[time-nuts] Thunderbolt power requirements

[Brian Lloyd]

I am in the process of getting my "time box" finished. It has three
frequency/time references: a T-bolt, an LPRO-101, and the Chinese NTP/10MHz
server. Distribution of 10MHz and 1pps is via a TADD-1 and TADD-3
respectively. I have a Microsemi 58536A distribution amp for GPS. (I do
have one other full-time consumer of GPS and one other part-time consumer
of GPS.) I would like everything to run from a +12VDC supply to facilitate
avoiding power outages. The LPRO-101 is powered by a 12V-to-24V switcher
followed by a brute-force LC filter to clean up the PSU noise, so it is
effectively happy with anything from 9-16V.

My main +12V supply bus is a 100AH gel-cell that is being float charged at
about 13.2V but may be up to +14V during charge and down to +11V during
discharge. I want to run everything from this bus. No problem for the
Chinese NTP server, the TADD's, or the LPRO-101 with its upconverter.

The wild-card in all this is the power for the T-bolt. It needs +5, +12,
and -12. I currently am powering it from the mains using a 3-output supply.
That doesn't allow for conveniently running from battery power. Obviously
the +5 needs to be pretty tightly regulated but not sure about the +12 and
-12. Can I cheat and run the +12 from my 12V power bus or does it need to
be more tightly regulated?  If necessary, I can boost to +15 and then
regulate down to +12.

I suspect the primary use for +12V is the oven. If the oven controller is
analog using something like a FET or BJT as the control element for the
heater, supply voltage should be pretty much a non-issue as these devices
have a constant current for a given base/gate drive, thus pretty well
decoupling the heater current from the supply voltage.

Of course I can derive -12V using an isolated switching module. Anyone know
the -12V current requirement of the T-bolt off their heads? (Yes, I know, I
can take everything apart and stick an ammeter in series with each leg but
if someone knows, I can avoid having to do that. Yes, I am being lazy.)

Thanks in advance.

-- 



Brian Lloyd
706 Flightline
Spring Branch, TX 78070
brian at lloyd.aero
+1.210.802-8FLY (1.210.802-8359)