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Accepted

If ESR for a capacitor is not given, can you use f, C, and Q to calculate it?

Yes, these are correct definitions, in as much as is shown/used. Keep in mind the complete definition of ESR: it's effective because it varies with frequency. DF is normally measured at low ...
• 39.7k

Inductor and capacitor in parallel should not yield resultant current in phase w/ voltage

Not totally wrong but deceptive, as a reader might think that the inductive load is an inductor. Maybe it is more clear when in context.
• 755
1 vote
Accepted

Inductor and capacitor in parallel should not yield resultant current in phase w/ voltage

"Inductive load" here means a load with an overall inductive component to its current in addition to any in-phase current, not a purely inductive load. I.e. a phase angle between 0 and +90. ...
• 20.3k

Using ceramic capacitors instead of electrolytic capacitors

Ceramic capacitors of that value and size (or, especially, smaller) change value with voltage, are temperature-sensitive and age quite a bit compared to electrolytic capacitors. Here is a simulation ...
• 407k

• 39k
1 vote

Why does the reciprocal of sum of reciprocals relationship appear commonly?

It appears in many contexts, as it's the sum of the harmonic mean of the elements, one of the ways of finding the "most normal value" of a set of values. Typically it's used for rates, such ...
• 15k
Accepted

How is the reactance of a capacitor formulated?

The math Consider this linear differential equation with real coefficients $$\frac{\text{d}\ y(t)}{\text{d}t} + a_0y(t) = b_0x(t) \tag1$$ Assume now that the input and output are complex valued ...
• 4,145

How is the reactance of a capacitor formulated?

How exactly does the reactance formula Xc=1ωC come about? $\mathbb{V}=V_0\exp\left(j\,\omega t\right)$. (Note: The vector length is unchanging. It's tip forms a helix traveling in time. A voltage ...
• 11.2k
1 vote

What are the functions of these capacitors connected to the output of a efuse?

The boost converter TPS61085 has Cout recommendations. 2x10uF is recommended as usually working well. The loop response is dependent on Cout as well as feedback components, but those relationships ...
• 154
1 vote

How is the reactance of a capacitor formulated?

In an ideal capacitor, there are no parasitic resistances so the real component to the impedance is just zero and the phase angle is -90 degrees or -j. It can also be written as Z = 0 - jωC. In real ...
• 20.3k

What are the functions of these capacitors connected to the output of a efuse?

C5-C6 as well. Or, you could equally well ask: why are C3 and C4 equal here? The topic is PDN (power distribution network) analysis, and I won't go into detail here (as hard as that may be to believe,...
• 39.7k

Power IR2110 from a low voltage AC Source

You have connected your "DC Output" of the bridge to the AC input. The cathodes of D1 and D2 are the positive output of the bridge, and anodes of D3 and D4 are the negative output of the ...
• 59.9k
1 vote
Accepted

capacitive filtering of power line transients without power loss

Well, without any detail of what device is in question, or applicable patents if any, there are two typical possibilities. First, consider the equivalent circuit used to test surge: simulate this ...
• 39.7k
1 vote

capacitive filtering of power line transients without power loss

An ideal capacitor is has only reactance and no resistance. So the ideal capacitor is only an energy storage device, rather than energy dissipative. So when considering "active power" (aka &...
• 335

Are variable capacitors compatible with breadboards still available?

You can purchase adapter boards that have 0.1" spaced holes for headers and SMT pads. It should not be too difficult to fit an SMT variable capacitor onto such a board, for example one designed ...
• 407k
Accepted

Are variable capacitors compatible with breadboards still available?

Variable capacitors are used less, since the preference is for digital adjustment. I see variable capacitors all over the place. How do you think VCOs are tuned? They're usually electronically ...
• 96.8k

DC bias vs AC voltage change rate on MLCC capacitors

Prerequisites: calculus, derivatives; E&M, static fields; definition of capacitance. Consider the construction of a capacitor: We have two parallel plates (or anything equivalent to them: a roll, ...
• 39.7k
Accepted

DC bias vs AC voltage change rate on MLCC capacitors

You seem to be interpreting the results without considering the test conditions. Let's start with DC bias test. The website says the capacitance vs DC bias is measured with 0.5VRMS AC signal (...
• 159k
Accepted

Unable to use a MOSFET to connect two capacitors in series

The transistor has no DC bias. The source and drain need a path for DC current but the capacitors block DC. You could add some resistors across the capacitors to bias the transistor. The resistor ...
• 25.1k
Accepted

What type of cap would you use to block DC on a microphone-level audio line (unbalanced)?

You need to know the frequency range you want and input impedance. If this related to the radio of your previous question, then the following is true: The mic input has 8 VDC bias supply and the unit ...
• 159k

What type of cap would you use to block DC on a microphone-level audio line (unbalanced)?

Film capacitors are not microphonic and do not vary their value with applied volts, in other words they are linear. Polystyrene capacitors are good and expensive but I have not needed to use them. ...
• 15.2k

Why are there capacitors in series in this AC/DC converter?

There are circuits where components are doubled for safety and/or reliability. For example, Dubai developed high-reliability LED lamps that need not be replaced for the life of the fixture. Notice ...
• 4,667

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 ...
Accepted

Confusion in deciding a voltage regulator's input output capacitor types

The data sheet does not state what properties of the capacitor are important and in what range they should be. Having said that, many older linear regulator data sheets recommend tantalum capacitors ...
• 159k

Solid polymer electrolytic capacitor storage reliability

Short answer: Yes, it degrades and it will impact service life negatively. Longer answer: First of all: It all depends on the timeframes we're talking about. 10 years, 100 years? But less than a ...
• 3,539

How to define the initial charge of a capacitor in SPICE

For a capacitor you can simply do, in the field of the cap value something like this: 1u, IC=3 and this appears to work. But not for an inductor, for some reason...
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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 ...
• 39k
1 vote

Do I need an input capacitor for a switching voltage regulator, if I already have electrolytic capacitors?

Yes you need a quality capacitor. Bulk decoupling will not likely work due to a the voltage drop across the capacitor's ESR, and even if it does it will almost certainly radiate badly failing any EMC ...
• 616

Do I need an input capacitor for a switching voltage regulator, if I already have electrolytic capacitors?

Datasheet for ti.com LMR54406 page 21 - 8.2.2.5 Input Capacitor Selection describes the input capacitor requirement. I'd summarize the requirements in this order of importance: Ceramic (MLCC) Low ESR,...
• 14.9k
Accepted

Do I need an input capacitor for a switching voltage regulator, if I already have electrolytic capacitors?

Yes. You need the 10uF input capacitor. There is no way even the three (random) electrolytics can handle the job of the input cap, you likely cannot even place the nearest electrolytic as close to the ...
• 159k

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 ...
• 35.2k

RF ground capacitor broken off on Raspberry Pi 4 - How does it affect performance?

Traces crossing a slot or opening in ground plane, is a great way to create an antenna. It's likely these are small value capacitors (a few pF) to adjust the tuning of the slot antenna. It may still ...
• 39.7k
1 vote

how does ESR change as dielectric barrier increases?

ESR due to conductors remains constant, or nearly so: note that, in a practical capacitor, the electrodes being farther apart means more distance from the common points to individual electrodes. ...
• 39.7k
1 vote
Accepted

how does ESR change as dielectric barrier increases?

No, this would not* change the ESR. The relationship between capacitance and ESR is due to space constraints; you can fit more parallel plates (thus lowering ESR) inside a capacitor when the plates ...
• 35.2k

Can I get the internal resistance of a capacitor from the voltage, capacity, and construction type?

EDIT: most of this answer is wrong when dielectric barrier is small. But I'm leaving it here for history's sake. Skip to the edit below for a better answer Everything I know about capacitors leads me ...

Why does a smaller capacitance equate to a larger voltage drop physically?

Let's make an analogy to two glasses of milk. They both have the same height, H. The base of glass A has an area of its base of A1. The area of glass B is B1=2A1. So to fill glass B to height H ...
• 17k

Why does a smaller capacitance equate to a larger voltage drop physically?

I was in the same loop of question. But I realized that voltage source is not equal to voltage drop. Voltage drop is the difference between 2 points of voltage. If I have 10 and it became 7 then the ...

Potentiometer for Kitchen Fan

Cheap speed control modules for fans are typically built around a capacitor that will form an impedance divider, with a purely reactive impedance. So it will reduce the voltage seen by the motor, but ...
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 ...
• 1,600
1 vote

Understanding taser circuit with MOSFET and push pull transformer

This is not a push pull voltage converter. The topology is called flyback. The integrated simulator CircuitLab can at least show the operation of the first part of your schematic. The MOSTFET gate ...
• 7,327
1 vote

Understanding taser circuit with MOSFET and push pull transformer

This is a self-oscillating circuit. First ignore the NPN transistor. When the input voltage Vin is greater than the Vth of the MOSFET, the dot side of the transformer (the lower one on the left side) ...
• 51