Circuit to lower Sine wave frequency

[Alfgan]

Hello everyone!

I have a question. Is there a circuit or component or chip that lowers sine wave frequency?
For example I wave a supply of 100Hz 20V sine wave and I need 40Hz 20V sine wave... what circuit or component would make it possible?

Thanks
Have a good day!

[jhpadjustable]

For what purpose?

[ogden]

For example I wave a supply of 100Hz 20V sine wave and I need 40Hz 20V sine wave... what circuit or component would make it possible?

System containing rectifier + inverter would do the job. Not trivial "circuit" at all.

[Alfgan]

I was only interested if it is possible.

[ratatax]

An approximation could be to saturate the sine wave to make it square, then use a flip-flop to divide its frequency by 2 and smooth it to make it look sine again (will probably be a bit dirty though, and it's for signals, not power)

[Twoflower]

Depending on the requirements (power, stability, ...) a motor-generator system would be an option. But with the little information it's not easy to provide a viable solution.

[mikerj]

An approximation could be to saturate the sine wave to make it square, then use a flip-flop to divide its frequency by 2 and smooth it to make it look sine again (will probably be a bit dirty though, and it's for signals, not power)

That would get you 50Hz rather than 40Hz.

Assuming this is to provide power to something then converting the DC and generating a 40HZ AC is likely the only practical way of doing this.  If these were high impedance signals then you could use a mixer along with a fixed 140Hz signal to downconvert the 100Hz to 40Hz, or you could do it with a PLL and fractional N divider.

[rstofer]

Without knowing the load, it isn't even possible to suggest a solution.  It might be fairly easy to do this kind of thing with a phase-locked-loop, at signal levels, and it might be easy to do with a motor-generator, at power levels.  The recitifer-inverter solutions might be fine for power levels.
There is a world of difference between the solutions.

[grifftech]

rectifier, amplifier, MP3 player

[KMoffett]

Just a thought design:
Phase lock loop to multiply 100Hz x 4 for 400Hz. Follow with a digital divide-by-10 for a 40Hz square wave. Through a very narrow 40Hz bandpass filter. Then amplify to need level. 

[Audioguru again]

Many people use a switched capacitor multiple order lowpass filter IC to convert a squarewave to a pretty good sinewave.

[Kleinstein]

One could first set up the frequency (e.g. a via PLL or nonlinear multiplier) and than use that clock to generate a sine from a look up table or the like.
Chances are the amplitude information would get lost.

Another option would be a mixer (or 2) to shift the frequency by a constant amount.

[rstofer]

We still don't have an answer to milliwatts of megawatts.

[Le_Bassiste]

Hello everyone!

I have a question. Is there a circuit or component or chip that lowers sine wave frequency?
For example I wave a supply of 100Hz 20V sine wave and I need 40Hz 20V sine wave... what circuit or component would make it possible?

Thanks
Have a good day!

these circuits are commercially available as "variable frequency drives" for basically all powers from kW to MW.  if you just need a couple of watts, you could use your hifi amplifier. the basic principle is always the same
1. take what you have and rectify / filter it to DC
2. take the DC and power a halfbridge/fullbridge with it
3. control the output of the bridge by applying a control signal of your choice (waveform, frequency, amplitude).
OTOH,
if you want to consistently change input frequencies (that is, 100 Hz to 40 Hz, 500 Hz to 300 Hz and so on)  you could feed the (heavily attenuated) input signal into a device that is called a "harmonizer", something like the old "Ibanez HD1000", or the famous Eventide harmonizers. and then feed it into an amplifier to boost it back to the desired level.

[IconicPCB]

Google Cycloconverter

[soldar]

We still don't have an answer to milliwatts of megawatts.

Not only that but it needs to be clarified whether he is just trying to get 40 Hz or whether the 40 Hz needs to be in sync with the original frequency. Because they are radically different problems.

[Zero999]

Use a fullwave rectifier to get 200Hz, divide it by 5 to get a 5Hz squarewave and pass it through a low pass filter to convert it to a sine wave.

[SparkyFX]

Getting a 40Hz in sync with 100Hz is unfeasible, unless it needs to start synced or so, but then its just as good as  triggering a second source.

[bob91343]

Use an electronic piano keyboard.  The lowest E (on a full keyboard) is close to 40 Hz.

[jeroen79]

I was only interested if it is possible.

Then the answer is "Yes".

But if that is all you want to know and you have no actual application for this then there is little use in coming up with an actual "circuit to lower a sine wave frequency".