azonenberg changed the topic of #homecmos to: Homebrew CMOS and MEMS foundry design | Wiki: http://homecmos.drawersteak.com/wiki/Main_Page | Repository: http://code.google.com/p/homecmos/ | Logs: http://en.qi-hardware.com/homecmos-logs/
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<SpeedEvil> In principle - is there any benefit to a MOSFET with substrate brought out?
<davidc__> SpeedEvil: yes, no body diode
<davidc__> Well, I mean, there is still a diode effect
<davidc__> but you can choose your bias so its not a problem
<whitequark> oh. that is why these are used
<whitequark> cool
<SpeedEvil> I guess there are a whole heap more substrate -related voltage limits?
<SpeedEvil> http://www.digikey.com/product-detail/en/EPC2007/917-1015-2-ND/2351748 - a whole family of bare die power GaN FETs stupidly fast.
<whitequark> neat
<SpeedEvil> Ridiculously low Qg
<_Sync_> SpeedEvil: they were popular
<_Sync_> where you needed perfect diodes
<_Sync_> but you can get integrated parts that do the same now
<SpeedEvil> yeah - 'ideal diodes' are nice.
<_Sync_> but well, they are pretty obsolete now
<whitequark> _Sync_: hm ion pump?
<whitequark> what for
<whitequark> rated at 50W so might be overkill
<_Sync_> whitequark, no real use, I just picked it off ebay for 3 bux + shipping
<_Sync_> so why not
<whitequark> wow that is cheap
<whitequark> envy
<whitequark> was it marked as an ion pump or just as unknown gizmo?
<_Sync_> it said varian starcell
<_Sync_> but it ran out like thursday morning
<_Sync_> btw, the trick to get glass milled crack free is to glue it onto something
<_Sync_> or wax it
<SpeedEvil> LASERS
<SpeedEvil> The real trick to doing it crack free is to heat to 650C first
<SpeedEvil> And yes - waxing onto stuff is awesome.
* SpeedEvil is making a tiny rapid glass-melting kiln.
<whitequark> _Sync_: these routinely go for $1000
<whitequark> such luck
<_Sync_> it's just a small 50l pump
<_Sync_> I could also just take one home from work
<whitequark> ...
<whitequark> where do you work
<_Sync_> university institute
<whitequark> ah
<_Sync_> they are not magic
<_Sync_> even though some people think they are
<whitequark> they aren't magic, they're just expensive like the rest of vacuum tech
<_Sync_> yeah, it's the way it is
* SpeedEvil has an awesome two-stage oil pump he picked up from a scrapyard.
<SpeedEvil> Edwards thingy
<SpeedEvil> ~0.1 micron
<_Sync_> I got a few boilboilers
<SpeedEvil> I need to add a sublimation pump in front of it
<_Sync_> but I have swapped all pumps actually doing stuff to dry scrolls
<_Sync_> why add a TSP in front? that's not really effective
<_Sync_> with a turbo infront of the rotary that'd make sense
<_Sync_> to get the light gas rate up
<_Sync_> but otherwise, eh
<_Sync_> they also just get their advertised pump rates when you cool them with LN2
<SpeedEvil> That is because I can't make a turbopump
<_Sync_> just buy one
<_Sync_> you won't get any benefit with the TSP
<_Sync_> the pressure your rotary achieves is too high for it to be useful
<whitequark> I got an almost working turbo for $250 or so
<whitequark> ext250h. leaking a bit but fine otherwise
<_Sync_> I'd just buy working ones
<_Sync_> they come so cheap
<whitequark> well I thought it was working
<davidc__> _Sync_: from where?
<whitequark> got another working in RU with controller for $400 or so
<_Sync_> ebay davidc__
<_Sync_> lots of them go for around 150 bux if you wait a while
<SpeedEvil> They almost don't come up on UK ebay
<_Sync_> then just buy from germany
<SpeedEvil> And - well - shipping...
<_Sync_> gotta watch out tho
<_Sync_> either pfeiffer or leybold
<_Sync_> pfeiffer is a 2 phase motor with hall
<_Sync_> and leybold is 3 phase
<davidc__> there's a really cheap untested pffeifer on ebay for $150, with cheap shipping
<davidc__> I might grab it and see if I can build a controller
<davidc__> shouldn't be too hard.
<_Sync_> there is a design on fusor.net
<whitequark> I looked into an edwards controller
<whitequark> your bog-standard BLDC controller
<whitequark> on some common TI IC
<_Sync_> yeah, edwards also sometimes is just a 3 phase one
<_Sync_> the annoying thing is the magnet bearing control on big pumps
<_Sync_> on some it is simply current fed
<_Sync_> but some do some more magic
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<_Sync_> but basically rotary and turbo is the best way to get started
<whitequark> yup
<_Sync_> I got annoyed by the oil vapors in my lab
<_Sync_> so I just swapped to edwards xds10
<_Sync_> because f diff pumps