[time-nuts] Looking for a low power very low noise DC/DC converter (100 - 200 ma 10VDC or 15VDC)
kb8tq at n1k.org
Mon Oct 31 15:42:39 EDT 2016
…. or you could do a milled box inside a milled box inside a milled box. Isolate each one from the others. Filter all leads at each “goes in” and each “goes out”. Put the input side in it’s own cavity in each box. Put the output side in it’s own cavity. Put the control signals in their own separate sealed section. Fasten each section on each box down with it’s own lid and it’s own EMI gasket. Three boxes 4 sections per box (you still need the “guts” somewhere. It’s still not totally clean, but it will be pretty good.
> On Oct 31, 2016, at 1:50 PM, ed breya <eb at telight.com> wrote:
> Yes, for best quietness, you definitely should "can it up" in a metal box, and use feed-through caps for all the I/O, including the commons or grounds. You have to figure out also where all the currents flow, and contain the loops. With sufficient L-C filtering on the input and output (all inside the can along with the converter), you should be able to get whatever degree of cleanliness is required. The in and out ports should include common-mode filters (also inside the can). When it's all said and done, there should be the input power port +/- via feed-throughs, and the output +/- supply port via feed-throughs.
> The can should not carry any current except that which flows through the common-mode filtering, so don't connect it internally to the either input or output "common," even though ultimately they are tied externally. This will help to keep the ripple and displacement current loops contained within the can. The can should be solidly connected (mounted) on the system ground chassis, and the feed-through caps will give the final degree of RF suppression. The I/O ports then can be connected as required.
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