[time-nuts] 5370 processor boards available

cheater00 . cheater00 at gmail.com
Thu Feb 27 08:57:34 EST 2014

If having a battery in the device makes some of you queasy, you could
always put it outside, on the back. But I seriously believe there are ways
to make battery backup which will not leak.

On 27 Feb 2014 06:52, "Chuck Harris" <cfharris at erols.com> wrote:

> That fix presumes that the power line never quits at
> inappropriate times.  This winter has provided me with
> ample reminders that power can go out anytime.
> I think a better solution would be to find a very large
> "super cap" and power the BBB from that while giving it
> a power fail interrupt to quickly sync the file system.
> -Chuck Harris
> John Seamons wrote:
>> On Feb 25, 2014, at 12:59 PM, John Seamons <jks at jks.com> wrote:
>>  I may have a solution for the power-off problem that doesn't involve
>>> batteries
>>> or supercaps. It has the added advantage of providing instant-on.
>>  From the latest documentation:
>> "One solution to the annoyance of having to halt the BBB before the
>> instrument is
>> powered off is simply to keep the BBB running by providing it a secondary
>> source
>> of power via the USB-mini port. The BBB already understands how to select
>> between
>> two sources of power: the USB-mini and +5V barrel connectors (the latter
>> of which
>> is actually being delivered from the 5370 via the board expansion
>> connectors). The
>> app detects when the instrument has powered down and resumes running when
>> power is
>> restored. USB power could come from an external USB hub or charger. You
>> may have
>> to obtain a longer USB cable than the one supplied. Be certain to only
>> use the
>> USB-mini connector that is adjacent to the Ethernet RJ45 connector. Do
>> not use the
>> USB-A connector on the other end of the board as that port will not
>> accept input
>> power.
>> Some of you might even figure out how to derive +5V for the USB-mini
>> cable from
>> the 5370 oven power supply card that is always powered if the instrument
>> is off
>> but the line cord is plugged in. But beware of the potential problem of
>> conducting
>> noise from the BBB to the reference oscillator over such a connection.
>> Some
>> experimentation and measurement is necessary. The planned USB/Ethernet
>> connector
>> card that replaces the current HPIB one at the back-panel could host a
>> voltage
>> regulator. Aligator clip connections to the '+25V UNREG' and GND test
>> points on
>> the oven power supply would alleviate the need for any soldering."
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