# Questions tagged [formula-derivation]

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### Derivation needed

I am using a chip that has the following circuit in it where V_in is inputted on the left and V_out is measured on the right. This circuit is sometimes called the "lumped-element delay lines." I was ...
30 views

### Input Voltage of Comparator (Derivation)

I am trying to derive the voltage Vx, in terms of Vin, C, Cp, Voff, and finite gain Av of the op-amp at the end of phase 1, and then again at the end of phase 2. I am getting thrown by the direct ...
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### Current derivative in RLC circuit

How to find the current derivative(di/dt) at t = 0+ in the first loop?
407 views

### What is generic formula for min and max levels of rectified AC voltage?

For example, if i have 1 phase AC voltage with 1 volt peak level and rectify it., i would get some pulsating voltage V = abs(sin(t+0*pi)). Its minimum is 0 volts ...
48 views

### Derivatives in time and phasor domains do not match

Given that voltage can be represented in the time domain as the following: $$V(t) = \vec{\mathbf{|V|}}\cos{(\omega t + \phi_V)}$$ It can be shown that in the phasor domain, this is the equivalent ...
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### Deriving resonance frequency of RLCC circuit

I am trying to determine the resonance frequency of an RLC resonator with added capacitor, as shown below: simulate this circuit – Schematic created using CircuitLab Two cases are easy to ...
60 views

### Rectangular signal

Can someone explain me how do I take the first derivative of the given function and how will this function look like ?
136 views

### Derivation of LC impedance transformation formula

Apologies in advance for this esoteric question (and source). I've been studying wideband LC oscillators recently and my search for an amplitude stabilized configuration led me to the Vackar ...
3k views

### independent control of frequency and duty cycle in 555 timer (formulas)

I want to control frequency and duty cycle of output pulse of 555 timer. I searched and find this schematic in a post in SOV but I don't know how calculate frequency and duty cycle in the circuit. ...
2k views

### Current draw calculations for a brush-less motor are way off

I've been attempting to calculate how much current a BLDC will draw given a known propeller size, thrust, internal resistance, Kv rating, Supply Voltage(Vin) and idle current. My propeller parameters ...
305 views

### MOSFET Biasing Problems

I am interested in finding Vgs for E-MOSFET for desired Id or/and Vds. Referring to those equations of drain current in saturation region, value of conduction parameter "K" would be nice to have but ...
2k views

### Basic formula for calculating required cable area

Trying to do a spreadsheet to figure out how much cable of different dimensions I will need for a low voltage DC electrical system, but got stuck on the formula for converting current draw, distance ...
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### Calculating Antenna Gain

As far as I understand, and antenna like a simple dipole has a circular radiation pattern at the 2 edges, so the physical aperture in this case is circular. $${A = \pi * r^2}$$ Where r is the ...
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### Relationship of Induction Motor Frequencies

I would like to know how the mechanical rotor frequency [Hz] can be obtained from the electrical stator frequency [Hz]? This is no homework! I have consulted several books as well as the web but could ...
1k views

### How to differ output & input resistance of small-signal model BJT?

I understand how input and output resistance of small-signal model for bipolar transistor is defined and how draw one. What I don't understand quite yet is how actually input and output resistance of ...
74 views

### Mason's Gain Formula with a not connected loops

We have the following path. I tried to create the gain with Mason's formula, which lead me to the following: ...
498 views

### Common Source JFET amplifier input voltage

I want to compare to different formulas which stand for same parameter/value. Here is common source JFET amplifier circuit schematic: Here is the first formula which should apply in general to all ...
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### Where does the formula for Voltage in AC with inductance come from?

This is what the textbook says: I don't understand why does ωLIm equal Vm so if someone knows please explain it to me Thanks
1k views

### What is the origin of the capacitance formula?

Everyone knows capacitance is defined as C = Q/V, but why? Sure I understand the utility of it and its use, but can someone provide a motivation or historical context for this definition? I'm unable ...
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### How to Derive Capacitive- and Inductive Reactance Formula

I've been searching around the internet to find out how to derive the reactance formula for capacitors and inductors. But I couldn't really find anything, so I thought why not make a post about it. ...
So the formula for charging a capacitor is: $$v_c(t) = V_s(1 - exp^{(-t/\tau)})$$ Where $V_s$ is the charge voltage and $v_c(t)$ the voltage over the capacitor. If I want to derive this formula ...