[time-nuts] 4046 variations (was EPE GPS....)
magnus at rubidium.dyndns.org
Sun Sep 27 22:38:12 UTC 2009
Lux, Jim (337C) wrote:
> Design AND component...
> Easy to claim heritage if all you do is change a resistor or a capacitor.
> Tougher to claim if you change the active components, particularly if it's
> functionally different (e.g. Substituting a 2n3904 for a 2n2222 isn't a huge
> deal.. Changing a NPN to a PNP and reversing bias, or using FETs instead of
> bipolars.. That would be a big deal)
> Keeping those 30 year old databooks is important.. (as we tell the folks who
> say: "why do you need all that shelf space.. Surely those datasheets are
> available on line").. 1980s design, modified in 1990s, using parts first
> available in 1970s, launched in 2000s, gets to Saturn in 2010s, has inflight
> Oddly, the 4000 series CMOS are still heavily used. Back in the 70s and
> 80s, I hated those parts because they were ESD sensitive (compared to
> straight or LS ttl), but by today's standards, they're rock solid, have huge
> junctions, work at any supply voltage.
I have been a fan of keeping old databooks. Keeps collecting them.
For instance, in practice my most used databook is the RCA CMOS databook
from 1982. Contains some very useful insights into the 4046 design which
the online datasheet does not reveal.
I don't have all the things I would wish I had, lacking alot of analog
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