[time-nuts] FE-5680A Mechanical Question

Jim Lux jimlux at earthlink.net
Fri Jan 13 11:37:13 EST 2012


On 1/13/12 8:15 AM, Chris Albertson wrote:
> On Fri, Jan 13, 2012 at 3:19 AM,<EWKehren at aol.com>  wrote:
>> What we know is that you can set the Rb in 7 E-13. Dithering would allow
>> even closer setting, the question is what rate will the Rb accept with out
>> loosing lock or deterioration of the performance. Some one should explore
>> that.  I am still waiting to se some aging. Taking the 10 MHz output and than
>> use an  analog loop and something like a Morion OCXO and you have the best of
>> all.
>> Digitally controlling the Rb will cut the cost of the control loop in half.
>>   For $10 in parts and a PC board for less than $10 using Shera like
>> controller  can be realized. What is needed is some one able to do the PIC.
>> If some one is interested and able, please contact me off list. A low cost
>> GPS or a 1 pps output of a Tbolt be perfect source.
>> Bert Kehren
>
> Don't use a PIC for the prototype.  A desktop PC could work as well
> and everyone here already has one.   Connect the FE5680 to the PC's
> serial port and send commands to adjust it.  The PC also needs to be
> able to read a voltage.   Many already have audio input with 24-bit
> ADC chips.
>

But those audio inputs are almost always AC coupled.

Bringing up a question: Does anyone know of a cheap (<$20ish) USB 
voltage sensor (16 bits or better, ideally)..  I can see one of those 
Atmel USB capable micros (like the one on the Arduino Uno) hooked to a 
dual slope or successive approximation ADC.

There seem to be an amazing number of times that I want something like 
that.  The DATAQ $29 widget is only 10 bits, unfortunately.  A USB 
interface DMM would work nicely, but I haven't found one that's in the 
under $50 price range.




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