Questions tagged [frequency]
How many times something happens per second, measured in Hz (hertz).
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Serbia, Kosovo power grid row delays European clocks. Why?
According to this article (and a lot more published today on the same topic), Kosovo electricity net production balance has decreased during the last weeks.
This has led to a small deviation of the ...
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What's special about 14.31818 MHz?
While desoldering useful components off of old computer hardware, I found quite a large number of 14.31818 MHz crystals.
This seemed odd to me. Why use such an irregular frequency with a very ...
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Why do utility companies supply at a frequency of either 50/60 Hz?
It just struck me that Utility Companies world-wide supply domestic users at either 50/60Hz. It could have been selected to be 10 Hz, or 100 Hz ... whatever
Was 50/60 chosen at random? Is there some ...
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Why does a faster clock require more power?
If you overclock a microcontroller, it gets hot.
If you overclock a microcontroller, it needs more voltage.
In some abstract way it makes sense: it is doing more computation, so it needs more energy ...
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How did 455 kHz end up being a commonly used IF (intermediate frequency)?
Of all possible IF frequencies, why did so many consumer radio and amateur HF radio manufacturers (and filter component vendors, etc.) end up converging on 455 kHz as the IF frequency, from the vacuum ...
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Negative frequencies: what is that?
I know that when the frequency is 0, the voltage will be pure DC. But in DSP and Digital Communication, I have seen mentioning of negative frequencies which I dont quite understand. For example, like \...
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Can I turn Radio waves into light?
Wikipedia says that the frequency of light is 300 THz.
I've made a radio waves transmitter that transmits about 100 MHz.
If I increase the frequency of the transmitter to 300 THz, will the antenna ...
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Why does 60 Hz mean 60 refreshes and not 120?
A light bulb using alternating current at 60Hz turns on and off 120 times per second but in a monitor 60Hz means 60 refreshes per second.
Why is that? Shouldn't 60Hz mean 120 refreshes?
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How precise is the frequency of the AC electricity network?
If I make a digital clock which first detects the AC frequency roughly (whether it is 50, 60, 100Hz, etc), then uses it as its clock pulse source, how precise would it be? Would it work world wide ...
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Why do power grids tend to operate at low frequencies like 60 Hz and 50 Hz?
I understand that a two-pole AC generator has to rotate at 3600 rpm (60 Hz USA) in order to maintain a 60 Hz frequency and higher frequencies would require these generators to spin even faster which ...
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How to convert AC to DC
I am designing a circuit that needs to output 5VDC @ 1A. I'm trying to use a wall transformer to step the voltage down to 12VAC. The next step is the diode bridge and ripple capacitor.
The ripple ...
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What are 12.000393 MHz crystals used for?
I found them on www.digikey.com, and they're apparently made by different manufacturers, so there must be some use for them. What are they used for?
edit
and why? The 2400 baud modem doesn't offer an ...
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Why do push button telephones use dual-tone for signalling?
Here is a related information from wikipedia:
For touchtone service, the signal is a dual-tone multi-frequency
signaling tone consisting of two simultaneous pure tone sinusoidal
frequencies.
...
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Where do overtones in a 555 generated square wave come from?
I have built a 555 oscillator and connected it to a speaker.
Using an oscilloscope I adjusted the 555 to generate a 2.5kHz square wave.
I then held a microphone up to the speaker and fed the input ...
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Why is the bitrate of infrared smaller than the bitrate of WiFi?
Infrared has a frequency of 300 GHz – 430 THz, while WiFi has a frequency of 2.4 GHz or 5 GHz.
As the frequency of infrared is greater than the frequency of WiFi, the transfer rate (bitrate) of IR ...
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Why do digital scopes sample signals at a higher frequency than required by the sampling theorem?
In the quest for a not so expensive PC scope/logic analyzer, I have found a nice little device it looks very well done and I know it will do the job.
However looking at the specifications, I ...
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Why is a lower switching frequency more efficient?
I'm designing a 10V to 3.3V step-down converter. Looking at the LT8610, the applications example shows two similar circuits that have different switching frequencies.
The Efficiency vs Frequency plot ...
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How can I calibrate a retail digital clock that uses a 32.768 kHz crystal?
SOLVED: SEE BELOW ORIGINAL QUESTION FOR IMPLEMENTED SOLUTION
I have two Sony Dream Machine clocks. They are different models; one seems to use the mains frequency and is keeping its time precisely, ...
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Frequency limitation for homebrew CPUs
While looking into some custom built CPUs I've noticed the frequencies at which they operate are relatively low compared to modern CPUs (in the order of several MHz). Is there an electronics ...
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How does RF anti-jam technology work?
I'm pretty certain that RF jammers work by overpowering the target signal with their own higher powered signal at the same frequency. So the question is, how does anti-jammer technology negate the ...
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How critical are UART frequencies?
I'm going to be using an 8 MHz crystal to run my microcontroller at 16 MIPS (PLL 4x, 2 cycle instructions.) However, 8 MHz doesn't divide into any UART frequencies AFAIK... so how critical are these ...
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If an FM signal has different frequencies, how does the radio receive the signal in a fixed frequency?
If an FM signal has different frequencies according to the modulation, how does the radio receive the signal in a fixed frequency like 103.2 MHz?
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Why doesn't higher frequency mean higher data rate?
My question is very primitive :) I've read multiple articles today and answers here, on Stack Exchange, but still don't understand one thing. Why doesn't frequency itself affect data rate in mobile ...
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Are antennas specified for a certain frequency?
"LTE 868 MHz Antenna" Why does 868 MHz stand for? Are antennas specified for a certain frequency or is it necessary for something like input type? For example, I want to transmit a 40 MHz RF ...
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How is it possible to drive VGA displays at such high pixel clock frequencies?
I'm working on a digital circuit using discrete components to drive a 640x480 VGA display in a 80x30 text mode.
For a 640x480 display, the pixel clock is 25.175MHz, which has a period around 40ns. I ...
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How do you visualize negative Frequency in Time domain ?
In the field of Digital signal processing I have seen people using words
Complex signals and Negative frequencies. For eg. in FFT Spectrum.
Does it really have significant meaning in the time domain ...
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How can over 24 GHz communication be possible?
I read the article Google wants the US' wireless spectrum for balloon-based Internet. It says to use over 24 GHz frequency spectrum for communication.
Is it ever possible to generate that high ...
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Is frequency for dc zero Hz?
We know the frequency of a direct current is zero. The reason is that there is no repetitive pattern.
But I was stumbled when I noticed, why can't that straight line be cut into smaller pieces, and ...
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Characterization of bypass capacitors
I was reading through a few post including Decoupling caps as well as this app note Xilinx Power Distribution Network.
I have a question regarding capacitor values within a power distribution system. ...
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How do power grid systems supply power to new loads coming online?
I know that in a power system there are no energy storage elements. Due to this, as soon as power is generated by the generators it is transmitted to the end user where the power is utilized.
Say a ...
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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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How can a phone wire have multiple frequencies at once?
How can a phone wire have multiple frequencies?
In my Networks Textbook about DSL vs Dial Up it says the following:
The residential telephone line carries both data and traditional telephone signals ...
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Is current with a frequency less than 1 Hz still considered DC?
We had a big argument last night with vague conclusions. Is the current with a frequency less than 1 Hz considered DC?
It would still resemble a wave...
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Frequency ranges that causes a hazard to humans
I hope many people might feel little awkward to see this question. But I feel this is important. Because in my place where I am living I can get a radio (Audio Receiver) very cheaply. I don't know ...
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How do digital function generators generate precise frequencies?
I was designing an electronic circuit that requires precise frequency control when I realized how much I don't know about the frequency synthesis itself.
For example, when I take my low-end 2-channel ...
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How can Arduino send an RF signal at 433 MHz?
I am asking this question primarily to learn.
I have learned that Hz is the number of cycles in one second.
Taking that into consideration I have tried the following examples.
Example 1
...
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How does an AM radio filter out only the desired frequency?
I understand that electromagnetic waves in the air induce an alternating current in the antenna. I also understand how, once you filter the signal to obtain the desired frequency, you can get the ...
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Maximum sample rate of Arduino Duemilanove?
G'day all!
I have an Arduino Duemilanove hanging around spare at the moment and thought I might try a few audio interfacing projects. I'm just wondering what sort of sampling frequency I can achieve ...
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Minimum Switching Frequencies in Boost Converters
Why are switching frequencies for boost converters above the 100kHz range?
If I understand correctly, as the frequency increases from 100kHz upwards, the ripple current that is created from the ...
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How exactly are radio waves produced from a current in a circuit itself?
I am 17, and I am new to electronics, and I've learned everything online and expect to continue to do so with all the resources. I have dug around and can't find concise answers on this question ...
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What is Frequency in electronics?
This has been floating in my mind for a while, everything has a frequency. Like a dc-dc converter, my scope is 100 MHz(i know that's a bandwidth but it has the unit of frequency). I understand that an ...
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Difference between "|Z|" and "Resistance" in capacitor datasheet?
I'm shopping for capacitors, and I expect good capacitor datasheets to have a graph of |Z| (the magnitude of the capacitor's impedance) as a function of frequency.
I was confused when I looked at ...
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MC34063A: Why am I overclocking this chip?
I've decided to get some experience with DC-DC converters and I've obtained an Onsemi MC34063A DC-DC converter. From documentation I've got the datasheet, the AN920 application note and the Excel ...
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mains frequency accuracy worldwide
I like to build a device that needs long term time stability. In germany, one of the best simple clocks use the mains power frequency to obtain a time measure. While the frequency is allowed to change ...
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Can LEDs or optocouplers be used without a resistor if PWM is used?
LEDs are often connected through a resistor and the purpose of this seems to be to lower the voltage across the LED to around 1.8V. Can PWM be used to lower the voltage instead of a resistor? If so, ...
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If capacitors are frequency-dependent resistors, then what are inductors?
I was reading The Art of Electronics 3rd Edition, there it was saying "You can think of capacitors as frequency-dependent resistors."
So in terms of this description, what could inductors be?...
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How can a Cat 5 cable (frequency 100 MHz) transmit 2.5 gigabits/second?
I am a bit confused about this Wikipedia article about Category 5 cables.
It states:
The cable standard provides performance of up to 100 MHz and is suitable for most varieties of Ethernet over ...
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What frequency stability crystal do we need?
We're designing a simple digital clock and using a 32.768 kHz crystal with a frequency stability of 20 ppm (standard off-the-shelf SMT).
We're finding the clock is running fast by about 2.5 minutes ...
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Radio frequencies, what are the limits?
What is the correct range of frequencies for radio waves? Wikipedia's article on radio waves states that all frequencies below 300 GHz are radio waves, while the article on the radio spectrum states ...
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Why aren't ferrite rod antennas used in WiFi?
Does it have something to do with soft ferrite's low coercivity, still not low enough at gigahertz frequencies?
See, I'm putting together high gain receiver antennas and transmitter antennas. Space ...
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