Questions tagged [frequency]

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

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18 views

Sequential NAND Based Phase-Frequency Detector output

I'm trying to understand the output of my phase detector only for a pulse that goes from zero to one. here is my schematic: (ref is Clk_ref, and Div is Clk_out, both come from an outside circuit) ...
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41 views

what does phase really mean?

I'm new to EE, and I am reading a text book which says: Phase describes the position of the waveform relative to time 0. The a quiz asks What is the phase shift for a sine wave with the maximum ...
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Question [URGENT] Please help me design an amplifier with the given specifications [closed]

thanks for taking time to look at this question, I need some help with designing an amplifier circuit, it has to be a single stage amplifier, using MOSFETs (Enhancement type) Gain = -5 Power consumer ...
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26 views

comparing between different phase detectors

I implemented two architectures of phase-frequency detectors and I'm interested to compare between them. (I'm open for extra architectures that might solve problems that I'm not discussing here) I'...
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85 views

Phase detection with non-ideal PFD

I'm trying to simulate for Phase Frequency Detector with the following implementation: and inside NAND_PFD: NOTE: the triangles on the right are inverters and not amplifiers. I'm currently ...
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3answers
61 views

approximation of a digital signal using the harmonic

I'm new to EE, still struggling in understanding some basic concepts. I'm reading a book which says about approximation: To make the shape of the analog signal look more like that of a digital signal,...
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29 views

Why phase is the position of the waveform relative to time 0

I was reading a book which says: Phase describes the position of the waveform relative to time 0. It indicates the status of the first cycle. and below is a picture I am a little bit ...
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49 views

why nonperiodic signals still has the concept of frequency?

I'm new to EE from CS background, just a question on nonperiodic signals. I don't understand why nonperiodic signals still has the concept of frequency/frequency domain? The definition is : Period ...
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45 views

Accurate signal reconstruction

While reading through this page I came across following info: "For accurate reconstruction using sin (x)/x interpolation, your oscilloscope should have a sample rate at least 2.5 times the highest ...
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57 views

In general, construction wise, what makes a speaker more or less sensitive to mid tones?

I bought a second hand vintage boombox and the left (full-range/'woofer') speaker has gone so I replaced both speakers with some Sony ones. The Sony ones are taken from of cabinets lying around (the ...
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26 views

What is an equation that will show RF wave characteristics?

I want to show a RF wave on a spherical grid coordinate system. How can I show the RF wave when t = time and y = magnitude? I also want to show curvilinear coordinate transitions of the RF wave ...
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51 views

Frequency compensation of a two-stages class AB amplifier

The author of the book on which I'm studying explains in depth the following "standard" two-stages op-amp: In order to deal with frequency compensation, he models each stage with a transconductance ...
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96 views

Is 1 Hz equal to 1 rotation of a motor shaft?

I'm rather new to the world of electronics but I have been trying to find the frequency of a DC motor. I've found that 1 hz is equal to 1 revolution per second, but does that refer to shaft rotation ...
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584 views

Why would an AC motor heavily shake when driven with certain frequencies?

I have an AC motor from an old TCL 160 Boxford NC Lathe, it has three wires named U V and W. I thought that incorparating the original driver to a modern control interface card would be difficult or ...
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Laptop failure due to constant fluctuation of AC frequency and voltage [closed]

I spend most of time on a boat (not on holiday :/ ) where a huge generator provides electricity. The potential problem is that the output is very dependent of the "mood" of the engine. Sometimes the ...
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162 views

Inconsistency in Values of Laplace Transformed Current when Changing Units

I was trying to convert the units of the following current in Time Domain and Complex Frequency domain (s-domain): $$ i(t)=20\cdot e^{-t}H(t)\,\,\,\,\,\text{[mA,ms]} $$ Where \$\text{[mA, ms]}\$ ...
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93 views

what is this type pulses called?

I was wondering what is this type of pulses is call. Is it a sin wave? I know its the result of sinusoidal pulse modulation. is it considerd a quasi-sin wave? I would like to know the name to ...
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50 views

Power spectral density on the output of frequency modulator?

Is there a formula with which we would be able to calculate the power spectral density on the output of a frequency modulator? The information we know is that we have a receiver working in 180MHz ...
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1answer
71 views

Is it normal to be able to hear a high pitch buzz from devices that are charging?

I have noticed that in ungrounded outlets I am able to hear an almost silent high pitch sound if I plug in earphones into the device being charged. I think this is the 50 Hz electrical signal that I'...
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2answers
61 views

Frequency Sensitive Switch

A legacy product we are making uses this obsolete Frequency Sensitive Switch, Consumer Micro FX-301L. The switch is setup such that it switches on (-12V) at 2000Hz +-100Hz and switches off at 250Hz. ...
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1answer
65 views

Can I generate frequencies faster than 32 MHz with ATTINY85?

I believe I can use the 64 MHz PLL clock with PWM to toggle every cycle and thereby generate a 32 MHz square wave output on an IO pin, right? Is there a trick to generate an even higher frequency (...
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1answer
149 views

Arduino- Duty Cycle Changing When Frequency Is Increasing

I’m currently trying to increase the frequency from a pin from an Arduino using PWM. I’m using the Timer1 library as it has functions to output signals. I connected a push button to my Arduino and ...
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48 views

Complex Amplitudes and Exp'l Increase/Decrease

The following are quotes from a textbook, If S(t) is represented as a rotating phasor, the angular frequency of the phasor can be thought of as velocity at the end of the phasor. In particular ...
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Can sampling rate be a floating point number?

Suppose we have a sampling frequency for a signal of 15.5 samples/sec and we take samples for a period of 7 seconds. This means total samples are 108.5, does this make any sense? Shouldn't the ...
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80 views

If I look at a signal in its frequency domain, are there some guidelines by which I can tell how that signal looks in the time domain?

I was studying the Laplace transform and the Fourier transform, and I can't figure out if there is some intuitive way of finding out how a signal looks in the time domain if we know its frequency ...
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59 views

STM32 simultaneous PWM output with variable frequency and duty cycle

I've been designing a capacitor discharge welding machine for a while, So the working principle is when the button has been pushed, 3 output will initiate simultaneously which 2 of them is variable ...
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103 views

Frequency response of RC circuit

I have here a circuit that I would like to find the transfer function ( call it \$H(jw) )\$ of so that I may map the input voltage (V_in) to the output (V_out) as: $$V_{out} = V_{in} * H(jw):$$ I am ...
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55 views

uC-adjustable harmonic oscillator circuit @100W

I'm looking for a circuit that performs a harmonic oscillation while its resonance frequency can be controlled with a microcontroller (preferably via an analog signal). The circuit has to drive a set ...
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51 views

Interpreting this bode plot

I ran a frequency analysis on a conductive textile I have designed and I am not sure what to make of this bode plot. My background is in textile design, not engineering. Does this make sense to anyone ...
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85 views

What RF frequency can I freely use without a government's permission legally?

So I want to create a transmitter that sends digital signals that have 30 kilometres of range but in my country. Radio transmission without authorisation is only allowed upto 50 metres. I researched ...
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1answer
52 views

How to see Signal frequency and Sampling frequency on the frequency spectrum

If I have a 100 Hz periodic analog signal and let us say it is band limited to 1kHz and I sample it at 3 kHz. If I want to see its frequency spectrum then how to differentiate between the signal ...
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340 views

Capacitor with specific self-resonant frequency?

I have a datasheet that calls for "a 15 pF capacitor with Self-Resonant Frequency in the 1800/1900 MHz range". It then recommends a capacitor (Murata GRM1555C1H150J) that (so far as I can tell) from ...
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109 views

Physical implementation of a band pass filter does not match simulations

I am building a pasive bandpass filter with the band pass between 134MHz and 139MHz. It is a third order eliptic filter, with theoretical attenuation of around 50 dB for the stop band and less than ...
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66 views

Will this High Frequency AC Signal Generator Circuit work?

I am going to make a variable DC to AC (10-100kHz). The circuit controlled by 2 PWM Signal from microcontroller to drive NMosfet connected to pull signal from two Ferrite core Transformer primary ...
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42 views

Trying to find value of two capacitors using resonant frequencies in three conditions, but wrong formula is derived

I was trying to find capacitance of two capacitors in the following way. Connect each capacitor individually to a same inductor and find resonant frequency in each case. Connect the same capacitors ...
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1answer
30 views

MOSFET channel length

Good day, If you look on google for ARF446/447 in the datasheet you won't find the channel length (in micrometers). I need it to calculate the unity gain cutoff frequency. Also in the case of IRFP360 ...
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1answer
94 views

IRF520 max frequency

I'm having trouble supplying 300mA to an led COB using an IRF520 MOSFET as PMW, controlled with arduino nano. What is the maximum Frequency, in which I can turn the led on and off in this setting? ...
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73 views

Video clocking: crystal or generator?

The video processor (VDP) has 6*Fsc (21,47727 MHz) clock inputs, pins XTAL1 and XTAL2, which is inversion of XTAL1. Present circuit is built using quartz oscillator of above mentioned frequency, and ...
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58 views

Phase, Frequency and Laplace transform

I have a doubt on the relationship between phase and frequency. We know that the definition of angular frequency is: ω(t) = d(\$phi\$(t) / dt, where \$phi\$(t) is the istantaneous phase of our ...
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64 views

PLL (Phase Locked Loop)

I find a bit of confusion on the web about the use of the PLL. Sometimes I read that, given a certain input signal, it is used to generate a signal whose frequency is N times that od the input one, ...
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1answer
86 views

How to design a contactless mechanical shaker [closed]

I am trying to design a circuit to make an inductor oscillate with high-current (around 50A) at a low frequency. The inductor will act as a high-powered electromagnet. Most designs I've worked/messed ...
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1answer
88 views

1/4 wave monopole PCB antenna design

I followed the below procedure to design a 700MHz 1/4 wave monopole PCB antenna. Is this correct? ...
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1answer
46 views

Admittance, Conductance, Susceptance definition

Admittance is the reciprocal of impedance. But: 1) Susceptance is the reciprocal of reactance, or the imaginary part of admittance ? 2) Conductance is the reciprocal of resistance, or the real part ...
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41 views

FCC EIRP test results different than other countries

We have an issue with regulatory testing where our lab reported EIRP varies significantly between separate labs who have tested for FCC and another country. The test methods are quite different. The ...
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2answers
58 views

Implications of dynamic frequency scaling in an embedded system

Dynamic frequency scaling is used to increase or decrease the speed of a processor to conserve power, heat, etc. I've seen my own processor fluctuate between 3GHz and 3.5GHz. What are the ...
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76 views

Frequency comparator circuit in LTspice not outputting expected state

I'm trying to simulate the circuit in the method shown here in LTspice as: I use the same parts 74HCT74 and 74HCT00. But the circuit does not function. Here I set F2>F1 and the outputs at R1 and R2 ...
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41 views

How to choose an antenna for an FM transmitter? [duplicate]

Ok guys I can't understand something. Say that I have this circuit: Assuming that I apply at the antenna 5V, how can I calculate how much power I will trasmit? I found on internet that the current ...
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1answer
44 views

demagnetising a magnet with a high frequency transformer

This is a theoretical question. Some elements described in the problem may be impossible/impractical, but I am just trying to understand the principles. It is kind of a physics question, but also ...
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65 views

How to transmit a signal to a point [closed]

I have a signal generator (Digital Dual Channel Funktion Signal Generator) and want to generate two signals (530 and 550 Khz signal) and want to transmit these generated signals to the points on a ...
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175 views

How do we define resonant frequency for a circuit, that has arbitrary combination of resistors,capacitors and inductors?

How do we define resonant frequency that has arbitrary combination of resistors,capacitors and inductors? For instance inductors and capacitors may neither be in series or parallel, but may ...