look up "superposition theorem". It basically states that the voltage at a node of interest is ...
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### In the circuit of Fig. 3.49, current i1 is: (a) 4 A (b) 3 A (c) 2 A (d) 1 A

There are three unknown values in the circuit: v, i1 and i2. To solve this, you need to formulate three equations. The two loops would give two equations. Apply KVL in each of these loops to get the ...

### Balanced vs differential signals

Here are some equivalent circuits you may find illustrative: simulate this circuit – Schematic created using CircuitLab Consider for sake of argument, the values of impedances don't matter, ...
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### LED Control Using SPDT Switch

If your LEDs are really rated for 12 Volts, they will include a current-limiting circuit, so you don't need to add an external resistor. A "bare" LED will have a rated forward voltage that ...

### LED Control Using SPDT Switch

Update: As Peter Bennett pointed out, if the LEDs are rated for 12 V the whole resistor thing becomes moot. If you were to be using standard LEDs the following would apply. If you are using two of ...

### How to deal with one inductor coupled with two different inductors?

You can use definition of "coupling circuits" K. Here is an example of such use.

### Signal diode to protect high speed data lines

What's missing in the illustration is the large number of big capacitors between (+)VCC and (-)Gnd. These capacitors are a ...

### Signal diode to protect high speed data lines

The diode to Vcc serves another, similar purpose. It prevents a voltage on the input pin that may exceed the devices absolute maximum ratings, specifically Vin to Vcc, in the case where the device ...
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### Signal diode to protect high speed data lines

If the data line is more than a diodes drop above VCC, or more than a diodes drop below Gnd, then one of these diodes will conduct and strongly clamp any transients without invoking the clamps ...
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### IR emitter circuit not working

There's many reasons they don't work or work poorly. You are transmitting out only the baseband of the IR signal, which looks like NEC protocol. More specifically, it looks like Extended NEC protocol ...
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### Need help identifying component on circuit board

As explained in previous answers it's a diode from Vishay (General semdiconductor logo). However I would say that the package is a SMC (wide aspect). So the corresponding part number for that marking ...
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### How can I solve this dual operational amplifier circuit with nodal analysis?

I have done a complete analysis. I hope the user's request is understandable and satisfactory.
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### Method used for breaking the loop deemed unsuitable

Measuring loop gain by breaking the loop and using a different port seems... peculiar, to say the least. Mind, such a method might garner upvotes when it's well enough written and not manifestly wrong,...

### State-space average model of non-ideal buck converter

i myself struggled with this too. I will show how to derive the equation for a system only containing the ESR resistor for the Inductor and capacitor, as these are the parts bringing some ...
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### Method used for breaking the loop deemed unsuitable

I am not sure if the setup as shown with the 2nd figure works correctly. It is a rather uncommon approch because the test signal is not injected into the opening point. My doubt: The node between R3 ...
1 vote

### Purely resistive transformer circuit

You only need to solve for $M$. From that you can get $k$: $$k=M/\sqrt{L_1 L_2}.$$ As for making $Z_{ab}$ resistive - you'll be solving to make its imaginary part equal to zero. So, per the \\$Z_{...