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Analog Frequency Dividers

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walters

Banned
How do i Divide the Frequency?

If i take my function generator output 1K hz what circuit can i build to divide this frequency down or UP?

Oscillators frequencys outputs 440hz how do i divide the oscillators frequency down or UP?
 

_3iMaJ

New Member
If you're using a TTL function you can do it with a counter. It will only allow you to divide by powers of two unless you use some other circuitry. If you're not using a TTL signal then it becomes a bit more complicated. You have to do a sort of mixing on your signals.
 

walters

Banned
Yes i want to use Sine Wave inputs that divide the Sine wave frequency
what circuit would do this?
To divide the Frequency of Sine Waves?

Are Oscillators Frequencys Sine waves?

How do divide the oscillators sine wave frequencys?
 

_3iMaJ

New Member
You have to use what is called a mixer. You multiply the function that you want to change the frequency of by corresponding sine function. For example:

cos(2*pi*w*t)*cos(2*pi*b*t) = k*(cos(2*pi*(w - b)*t) + cos(2*pi*(w+b)*t))

You get the sum and difference frequencies VIA a trig identity.

k is just a constant term. Don't quote me (and with out getting a book) I think k = 1/2.

Good luck.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
walters said:
Frequency Divider Mixer?
Sine wave Divider Mixer?
A 'divider' is generally a digital device, so works with square wave inputs, and outputs a square wave.

Your main problem is you haven't given us any clue what you are trying to do?, so perhaps you should do that first?.

But for a clue to most solutions, think PLL (Phase Locked Loop).
 

walters

Banned
A 'divider' is generally a digital device, so works with square wave inputs, and outputs a square wave.


Are Flip flops analog frequency Dividers?

I'm trying to Divider UP and DOWN the freqency of a Sinewave how do i do this?
 

Nigel Goodwin

Super Moderator
Most Helpful Member
walters said:
A 'divider' is generally a digital device, so works with square wave inputs, and outputs a square wave.


Are Flip flops analog frequency Dividers?
No, it's a digital divider - you don't get analogue dividers.

I'm trying to Divider UP and DOWN the freqency of a Sinewave how do i do this?
You can't 'divide' UP, only 'divide' DOWN.

But again, tell us EXACTLY what you're wanting to do!
 

Pyroandrew

New Member
In the 'pure' view of things you cannot. It is physically impossible. This is because the pure sine wave contains only one frequency component: itself!

However, if you convert the signal to a square waveform (digital signal), you can use counters/dividers/logic to achieve a lower frequency (fractional values only though) square wave. You would then use a low pass filter (possibly with a few stages) to convert the signal back to a sine waveform.
To achieve a higher frequencies you would, once converting to a square wave, use a bandpass filter to isolate the higher frequency component you want, which if done well will produce a good sine waveform. Again, you can only get fractional (well actually integer) values.

What you are trying to do is quite limited. Once you have a square waveform you can get 3x 5x 7x 9x 11x etc. the base frequency, however these will all be of a lower amplitude, as the frequency component’s amplitude decreases as the frequency goes up. As for lower frequencies, you are less limited; you can achieve a quite comprehensive set of values. In all cases you will need to design a different filter for every different output frequency. Again in all cases you need to convert your sine waveform signal to a digital one first, it’s the only way, unless you invent some higher order dimension distorting device.
 

mechie

New Member
Phase Locked Loop

Nigel Goodwin said:
But for a clue to most solutions, think PLL (Phase Locked Loop).
This sounds like the easiest way to go based on your very vague description of what you want.

A phase locked loop would take your main oscillator and make a second oscillator 'lock in' to it, by dividing the main oscillator's output by 2 (easy with a counter) the second oscillator will follow to this new frequency.

This still limits what is possible as far as frequency choice is concerned.
You mention 440 Hz - is this for music ? Do you want to generate semitones ? (there are much better ways to do that).
 

_3iMaJ

New Member
_3iMaJ said:
You have to use what is called a mixer. You multiply the function that you want to change the frequency of by corresponding sine function. For example:

cos(2*pi*w*t)*cos(2*pi*b*t) = k*(cos(2*pi*(w - b)*t) + cos(2*pi*(w+b)*t))

You get the sum and difference frequencies VIA a trig identity.

k is just a constant term. Don't quote me (and with out getting a book) I think k = 1/2.

Good luck.
This is what you need to use, I forgot to mention you need to filter out the component you don't want. It's not exactly a divider or a multiplier, but you can get the frequencies you want with this approach. However, it is very impractical.
 

walters

Banned
So What are the frequency divider circuits called?
I can't find any network circuits that do this because i don't know the
names of them to do a function like this?

So you have to convert Analog signals to digital signals to divide or multiple the frequency?
 

Nigel Goodwin

Super Moderator
Most Helpful Member
walters said:
So What are the frequency divider circuits called?
I can't find any network circuits that do this because i don't know the
names of them to do a function like this?

So you have to convert Analog signals to digital signals to divide or multiple the frequency?
For the THIRD TIME - TELL US WHAT YOU ARE WANTING TO DO!.

If you do that we can offer advice, as it is you're not asking relevent questions!.
 

walters

Banned
I want to take the output of my sinewave generator frequency and
divide it down or up


Sine Wave frequency 1K hz>>>Frequency divider circuit>>>500hz

Sine Wave freq 800hz>>>freq divider circuit>>>400hz


I might have to Convert the Sine wave to a Square wave to divider
or multiple the frequency

What Digital Flip flops,clocks,frequency dividers circuit is there that i can
build to do this?
 

Nigel Goodwin

Super Moderator
Most Helpful Member
walters said:
I want to take the output of my sinewave generator frequency and
divide it down or up


Sine Wave frequency 1K hz>>>Frequency divider circuit>>>500hz

Sine Wave freq 800hz>>>freq divider circuit>>>400hz


I might have to Convert the Sine wave to a Square wave to divider
or multiple the frequency

What Digital Flip flops,clocks,frequency dividers circuit is there that i can
build to do this?
This is still very vague?, if you give precise details you have a chance of getting precise answers, vague details can only get vague answers. You're asking questions on how you think you can do what you want, and not on what you are actually wanting to do!.

But as I posted originally, and as others have, a PLL system will do all you require - but may be overkill?, again it depends what you are trying to do?.
 

walters

Banned
How do i use PPL circuits to do this?

I never used PPL circuits so this is all new to me can your please guide me on how to use these PPL network what i need to do to get these results and functions
 

_3iMaJ

New Member
walters said:
I want to take the output of my sinewave generator frequency and
divide it down or up


Sine Wave frequency 1K hz>>>Frequency divider circuit>>>500hz

Sine Wave freq 800hz>>>freq divider circuit>>>400hz


I might have to Convert the Sine wave to a Square wave to divider
or multiple the frequency

What Digital Flip flops,clocks,frequency dividers circuit is there that i can
build to do this?
You need a mixer and a filter. Its all goverened by the math I posted above.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
walters said:
How do i use PPL circuits to do this?

I never used PPL circuits so this is all new to me can your please guide me on how to use these PPL network what i need to do to get these results and functions
It's PLL (Phase Locked Loop) not PPL.

I can't advise you because you WON'T tell me EXACTLY what you need to do, and it's VERY relevent!. There's no point whatsoever in me guessing what you want, giving you a great long explanation, then finding out it's nothing like what you want anyway!.

If you search for PLL or "Phase Locked Loop" there's plenty of information on the Internet, but there are many ways to use them - which again, is why we need to know!.
 
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