<azonenberg>
RF relay most likely, that's what I use for the protection circuit
<azonenberg>
they're much more broadband and lower loss than any semiconductor based mux i've seen
<GenTooMan>
heh I always worry about relays wearing out, fortunately the part on RF relays you need worry about is usually mechanical life not contact life.
<azonenberg>
Yeah. and also these won't be cycling very often. it's not like a step attenuator you're constantly changing
<azonenberg>
the protection circuit's relay cycles once per power cycle of the instrument (it's open when powered off and closes when turned on), plus one each time you overload the input
<azonenberg>
and then this other relay will be in the single ended configuration with no power applied so it will only cycle if you hook up a diff input and then go back to single ended mode
<azonenberg>
Given that this is a rackmount instrument that is intended to be left on 24/7 sitting on a bench, i expect <1 load cycle per day on the protection relays and maybe 1-2 per day max on the SE/diff selector
<GenTooMan>
considering mechanically they are oft rated 2M cycles generally speaking it would last roughly 20 years if cycled 250 times a day.
<someone-else>
azonenberg: maintaining decent cmrr could be difficult if there are any attenuators before the diff amp
<someone-else>
if there aren't, input swing would be limited to 500mvpp or something
<someone-else>
if attenuators are on only in single-ended mode, though, this might be doable and useful for making diff probes cheaper
<azonenberg>
There are separate attenuators on each input for overload protection
<azonenberg>
The amplifier actually can handle +/- 2.5V at the input, but with my protection circuit it's able to handle +/- 5V full scale operating range and has a +/- 50V damage threshold
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<azonenberg>
I really need to move away from solvespace if they don't add chamfer/fillet tools soon
<azonenberg>
It's a nice quick easy tool for simple stuff
<azonenberg>
but very very limiting
<azonenberg>
Maybe i should give freecad another try? last time i tried it was completely useless and i couldnt even figure out how to draw a cube
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<d1b2>
<bob_twinkles> the new user experience hasn't improved but 0.19 crashes far far less than 0.18 IME
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<_whitenotifier-d>
[starshipraider] azonenberg pushed 3 commits to master [+10/-0/±2] https://git.io/JzyCT
<_whitenotifier-d>
[starshipraider] azonenberg 9d00cb1 - AKL-AD3: added a bunch of chamfers and fillets to body mechanical for better shield paint coverage
<_whitenotifier-d>
[starshipraider] azonenberg 5876ad3 - Initial sims for AKL-AD3
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<GenTooMan>
azonenberg, well my first experience with FC wasn't great however reading tutorials and the much improved plugin system make things more than tolerable. KiCADstepup also is handy for working on KiCAD related fitting issues.
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<Degi>
And it has a very easy to use mechanical FEM simulation