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Questions tagged [frequency]

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

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The simplest and best way to design a current and voltage protection circuit for this case?

I'm working on a frequency meter project that takes an sinusoidal wave input from a wave generator. The wave is needs to be processed by circuitry that will produce a square wave with the same ...
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24 views

System requirement in frequency domain

Hi Can any one help understanding and interpreting figure 6a and 6b (page 6) in the paper attached down bellow : I need to identify first the transfer function of each plot and then interpret system ...
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48 views

How is it possible to ever have frequency on a DC circuit?

Preface Please read this carefully. I put a lot of time into it and am genuinely attempting to understand. I've read numerous articles about DC and AC circuits and searched numerous places to get ...
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1answer
30 views

Question on the right PWM frequency for Permanent Magnet DC Motors

I know that there are some posts in this site about this question. I don't know if there's a way to find out the "ideal" PWM frequency for motor control. Usually they recommend to be safe in a range ...
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0answers
29 views

Digitally selectable filter for the ST7580

For the ST7580, it uses PSK or FSK to send a signal over power lines. In the design guide the example is designed for an FSK or PSK signal to be transmitted at 80 kHz see page 23 for reference to the ...
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1answer
40 views

Datasheet Notation for Filter Parameters

I've been reading through the LTC1264-High Speed Quad Universal Filter Building Block datasheet but I'm having some trouble deciphering the meaning of some of the variables used in the equations for ...
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1answer
51 views

Maximum switching frequency

Is it possible to calculate maximum switching frequency of IGBT having only datasheet in hands? https://www.semikron.com/dl/service-support/downloads/download/semikron-datasheet-skm200gal173d-...
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2answers
52 views

A question about SPI flash operating frequency

I'm working on a flash chip "W25Q128BV". I get really confused on the operating frequency of this chip. As we can see, "Read Data" instruction is comprised of 3 steps for master: sending opcode, ...
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1answer
32 views

De-rating / Re-rating criteria/theory for frequency in circuit breakers

I'm trying to spec a circuit breaker for a system that will be performing in the 3kHz range, and am not finding much info on how to calculate a new rating based on frequencies in this range (where ...
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0answers
71 views

Rubidium standard mystery output?

I've been playing with a frequency counter (Racal 2202R) that has a built-in rubidium standard. It has two outputs, "Rb OUT 1" and "Rb OUT 2". I could not find any documentation at all, but the ...
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1answer
58 views

Can someone explain how frequency and inductance affects this pair of coupled inductors?

I am simulating this simple circuit on PSIM; a single-phase AC voltage source connected to the primary of a pair of coupled inductors, with a 12 Ohms load on the secondary side. I want to increase the ...
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4answers
2k views

Just how accurate is the frequency of US Wall Outlets? [duplicate]

I have a submersible pump for which I'm trying to determine the variability in flow rate, to high precision. Since this is just an impeller driven by an AC motor, what is the % error in frequency of a ...
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3answers
52 views

Apart from speed, do VSD's also alter current?

As I know it, a VSD alters the frequency to change the speed of a motor. I also understand that since the back emf of the rotor is directly proportional to the speed of the rotor, the slower the motor ...
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2answers
41 views

Overclocking an image sensor for higher FPS

What happens if I overclock an image sensor? For instance the OV7670 (datasheet) which has a rated maximum system clock input (XCLK) of 24 MHz and maximum pixel clock (PCLK) of again 24 MHz. The ...
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2answers
52 views

Is 240V to 24V DC PSU to 120V 60Hz inverter a low cost way to convert 240V 50Hz to 120V 60Hz?

I've been looking at the companies providing step down frequency changing units in the 2000W range, and their enormous size seems to be reflected in an equally enormous price. SO...why can't I just ...
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2answers
36 views

Capturing and replicating IR signals, how to tell frequencies?

I want to capture and replicate IR signals of various electronics. There are various guides out there. However, I realize that there are various carrier frequencies, which I dont see discussed. How ...
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2answers
74 views

How can I convert a pulsed signal to an analog voltage?

I would like to measure the speed of a DC motor using a phototransistor and get as an output a voltage which varies linearly with frequency. The motor speed can vary from 0 to say 3000 RPM. Using the ...
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1answer
19 views

Is it okay to run a Mercury Vapor Lamp of lower wattage (100/150/175W) on a 400W MHL/MVL ballast? Also can a 60Hz ballast be used in 50Hz?

So, I have this RAB BMHH400PSQ Metal Halide Pulse Start Ballast 400W ,M135/M155 MULTI TAP 120-277V with me. Since the MVL are being phased out it has become quite difficult to get a ballast for one of ...
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2answers
53 views

Do I need to consider RF power splitters for signal <1kHz?

I need to tap a signal on a BNC cord to record it with a Labjack ADC. The signal is very low frequency, as the FFT shows. I was planning on using an RF power splitter to add a line to the Labjack. ...
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1answer
38 views

Are these two ways of doing equivalent?

I have two signals sampled at, say, 256 Hz. I want to make the difference between these two signals and downsample them, say until 32 Hz. Is it rigourously the same (in term of final result) to make ...
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2answers
60 views

Calculating the frequency of data lines?

I read a calculation about determining the bandwidth of USB https://www.edn.com/electronics-blogs/all-aboard-/4425691/Rule-of-Thumb--2--Signal-bandwidth-from-clock-frequency Roughly what was said is: ...
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1answer
54 views

Building a series RLC circuit using a given resonant frequency and bandwidth value

Assuming that we have to build a simple series RLC circuit in such a way that the its resonant frequency must be 200 krad/s and its bandwidth as 20 krad/s, we have these components: Resistor: 1000 ...
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3answers
139 views

Can I touch voltage?

After watched this man this man, I have some questions. He touched 170 VDC, what is max DC voltage can I touch when I dry? And wet? What is max AC voltage can I touch when I dry? And wet? Is ...
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0answers
21 views

What is the maximum number of natural frequencies given circuit elements?

I'm learning forced and natural responses, as an exercise the textbook gave 4 scenarios (2R&C, R&2C, 3R&2L, and 2R&C&L) and asked what the largest number of natural frequencies for ...
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24 views

Classifying DFE as highpass or lowpass filter

I am trying to design a high-speed trace link @ 10Gbps for a hobby project. In context of equalizers, I have met someone who called a DFE as highpass filter. It doesn't make any sense to me to ...
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0answers
25 views

Simple implementation of a transistor switch circuit with a given maximum activation frequency

Consider "the transistor switch to control a high-power LED" example at: https://learn.sparkfun.com/tutorials/transistors/applications-i-switches Suppose there is a control circuit that is trying to ...
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2answers
106 views

Having difficulties running AC compressors from a generator on a boat

I have a problem that has me stuck and it’s marine related. When my ship is on shore power the AC system works perfect with no defects the evaporator and compressors comes on. When I switch over to ...
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4answers
211 views

Why can we hear the full range of square waves from 1 Hz-20 kHz, but not sine waves of the same frequencies?

I connected the output (50Ω) of a function generator to a 35 watt 5Ω speaker. When I sent square wave signals of 1 Hz-20 kHz to the speaker, my friends and I were able to hear them. But ...
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1answer
153 views

How does carrier frequency and pulse width modulation in a VFD work together to control AC motor speed?

There is a lot of online information about this but there is also a lot of contradictory information. What is carrier frequency exactly and does it stay the same or does it vary? I understand the ...
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0answers
40 views

How can I find the frequency of oscillation of this sawtooth oscillator circuit?

Simple question: how to find the frequency of oscillation of this circuit? simulate this circuit – Schematic created using CircuitLab My attempt at answering the question is the following: ...
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0answers
54 views

Variable frequency of an astable

I have to make the frequency variable of an square waveform generator built with the help of an astable. I modified a circuit a found on the internet and everything seems good with only one exception: ...
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1answer
112 views

can one increase computing power by reducing frequency and increasing transistors count [closed]

I have had the following idea / opinion in a long time, but I am not sure if it is true. From what I understand, in a processor, coarsely the voltage U required to ...
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2answers
77 views

quartz tuning fork and its series and parallel resonances

Based on the explanation here, I understand that if you electrically drive a tuning fork, you would first see a peak (resonance) and dip (antiresonance). I just tested the frequency response of a ...
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1answer
57 views

How do LoRa end-devices configure their upstream and downstream communication?

I'm in the process of building a LoRa end device, and am also designing protocol. I plan on using the channels specified in the AUS915 ISM Band as outlined in the LoRaWAN regional parameters (though i'...
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2answers
54 views

Behavior of frequency in a sinusoidal circuit

My question is in regards to a circuit like this with a sinusoidal voltage source Vin. When I try to figure out the voltage ratio between Vin and Vout I get ωCR/(ωCR - j). I then try to ...
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1answer
33 views

True near field distance for a short monopole antenna

Antenna properties: Height x Diameter = 3.3 inches x 1.4 inches Test Frequency: 900 MHz (Wavelength = 33 cm or 13 inches) I see some conflicting formulas to calculate the near field distance for ...
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1answer
49 views

RF Combiner Losses

I'm having a hard time understanding what is actually achievable with an RF combiner. Let's consider this scenario, here port 1 of the RF combiner has a sinusoid at f1=100Hz and port 2 has a sinusoid ...
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1answer
52 views

Bode plot graph: Frequency vs. Angular frequency

I am wondering, why are some Bode plots made with \$f\$ or frequency of signal representing x-axis, and why other Bode plots use \$\omega\$ or angular frequency of signal representing x-axis? Why don'...
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1answer
74 views

What frequency do BLDC motors generate?

When BLDC motor is used as generator, how does the amount of poles effect the frequency of the 3 phase AC that it generates? For example, if I had a motor with 8 poles and I spun it at 50 rpm, what ...
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2answers
53 views

high frequency vs low frequency lock-in regarding signal to noise ratio

I understand that the lock-in technique came about in an effort to improve signal to noise ratio. There are lock-in amplifiers operating in high and low frequency regimes. In the context of signal ...
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3answers
132 views

how to make a square wave 1kHz circuit [duplicate]

i want to make a 5V oscillator that has a frequency of 1khz. it will basically go to 5V (HIGH) and then 0 V (low) in a frequency of 1khz with 50% duty cycle.
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1answer
44 views

Is it not recommendable to use a spectrum analyzer in its limit frequencies?

Suppose we have a spectrum analyzer whose range of frequencies goes from \$x \ \mathrm{Hz}\$ to \$y \ \mathrm{Hz}\$. Is there any problem that could arise from measuring signals that are near those ...
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4answers
70 views

What stabilizes the alternators/generators?

I've completed my intern in hydroelectric power plants. I've seen large generators working to maintain voltage in 50Hz. They were turning at 187,5 rpm with 32 poles. But I wondered what stabilizes ...
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1answer
33 views

Harmonic mixing in spectrum analyzers

I'm having a pretty difficult time understanding how tuning works when using harmonics in spectrum analyzers. I'm reading about the topic from Keysight's AN 150. Question 1 The following plot is ...
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2answers
74 views

How do multiple mixing stages work in a spectrum analyzer?

I'm reading about spectrum analyzers from Keysight's AN 150. On page 12 they explain how multiple mixing stages are used to obtain narrower IF filters. The block diagram offered is the following one: ...
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2answers
52 views

Phase noise in spectrum analyzers

I'm reading about spectrum analyzers from Keysight's AN 150 and I have two questions regarding phase noise. The AN states: No oscillator is perfectly stable. Even though we may not be able to see ...
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3answers
1k views

Why do spectrum analyzers use envelope detectors?

Spectrum analyzers can usually be represented by the following block diagram: Before entering the video filter, the signal passes through an envelope detector. What I don't understand is why this is ...
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2answers
60 views

VCO from a rectangular and triangular signal generator

I need to create the simplest rectangular and triangular signal VCO I can using op amps. The output frequency should be changeable between 1k and 15k. I should also be able to change the amplitude of ...
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0answers
72 views

Why is there an inductor sort of a thing inside this antenna?

I have a 20cm antenna exactly of the same shape as shown in figure. I want to know why is there a inductor sort of a shape in its monopole? What is its purpose? Does it affects its designed frequency? ...
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2answers
47 views

Period Measurement

I am reading a book about the measurement in communications. There are a lot of information about how to measure frequency and period of signals. OK, i have understood that we should measure the ...