how you go about this really depends on what you need it for.
it may be best to make a frequency to voltage converter followed by a voltage to frequency converter. because the frequency is so low, it would be cheaper as far as parts count to just hook up a zero crossing detector to a micro controller and use a lookup table to generate the sine wave from PWM.
http://forum.allaboutcircuits.com/showthread.php?t=17123
The final result is to get the Sinewave 5VAC with 80Hz or above.does it need to be clean snewave? i would think a full wave rectifier, chop it at 80Hz, couple it back out to AC. so as others have asked, why do you need 80Hz, whats the application? what's the dependence on the 5vac source?
This statement is very hard to interpret.I wanna to use the transformer to derease the voltage from 200AVC to 5VAC , then find the analog mulitipler IC AD633 before and want to use multiplication to get higher freq then use AC/AC converter to decrease the voltage again
However, I find that the opearating voltage of this IC is too large for me ,
so, any suggested IC has similiar function with lower opearating of AD633?
Can you clarify something? This signal is really in no way related to your line voltage, correct?
This statement is very hard to interpret.
It would be helpful to know:
1. What is the intended use of this waveform?
2. You may mean that you wish to increase the voltage after increasing the frequency. What is the final signal voltage?
3. Is the use of an AD633 absolutely necessary?
You still have not answered the question.
What will the 5v 80Hz be used for? What does it power?
Thanks for your suggestion..LED's are DC devices. using a transformer to step the line voltage down to a lower level and rectifying to DC would make a much better source. Some means has to be used to limit current through the LED's as well. For varying the intensity, pulse width modulation of the current is effective.
Tells us all about the LED's - forward voltage and required current, as well as number to be used.
With all due respect, unless this is an educational exercise, your supervisor doesn't know what he's talking about. You need to tell him, as tactfully as possible, that the simplest solution by far is to convert the 50Hz AC to DC. You will have to do that anyway, regardless of the frequency of the source, because LEDs will only pass current in one direction.Thanks for your suggestion..
However, I have no choice..
my supervisor only need me to increase the freq of the sinewave..
as I know the LED he provide is 20mA with around 3.5V , and he want me to power up around 100 LED...
But now, the main problem is how to increase the freq..
I have no direction..
That's what I was thinking. It's DC with AC superimposed on it, or stated another way, pulsating DC. He probably doesn't really need to filter it for his application.Use 4 diodes as a bridge rectifier, then the LEDs will flash at double the frequency, ie 50Hz -> 100Hz.
And I agree with Ron_H.
80Hz flicker is generally not detectable by the human eye. 50Hz is noticeable and objectionable to some people.Also the human eye will not se any blinking on the LEDs, but a constant light. The 80 Hz may appear somewhat more bright than the 50 Hz, nothing more than that
If he does it, Rube Goldberg will be proud.The traditional way to produce a variable frequency power supply of modest capacity is to use an audio power amp as an oscillator. You can get up to a couple of hundred watts this way quite easily. A wein bridge configuration with a modular power amp is suitable. Power this from your 50Hz supply.