[time-nuts] GPSDO Alternatives

Jim Lux jimlux at earthlink.net
Wed Dec 5 12:57:49 UTC 2012

On 12/5/12 12:06 AM, Bruce Griffiths wrote:
> Hal Murray wrote:
>> albertson.chris at gmail.com said:
>>> What is the simplest phase detecter that could work?  I think only
>>> that, and
>>> then a duouble oven crystal from eBay, a GPS and and Arduido.
>> You also need a good D2A to drive the EFC on the osc.
> A synchronous filter of a suitably level translated (CMOS analog switch
> plus low noise reference) PWM output should work well.

True.. but I think the OP was wanting something that doesn't require 
designing a circuit and building it.

So what you really want is a high performance DAC on a Arduino shield, 
or, alternately, a high performance DAC on a cheap eval board that you 
can easily hook up to an Ardino type processor.

This is a bit trickier..
Lots of ADC stuff out there, not so much DAC stuff.

seems to have a number of approaches.  Adafruit has a shield with a 
Microchip MCP4921 12 bit serial dac

here's a 16 bit solution http://www.shaduzlabs.com/article-12.html but 
it's a "build it yourself" solution.

If you're not size/mass/power constrained, you might be able to find an 
inexpensive used programmable power supply.  I do this using a Prologix 
controller driving Agilent E3646 power supplies.. Big, Expensive, etc. 
but it does work.

>>> Yes the Aruino is expensive compared to a bare uP chip but using one,
>>> I thin
>>> you could build a GPSDO without a PCB and the Arduino's USB
>>> connection could
>>> be usful for power and logging/control.
>> I wouldn't want to power a GPSDO from USB.  It will get power cycled
>> every
>> time I need to work on the logging PC.  Besides, you only get 2.5
>> watts.  The
>> oven will probably take more than that during warm-up.
> Bruce
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