[time-nuts] HP Stories: Battery Chargers, and a fading idolization of HP

[jimlux]

On 2/10/19 10:16 AM, Richard (Rick) Karlquist wrote:
> On 2/10/2019 4:35 AM, Rice, Hugh (IPH Writing Systems) wrote:
> 
>>
>> Somewhere over the years I picked up this line:   “A good engineer is 
>> a lazy engineer.  They are always looking for the easiest way to do 
>> things.”     The designer of the 5061A battery charger was definitely 
>> not a lazy engineer.
>>

My contention is that ALL engineers are lazy to a certain extent - 
rather than everyone wading across the river and getting wet, you build 
a bridge - rather than dig in the soil of a field with a pointed stick, 
you get an animal to drag it across the field for you - etc.

The idea of "do something with less work" or "do something that cannot 
be done" is sort of fundamental to engineering.




> 
> 2.  The giant unobtainable mica capacitor has Len's fingerprints
> all over it.  On the 5071, Len wanted to use a tantalum capacitor
> for the power supply filter.  Imagine what that cap would now cost
> in these days of "conflict minerals".  The project team mutinied and Len
> backed down.  It was all moot anyway after we decided to use Vicor
> modules.  That seemed very avante garde at the time, but now seems
> sensible.  BTW, I heard the those giant WWII military mica capacitors
> were made from large contiguous chunks of mica.  A some point after
> the war, the mica mines were played out, similar to the quartz mines,
> and only small pieces of mica were available.  The capacitor vendors
> made "reconstituted" mica out of crumbs.  The crystal vendors didn't
> have that option so they had to invent synthetic quartz.

Yes, those brown roughly 1" square caps used intact sheets of mica as 
dielectric. You can easily split the mineral into uniform, thin, 
transparent sheets.

The reconstituted caps are still around - used in high power RF circuits 
(mica has really low loss, but high epsilon) and in Tesla coils (a sort 
of special case high power RF). Most of them are surplus Russian/Soviet.