[time-nuts] WWVB teensy BPSK early experiments

[jimlux]

On 10/31/20 5:42 PM, paul swed wrote:
> Jim
> Thanks for the details. I took a serious look at popping the xtal out and
> am afraid its a bit beyond me since there are 4 pads that need to be
> heated. I have worked on very small stuff under the microscope. But this
> seems problematic. I sort of thought all the bits would get upset. No free
> lunch.

It's only hard if you want to save the crystal for later use <grin>.
Soldering iron right on the top of the crystal package, all 4 pads get 
soft, scrape it off with the xacto knife.

Then, solder on the tiny wires from a coax pigtail. Blob of superglue to 
keep it from breaking off.

I had about 50 of them, so if I broke it, I had more to try, but it 
worked ok.

But, as noted, not particularly useful.






> No matter not popping the xtal. Mainly because if anyone else did want to
> build the magical solution it would be as bad as soldering lots of chips.
> Super fine wires to very small pads.
> But at least at the moment perhaps thats not critical to developing
> something.
> I did tinker with delay and will need to use a scope at this point to see
> the effects.
> Regards
> Paul.
> 
> 
> On Sat, Oct 31, 2020 at 7:35 PM jimlux <jimlux at earthlink.net> wrote:
> 
>> On 10/31/20 11:42 AM, Bob kb8tq wrote:
>>> Hi
>>>
>>> …..errr…..
>>>
>>> Can you pull the clock oscillator off the Teensy board? (Yes, the
>> soldering
>>> iron would be involved).
>>>
>>> Will the clock input to the MCU accept something like 10 MHz? If so
>> solder
>>> on a cable ….
>>>
>>> At that point whatever the Teeny does is locked to the 10 MHz. If that
>> comes
>>> from one of the $3 eBay OCXO’s, steer that with a DAC output … now you
>>> have a WWVB GPSDO.
>>>
>>> Indeed, if the Teensy needs 28 MHz, then the OCXO will not be quite as
>> cheap.
>>>
>>> Bob
>>>
>>
>> I've tried this - It will run just fine, but *all the UART and USB
>> speeds change*.  So, basically, the USB stops working, and you need to
>> set your serial port to something like 112.8 * 10/28 (and it takes a bit
>> of fiddling to get it to work right)..  I sort of cheated, and switched
>> back and forth - signal generator to 28MHz, load and debug software,
>> start it, then switch generator to 10 MHz.
>>
>> And of course, all the functions that are time based, like delay() are
>> the wrong length.
>>
>> One could probably figure out a relatively few patches to the
>> Teensyduino code base that would fix all this (clock rate is a variable
>> - you can run the teensy at multiple clock rates, even with the same
>> crystal)
>>
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