[time-nuts] NTBW50AA Power supply

Paul Berger phb.hfx at gmail.com
Tue Sep 3 11:17:09 EDT 2013


I have a Nortel /Trimble 45000 which appears to be the bare board that 
is is in the NTBW50AA and I have been running it for several months now 
off of the power cube for an old printer that is rated for 30VDC, it is 
just rectified and filtered, the output from the cube is not 
regulated.    The input power does feed a switching regulator on the 
board that generates the voltages that the GPSDO requires.

The manual does say that it may shut down at +31V which may suggest 
there is some voltage sensing but I don't recall seeing anything like 
that when I examined the board.

Paul.
On 9/03/13 10:46 AM, quartz55 wrote:
> Well, reading the spec sheet, it says -48VDC (-40Vdc min, -60Vdc max) at 2.8A for warm up and .6 during run time <350mv ripple, OR +24Vdc (20Vdc min, 30Vdc max) at 3.57A for warm up and 1.03A run <240mv p-p ripple.  I'm assuming that after the bridge there's some sort of switcher that feeds the unit +5,+12, -12, which I understand is typical for the Thunderbolt units.  But I don't have this thing in hand yet.  It very well may work off +-12V which is essentially 24V, but I doubt if it will work if the voltage is too low, but I'm just speculating.  I know it won't work of 0V which is between 12 and -48.  It may be a variation on one of those 90-220VAC input switchers that's made to work off DC.  It may just be the way they had to write the specs, but will work with about anything.
>
> I'm not trying to be picky here, I don't want to mess up right off the bat.  Looks like I may be able to use this 5A transformer that puts 35V out of a bridge circuit into an 8200uF cap, but I need to measure the ripple at 1A or so.  I can always add a lot more uF.
>
> Thanks for those links to the supplies though.
>
> Yeah, I see where the digital ground is used for the supply return, not the case so the PS should be isolated pretty well.
>
> Is anyone using one of these particular units?
>
> Dave
> N3DT
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