sine to square wave conv.

[Bahram]

sine to square wave

hi all,
I need a simple circuit comprised of transistors to convert a sine voltage(eg. 150vac) to square one(also converting the voltage amplitude) for avr microcontroller input.
I really need your help(I'm new to this forum)thanx

 

[xvibe]

sine to square converter

I think that you can solve the problem with a simple zero cross detector.
Try one of the following:
hxxp://electronicdesign.com/Articles/Index.cfm?AD=1&ArticleID=6225
hxxp://www.discovercircuits.com/DJ-Circuits/60hzclk.htm
hxxp://www.google.com and search for zero cross detector circuit

 

[Bahram]

sine to square

dear xvibe,thanx for your help
question: a VCO is needed for converting the voltage amplitude to freq.?

 

[FvM]

square wave

Apparently, xvibe didn't understand your question because of the rather confusing specification. I understand now,
that you're requesting a voltage-to-frequency converter. To use it with a bipolar voltage, you have to apply an input offset.

Because most recent uP have on chip ADC, voltage-to-frequency conversion is a somewhat outdated method. As you
correctly said, a VCO is required as basic building block. Chips as National LM331 can provide a low part count solution.
You'll also find VCO circuits in many manufacturer application notes, e.g. National LM139 data sheet.

 

[xvibe]

square to sine

Ops, i though that it was just sine to square have converter or for frequency metering proposes.

 

[Bahram]

convert sine to square wave

Sorry,It seems that I have to explain myself more clearly!

you know, I want to measure the output frequency of an electronic ballast(or the applied frequency to the lamp ).It means that I have to obtain freq. from the output voltage of the ballast(the lamp voltage).

firstly, I think the voltage which is sine wave should be vonverted to square wave, considering the following:
1.sine to square conversion
2.voltage to freq. conversion
and in the end,the frequency will be measured with the help of a microcontroller!
this project has other parameters to be measured in addition to freq. such as lamp current and lamp crest voltage.

I would be pleased to see your ideas..
many many thanks ....