> On Aug 30, 2016, at 9:26 PM, Mark Sims <hol...@hotmail.com> wrote: > > The -12V is used to drive the RS-232 signals... it also eventually gets to > the EFC dac so it can swing below ground. Also, the +12V gets to the DAC. > Pay close attention to generating noise on these lines.
I’ve designed a prototype. I’ll provide noise and ripple measurements when I get the first boards back. I’m going to shoot for <= 35 mV P-P. If you need better than that, then it probably turns into a hybrid switching+linear system, which would be more expensive. It’s been a while since I looked, but I believe that’s what I was able to achieve with the supplies for the FE-5680A GPS discipline board. > > Also, when I did Lady Heather's temperature control PID (with great help from > Warren Sarkison) I did some measurements on the effects of temperature on > the system with only the tbolt under temperature control and also with both > the power supply (the brick supplied with the original TAPR orders) and the > tbolt temperature stabilized. It seems about 1/4 to 1/3 of the temperature > sensitivity of the system could be attributed to the power supply and the > rest came from the oscillator/tbolt. Some attention to the tempco of the > power supply would be a good thing. I’ve not made any efforts along those lines to start with. For one, the input is +12 V and is simply passed through as the +12 volt output (there is a TVS and cap on the input, however). Given that the Thunderbolt that I have on loan came with what I can only guess was once a laptop power supply, I started off thinking the bar was pretty low. If you want the hybrid approach, then adding the temperature compensation to the linear regulators would clearly be the way to go. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
