[time-nuts] Helium and MEMS oscillators don;t mix well

jimlux jimlux at earthlink.net
Thu Nov 1 12:22:54 EDT 2018


On 11/1/18 8:52 AM, Poul-Henning Kamp wrote:
> --------
> In message <B084B24B-DD81-48A2-87AE-D43D74133C59 at n1k.org>, Bob kb8tq writes:
> 
>> A lot of Radon and *really* poor ventilation….
> 
> Yup.
> 
> But a LOT of Radon is not without interesting "side-effects", such as
> much easier ionization due to the alpha radiation.
> 
> To get to relevant He levels via the Radon route, we are talking
> deep unventilated mineshaft kind of concentrations...
> 
> Hydrogen is a lot more plausible in my view.
> 
> 

Yeah, but in concentrations typical in the "room", I doubt you'd see the 
effect.  The experimenters put the phone in a bag full of helium and it 
took hours.  I would expect the same in hydrogen.

That's a lot different than a <1% concentration. I assure you, that if 
there was a helium leak/vent/boil off that made the room concentration 
1%, the room oxygen sensor would be alarming (having dropped to 20%) and 
people would be running for the doors.

I'd be betting more on some RFI/EMI issue from the RF fields or the 
magnetic fields, both of which are quite strong in an MRI facility.



However, in true time-nuts fashion, I'm going to rummage around for some 
older SiTime oscillators on an eval board at work, and we can do a 
*real* test.

I got some samples from them a few years ago, so all I have to do is 
find that tiny plastic bag with the tiny 2x2mm parts in it.

Then I have to find some spare hydrogen and helium..

After all, we really need to evaluate it in an atmosphere of Argon and 
CO2,  (Mars gas) - I'll see if we've got some around - we were doing RF 
breakdown tests in simulated Martian atmosphere <grin>  (BTW, the 
Martian atmosphere is unique in that it probably has the lowest "minimum 
sparking voltage" in the universe)









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