[time-nuts] What is a Time-Nut grade Zero Crossing Circuit?

[SAIDJACK at aol.com]

Hi Bob,
 
since the sine wave is symmetric, you can use a simple LVC type CMOS  
inverter with 1M Ohm resistor from input to output, and a 100nF cap (or the  largest 
COG cap you can find) from the input of the inverter to the sine wave  output.
 
You may also want to load the sine wave output with 50 Ohms, as required by  
the source.
 
This works very well. Don't use a schmitt trigger inverter  though.
 
bye,
Said
 
 
In a message dated 7/30/2008 17:35:46 Pacific Daylight Time,  
bob.paddock at gmail.com writes:


Can  you point me to a Time-Nut grade Zero Crossing
circuit that I can feed a  Actel Igloo FPGA (It doesn't
like sine waves)?

For the sake of  discussion the source signal
is a ThunderBolt at 10 MHz.

The FPGA is  rated to 350 MHz, so no need to have
a 5.0000000000000000 GHz Zero Crossing  circuit. ;-)

The FPGA has several interface styles,
so we are not  limited to just TTL or  CMOS.

Suggestions?





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