[time-nuts] Anybody want a Thunderbolt power supply?
nsayer at kfu.com
Fri Oct 21 09:14:03 EDT 2016
Well, because it's easily an order of magnitude more expensive than a 7912. $5 instead of 50¢ (Q:1).
If it *matters*, then fine, but I am sensitive to cost efficiency in addition to efficacy.
If you put the board in a box in a stable temperature environment (which I'd kind of assume you'd do if you cared about temperature stability generally), then how far do you really have to go?
Sent from my iPhone
> On Oct 21, 2016, at 1:59 AM, Attila Kinali <attila at kinali.ch> wrote:
> On Fri, 21 Oct 2016 00:20:43 -0400
> Scott Stobbe <scott.j.stobbe at gmail.com> wrote:
>> The bad side of a 7912 is in long-term stability and tempCo, the sample I
>> tested had at least a 150 ppm/degC tempCo, which is going to put a serious
>> lump/bump in the 10s tau to gps crossover point on an allan deviation plot.
> If the Thunderbolt ist most sensitive to the -12V input, why not use
> something like the LT3090? Its temperature coefficient is quite low
> in the order of a few ppm/°C around room temperature. Using a metal
> film resistor that should keep the output variations low as well.
> As added bonus, you get a very low output noise.
> And while you are at it, use three LT3090 for the positive supplies :-)
> Attila Kinali
> Malek's Law:
> Any simple idea will be worded in the most complicated way.
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