Hi > On Oct 31, 2014, at 7:11 AM, Simon Marsh <[email protected]> wrote: > > Many thanks to everyone for your suggestions and patience. > > Short answer, the problem was power related, but more accurately, it was a > shielding problem. > > Long answer, it was not immediately obvious as power in the setup itself > didn't seem to be a problem. I need 12v (for the mv89a or 8663 OCXO), 5v (for > the MicroCrystal OCXO and to feed the BBB) and 3.3 for logic. Each section > has its own LDO with a sprinkling of bypass capacitors and these are fed from > a single power supply in a star. I'd already tried different power supplies > and monitoring the LDO outputs for noise. > > After pretty much swapping everything out yesterday and not seeing any real > change to the problem, it was becoming clear that I needed to look a bit > wider. The hint that ~60khz related to switching power led to tracking down a > nearby DC step-down converter as the cause. > > No doubt there are lots of thoughts of 'well, that shouldn't be a surprise > working on a shoddy breadboard’,
No, not at all. Only that this part of the project is always were most of the work goes. To *not* talk about that makes people less likely to carry this sort of thing to a working finish. Bob > but note that I only did this to narrow down what was causing the problem > after initially seeing it with the proto cape. The cape setup should have > been more robust, so I need to look at this closer to see where I'm lacking > appropriate shielding. > > I'm happy to have found the problem, and all the analysis yesterday has given > me lots of data about the impact of different components and stability of the > edge transition, so it's all good stuff :) > > Cheers > > > Simon > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
