[time-nuts] Chinese NTP Time server

[Brian Lloyd]

On Mon, Dec 23, 2019 at 9:42 AM Brian Lloyd <brian at lloyd.aero> wrote:

>
>
> On 12/22/19 17:16, Adrian Godwin wrote:
> > Voltage converter might be one of these  :
> >
> > https://www.we-online.com/catalog/datasheet/177920521.pdf
> >
> > You can also sometimes find a similar device on an old 10baseT ethernet
> > card, where it generates a -9V supply.
> That is definitely on the right track. I need 7.5V out (if it tracked
> the input that would be perfect) and the pinout is different, i.e. the
> NTP server has a pinout of gnd, in, out, gnd, respectively.
>
> But you definitely found something in the ballpark. Thanks!
>

Ha! Found it! It is the Traco TBA1-1219, isolated DC/DC converter. The
floating output can have the + side connected to ground to make a negative
supply. Turns out the input is just the raw 12VDC input and -9V output
should be more than enough for the 79L05 to regulate down to -5V for the
negative rail on the op-amp.

I couldn't find it earlier because I was looking under 'inverting
regulator' instead of 'isolated DC/DC converter'. You put me on the right
track.

Parts ordered from Mouser. I went with the LT1227 op-amp for the buffer.
I'll post how it works when I get it all together.

-- 



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