[time-nuts] Anybody want a Thunderbolt power supply?

Bob Camp kb8tq at n1k.org
Fri Oct 21 09:30:19 EDT 2016


Hi

At least in terms of voltage regulation (as opposed to noise), the -12V input on the TBolt is 
the *least* sensitive input on the TBolt. It’s issue is only in terms of PSRR. The internals of
the unit take care of any drift or really low frequency stuff on the -12 input.

Bob

> On Oct 21, 2016, at 9:14 AM, Nick Sayer via time-nuts <time-nuts at febo.com> wrote:
> 
> 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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