Questions tagged [frequency]

How many times something happens per second, measured in Hz (Hertz).

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2answers
44 views

Why does the \$ Q\$-factor depend on the resonant frequency?

The \$Q\$-factor is defined as $$Q=\frac{\omega_{0}}{\Delta \omega},$$ where \$ \Delta \omega\$ is the bandwidth around the resonant frequency \$ \omega _{0}\$. For a series RLC circuit, $$\Delta \...
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0answers
31 views

TCXO with tune-able Frequency

Hello I need a TCXO with tunable frequency 10 to 12MHz. I find the part here A18ST but this company is not responding and I don't find their distributors. Please help me if anyone knows a company that ...
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0answers
46 views

Confusion with the meaning of the terms for this pulse train output device

I cannot find an online manual but there is a device which is outputting voltage pulse train with respect to its rotation speed(a windmeter). Normally the frequency of the pulses are read and ...
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1answer
21 views

Switching Frequency for Flyback Quasi Resonant Converter

As I know, the major difference between normal flyback converter & flyback quasi resonant converter is for flyback quasi resonant converter, the switching frequency is variable. This means that ...
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3answers
52 views

What is the typical delay relative to to the maximum delay?

I have a board with a number of ICs, an FPGA, and some flash and RAM devices. The board is designed based on worst case conditions, as it should be. The critical combinatoric path has a maximum ...
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1answer
59 views

Designing a frequency detection circuit [closed]

Hi i was wondering if its possible to make a digital frequency detection signal which detects which generation is being used by nearby mobile phone ie:gsm 3g 4g the frequency band varies according ...
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2answers
67 views

Frequency compensation and feedback capacitance

I was reading the chapter of Microelectronic Circuits (Sedra Smith) about negative feedback systems, and it shows an example of Miller frequency compensation with the capacitance Cf shown in the ...
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1answer
95 views

How can I add (kHz to MHz) high voltage signal to a high voltage DC offset?

I am working with MEMS structures and need to move a device (switch) in a operating point with quite high offset. (150V DC offset and a voltage swing of 60V) To generate the high HF Voltage (up to ...
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2answers
29 views

Antenna Tuning for a Multi-band Antenna

I have PCB antenna . which support multiple band antenna. https://www.johansontechnology.com/datasheets/0830AT54A2200/0830AT54A2200.pdf we also have tune circuit before antenna as recommended by ...
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2answers
1k views

How many watts does a 40 MHz radio frequency signal create?

I am new to the study of electromagnetic frequencies and electrical engineering as a whole. I am trying to understand how to convert a radio frequency into energy, or calculate the power density of ...
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27 views

Based on \$f(f) = \phi_{\beta} \; \land \; f(t) = |\beta_u| \$ determine type of oscillator

Imagine the below characteristics of feedback circuit in sinewave oscillator are drawn: $$f(f) = \phi_{\beta}$$ $$f(t) = |\beta_u|$$ Based on the characteristics, how can I tell: Which type of an ...
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1answer
57 views

Doorbell hack - remote unlock door

We need to use the audio output of a wireless doorbell to trigger a stable DC voltage which is going to keep switched a 3.3V DC relay as long as the audio output is present. The relay is supposed to ...
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19 views

How to connect ADF4153 modem oscillator serially with PC without using SDP board?

I tried to connect ADF4153 modem oscillator with PC using STC15W4K56S4 that I bought from Aliexpress. My PC is reading the modem but the program is not, so I am trying to connect the ADF4153 ...
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1answer
57 views

3-dB frequency of cascaded opamps

We have two identical opamps with a first order low-pass response. They both have the same 3-dB frequency \$f_1\$. I need to show that their combined 3-dB frequency (when they are put in cascade) is: ...
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2answers
55 views

3dB frequency of inverting amplifier

There is already a similar question in this website, but I still can't solve this. I have the following information: An inverting opamp with nominal gain -20V/V, DC gain 10^4 and unit gain 10^6Hz. I ...
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4answers
84 views

Why we need bandwidth with ASK?

Now I know that this question might sound silly, that is because apparently I am missing something here. Basically my question is, if ASK works as on/off keying meaning that provided we have an ...
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0answers
43 views

Why does a circuit with only reactive components have infinite Q factor?

So I came across the statement in my textbook. So I have been trying to understand why this is the case, however I just have not been able to understand
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1answer
46 views

Filters in cascade

Let´s say that in order to avoid having a filter of too large of a degree, I use multiple filters in cascade: Low frequency gain of 8dB Cut-off frequency of 4Hz Chebyshev of order 2 Would the ...
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1answer
50 views

Is noise density over a bandwidth a measure of the noise's standard deviation?

Suppose I have a sensor which has a dominant white gaussian noise source, a \$1\textit{unit}/\sqrt{Hz}\$ noise density and a bandwidth of 100Hz. Then the noise becomes 10\$units\$. Is this a measure ...
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1answer
97 views

What determines generator frequency besides engine RPM? [closed]

I have a 230 V 3-phase generator, which runs at 180 Hz. Can I change the frequency to 60 Hz?
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3answers
100 views

Calculate maximum deviation of quartz crystal

How can I calculate the maximum deviation of a quartz? This is from datasheet (12MHz): Frequency Tolerance at +25° C => +- 30ppm temperature tolerance -20°~ + 70°C => +-50ppm aging (first year) => +...
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1answer
75 views

Why is total harmonic distortion defined in the following manner?

So the total harmonic distortion is defined as $$THD = \sqrt{\frac{V_{2}^2 + V_{3}^2 + V_{4}^2...+V_{n}^2}{V_{1}^2}}$$ which means Total harmonic distortion is defined as the square root of the ...
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0answers
148 views

Multimeter Always Reads 60Hz Measuring a CD4060 Pierce Oscillator

Using a CD4060 IC I’ve built a crystal oscillator circuit similar to the one in the image. I’m trying to use my klein mm400 multimeter to measure the oscillation frequency so I can get a rough ...
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0answers
23 views

Doubts about IIP3 (Third Order Intercept Point)

I was reading the chapter of the book "The Design of CMOS Radio-frequency Integrated Circuits " (Thomas H. Lee) about linearity of power amplifiers. It introduces the definition of IIP3 by saying that ...
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1answer
32 views

Adapters from Australia to Canada [closed]

I am in Australia and going to Canada I have 2 laptops that I want to take with me. and other electical stuff such as shaving machine and electrical teethbrush. I am going to get Canadian plus with ...
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2answers
87 views

Stability of Differentiator Circuit

let's consider a generic differentiator circuit, i.e. a circuit whose transfer function is \$\text{constant}\cdot j\omega\$. For instance, you may consider this circuit with Op-Amp: I was reading ...
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1answer
44 views

How to compute clock cycle time from given frequency

let's say I have a processor runs at 100MHZ frequency how can I compute from this it's clock time for each cycle? I know that Frequency = 1 / Clock Time but I am having trouble to fully understand how ...
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2answers
66 views

Application of Frequency Response Theorem in Linear Circuits

One of the most important results of control theory for linear systems is the so called "Frequency Response Theorem" (here the references): Briefly, it says that under the hypotesis of stability and ...
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1answer
55 views

How do SOCs transmit at a higher speed than the internal clock?

E.g. ESP 32 has an internal clock of 240MHz, but can transmit at 2.4GHz (following 802.11 standard). How is this accomplished? Does it really generates a wave at 2.4GHz frequency? Is it not limited ...
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2answers
66 views

Frequency Domain Analysis with Transistors

I have some doubts about how some circuits with transistors are described in electronics textbooks. Let's see an example (taken from Thomas H.Lee, The Design of CMOS Radio-Frequency Circuits). This ...
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1answer
73 views

Hacking ATM with its aux port [closed]

(I opened a topic about it a few minutes ago but I thought it would be better if I ask my question more properly.) I wonder if is it possible to hacking an ATM (through it's aux port) with connecting ...
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0answers
25 views

Parasitic capacitance of a chip

I know that the parasitic capacitance of a chip is pronounced Cdyn. If I apply on some scenario one the chip which will toggle the all of its transistors with two different voltages, but the frequency ...
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0answers
39 views

The criterias to select peak detector capacitance and resistance [duplicate]

edit: diode is replaced with 1n4148 While designing such a peak detector, what should be the approach of choosing C and R values? Which specs of the detector will be based on them? I assume their ...
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1answer
39 views

Question: AC Voltage and Current variables

So I know how alternating current is produced, but I'm curious to what determines the voltage and amount of current moving within the wire. Does the frequency of the alternations give more voltage/...
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3answers
155 views

Frequency response of this circuit

Im not sure how to find the frequency response (\$H(jw)=V_o/Vin\$) of this circuit Can anybody help please?
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2answers
83 views

How does a microcontroller provide a frequency higher than its crystal frequency? [duplicate]

I have a microcontroller which is connected to an 8MHz crystal. I have a schematic which has a QSPI flash IC connected to it whose clock is provide by the micro and happens to be 48MHz. I want to ...
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1answer
62 views

Frequency Circuit

I have seen this circuit on internet. I would like to understand what its purpose is. It seems to be related to something which is call "jitter." I have done some research about "jitter" and I think ...
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3answers
83 views

Why is the impedance zero at cutoff frequencies in a series RLC resonance circuit?

I see that, in many derivations in the frequency analysis of series RLC circuits, \$X_L - X_c = R\$ or \$Xc - X_L = R\$ is considered at lower and higher cutoff frequencies. So does that mean that the ...
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0answers
32 views

“Trace Max Hold” function in spectrum analyzer

I have seen my professor doing a measurement with the spectrum analyzer in which he wanted to evaluate the frequency response of a bandpass filter. He used a signal generator in sweep mode from 1MHz ...
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1answer
54 views

Low Frequency EMI

I was wondering if low frequency EMI can occur with PWM or other sub MHz signals. I am aware that harmonics of these signals can generate EMI but I was wondering if the fundamental frequency can ...
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1answer
64 views

Ambiguity in the Definition of Resonance Frequency

we know that in a series LC circuit the resonance frequency is defined as that frequency in which the total impedance offered by the circuit is zero. We also know that in a parallel LC circuit the ...
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5answers
132 views

Sampling theorem clarifications

whenever the sampling theorem was explained to me, a situation of this kind was proposed to me. If we look at the previous image we will see that the condition to avoid spectral aliasing is that we ...
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1answer
35 views

Tuning Resonant Cavities

I have seen that some resonant cavities are equipped with some external screws, called tuners, which can be used to vary the resonance frequency. Can you explain me the physical reason with which to ...
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3answers
64 views

How to add value of 5e^(-25/2t)u(t) to a voltage source in LTSpice?

I want add the following value 5e^(-25/2t)u(t) as a Vin to my circuit in LTSpice. However I don't know how to do this - can someone help?
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1answer
124 views

Clock frequency divider circuit (divide by 2) using D flip flop

I was trying to implement frequency divider by 2 using D flip flop with the logic connection of ~Q to D input. I provide 2x clock frequency of 50% Duty cycle in the hardware where D flip flop is made ...
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1answer
31 views

change in ac reading relative to the frequency

I'm working on a school project, just measuring the Vrms of two different waveforms at different frequencies. The function generators output is connected directly into an oscilloscope therefore the ...
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0answers
52 views

In an automotive ECU application for STM32, what ADC modes should I use?

I am writing an application for the STM32f407-Discovery board that will use the ADCs present on it. I want to have access to all 17 of the input channels, and I will be using the HAL library to write ...
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1answer
88 views

Finding frequency of a series of pulses (3 - 60 Hz) without using a microcontroller or frequency-to-voltage converter

I came across an interesting yet challenging problem of finding the frequency of a series of pulses. The pulses can have a frequency anywhere from 1 to more than 100 Hz. The goal is to detect if the ...
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2answers
1k views

Why do most flyback converters / LED drivers operate under 100 kHz?

Most of the LED drivers and flyback converters I have come across operate in the 60-100 kHz range. Is there any particular reason behind this - example - ferrite cores not being able to handle higher ...
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3answers
186 views

How does Laplace transform include the transient response?

When we provide a sinsusoidal input, the evaluation of the solution of the differential equation head-on becomes horrendous. So we give an imaginary, complex exponential input and solve the ...

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