variable voltage

[aymanok]

i have a variable dc volts from 3 to 12 vdc, at high frequency up to 500 khz, square wave form
how can i convert it to ac variable volt?

 

[arvinfx]

RC filter for low current and LC filter for high current

 

[aymanok]

do you have a link for this circuit?

 

[alec_t]

By 'ac' do you mean simply alternating polarity, or do you mean sinusoidal?

 

[aymanok]

simply i have a source of variable dc current i want to convert it to variable ac (source= 3 to 12 volts dc, required corresponding ac volts 3-12 volts ac)

 

[Roff]

Why do you need AC?
Does the AC voltage have to power a load?

 

[alec_t]

If you don't need a sinusoidal waveform you could generate the 'ac' by supplying the squarewave to the input of a suitably biased high speed opamp with a gain of 2.

 

[aymanok]

If you don't need a sinusoidal waveform you could generate the 'ac' by supplying the squarewave to the input of a suitably biased high speed opamp with a gain of 2.

i can generate the square wave

 

[aymanok]

Why do you need AC?
Does the AC voltage have to power a load?

i need ac in another circuit but the source current is variable dc (3 to 12 v dc) i want to convert it to the corresponding (3 to 12 v ac)

 

[Roff]

i need ac in another circuit but the source current is variable dc (3 to 12 v dc) i want to convert it to the corresponding (3 to 12 v ac)

I also asked you this:

Does the AC voltage have to power a load?

If so, how much current does the load require?
Does the AC have to be 3-12V RMS, or can it be 3-12V peak-to-peak?

If you want help, please answer ALL the questions.

 

[alec_t]

...and you still haven't said if the AC needs to be sinusoidal. What level of distortion of a sinusoidal AC waveform would be acceptable?

 

[MikeMl]

If you don't need a sinusoidal waveform you could generate the 'ac' by supplying the squarewave to the input of a suitably biased high speed opamp with a gain of 2.

It is even easier than that. Just generate a square wave of the desired amplitude and frequency using (for example) a 555. Use a dc blocking capacitor between the output of the 555 (pin3) to block the average DC value of the square wave. The resulting wave will be symmetric with respect to ground.

 

[aymanok]

I also asked you this:If so, how much current does the load require?
Does the AC have to be 3-12V RMS, or can it be 3-12V peak-to-peak?

If you want help, please answer ALL the questions.

yes it will work to power load
the load requires 1 amperes current
it requires 3-12 volts peak to peak (the volt measured buy multy meter)

 

[aymanok]

i wan to explain more about that:
the source power = 3-12 v dc
i want to convert it to 3-12 v ac peak-to-peak, current = 1 amp
the generated ac will be stepped up in a transformer up to 220 volts
(the main aim is to get a variable ac from 3 to 12 volts to use as feed to the step up transformer)
* All volts are measured by multimeter

 

[Roff]

Do you require 220V at 1 Amp to the load?

 

[aymanok]

Do you require 220V at 1 Amp to the load?

i want to convert 3 to 12 volt dc to the corresponding current (max. 220 v ac at 12 volt dc)

 

[aymanok]

Do you require 220V at 1 Amp to the load?

i want to convert a variable source 3 to 12 volt dc to the corresponding ac volt

 

[aymanok]

Do you require 220V at 1 Amp to the load?

at 220 volts ac the current = 0.054545 amp as the feed is 12 volt ac at 1 ampere (converted from 12 volts dc)
the dc volt is variable

 

[aymanok]

the converted 12 volts ac is RMS
The load (after step up transformer which will convert 12 ac to 220 ac) requires 0.055 Amp.
the Problem i face is : what circuit can make the (3 to 12 v ac) is variable that i can change the out put transformer voltage)

 

[Roff]

A square wave at 12V peak-to-peak will only give you 6V RMS.
What kind of transformer do you have?
Why do you need 220V at low current?