[time-nuts] Thunderbolt Controllers

Bruce Raymond bruceraymond at ameritech.net
Mon Jul 7 11:07:57 EDT 2008

Hi Neville,

As a thought, you might want to look at a Basic Stamp from Parallax. 
These are PIC chips (at least they used to be) coupled with an EEPROM 
and are programmed in BASIC. Here's a site for some additional data -


Bruce Raymond

Neville Michie wrote:
> My pendulum produces pulses at a rate of one per second.
> That signal clocks a latch that samples the less significant bits of  
> my reference oscillator  (100kHz or 1MHz)
> in a counter.
> The latched values drive a 12 bit D-A converter (a R - 2R chain).
> So I have a phase signal updated every second, and which resolves 10  
> or 100 microseconds.
> The data logger samples this every 10 seconds or so and so logs a  
> graph of drifting phase.
> The data from the logger can then be used in a spread sheet to  
> analyse periodicity
> of fluctuations and correlation to barometric pressure and temperature.
> When barometric pressure and temperature are successfully eliminated  
> by compensating
> the pendulum, I hope to only have planetary resonances, gravity tides
> and noise disturbing my clock.
> Currently I have a 1MHz OCXO driving the system, but it drifts  
> significantly.
> This is a home brew oven, running at about 40*C, consuming about  
> 250mW, quite easy to
> back up with a 12V battery.
> The HOBO data logger has 4 inputs of 0 - 2.5 volts and 12 bit  
> resolution, and it runs
> for 4 years on a lithium cell.
> It takes a lot more power to run a computer, and then you have to  
> reboot after each power
> interruption, and so I have not found it worth while to get a machine  
> just for the project.
> But the overall check of the system is to compare clock time with UTS  
> once in a while
> to cover the chance of slipped seconds. At the present time I use WWV  
> when I can find it,
> but what I would really like is a clock showing UTS in a form that  
> can be compared to a clock.
> That means one second audible pips and a marker on the minute. Just  
> seeing numbers
> rolling over on a computer is not good enough to check the timing of  
> the second hand of
> the clock. You need ear - eye coordinated signals. With WWV I can  
> compare to 1/20th of a second.
> Although I have programmed systems in a variety of languages in my  
> working life, the only
> languages that have stuck are Fortran and Basic. All the rest are  
> forgotten after a year or two.
> I do not wish to start again to learn a new system just for one task,  
> and it is obvious that there
> are so many micros abroad and none of them is going to be universally  
> useful for future tasks.
> cheers, Neville Michie

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