[time-nuts] Valpey - VF154

David Forbes dforbes at dakotacom.net
Sat May 24 16:16:45 EDT 2008

At 12:42 PM -0700 5/24/08, Randy Leifer wrote:
>I applied 5v + ground to the proper pins. Pin 1 left
>Results vary from part to part, but within 10kHz of
>1MHz.....especially if voltage is dropped to 4.1v.
>3.3v output is further off.
>I don't know if a load on the output makes a
>difference...(load resistor value ? ).
>Scope shows a square wave...but not a pretty one.
>A 10nf cap across the power pins helps freq stability,
>but does nothing to the scope image.
>Is it pointless to attempt to get a good sine wave out
>of this? ...or best to get a real sine wave part ?
>These I'm guessing, are TTL/CMOS type.


Those do sound like old-fashioned TTL oscillators. They will require 
5V to run. Expect a frequency error range of about 50 PPM.

The easy way to get a sine wave is to add a low pass filter. 
Something made out of some resistors and capacitors will produce a 
decent result. You might want to add an amplifier after that.

And don't expect good frequency accuracy or phase noise, since these 
are meant to clock a microprocessor, not provide an accurate 
frequency reference.


--David Forbes, Tucson, AZ

More information about the time-nuts mailing list