Brings to mind two interesting numbers:
I figured out when I was ten that it takes about 2 weeks to count to a million
at one number/sec.
Much later in graduate school I learned from an astronomer that a year has pi x
10^7 seconds.
Andy Backus
From: time-nuts
On 2/10/19 4:36 PM, Tom Van Baak wrote:
Christopher Shawn McGahey's wrote his phd at Georgia Tech on the subject,
and it sorts a lot of facts from fiction.
"HARNESSING NATURE'S TIMEKEEPER: A HISTORY OF THE PIEZOELECTRIC QUARTZ CRYSTAL
TECHNOLOGICAL COMMUNITY (1880-1959)"
Back in the late 70's I worked for a mini-computer company. They were a
horrendous paper-work factory... spec after needless/useless/virtually
identical documentation requirements. I wrote one document where I put all
the timings in units of "ffn"... femto-fortnights. It was over three
Mica is a sheet silicate mineral little or no carbon present.
Bruce
> On 11 February 2019 at 11:15 Bob Bownes wrote:
>
>
> >
> > 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.
Luca wrote:
> There is a little strangeness: the wave clipper darlington transistor Q1 is
> marked as 1854-0611, equivalent to the standard darlington 2N6055. But why
> there is a simple 2N3055 in the picture? Some sort of version update fail?
One other reader (Ian) pointed out this same
> Christopher Shawn McGahey's wrote his phd at Georgia Tech on the subject,
> and it sorts a lot of facts from fiction.
"HARNESSING NATURE'S TIMEKEEPER: A HISTORY OF THE PIEZOELECTRIC QUARTZ CRYSTAL
TECHNOLOGICAL COMMUNITY (1880-1959)"
>
> 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.
Beware inclusions that will make the surface rough and change the behavior,
particularly breakdown voltages.
> The reconstituted
> 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
>
> There's a lithium battery holder - but suspect that is just for the local
> RTC rather than backing up SRAM which might hold the passwords.
There is usually a small SRAM in the RTC chip - just for things like this.
> I tried removing and replacing the battery anyway to no avail
If you
Hi Jason
Thank you for the suggestions. Yes, I interrupted the boot process but
there is no prompt when I do that, I basically get a prompt/text saying
something like "press any key to abort the boot process" and when I do
there is no further communications. I can try entering
> Thank you for everyone's suggestions. I'm definitely connected to the
> correct serial port for configuration and communication using com port
> settings 9600,n,8,1. When power is applied I get various boot messages
> before being presented with a ">" prompt whereupon I can enter "help"
>
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.
Thank you for everyone's suggestions. I'm definitely connected to the
correct serial port for configuration and communication using com port
settings 9600,n,8,1. When power is applied I get various boot messages
before being presented with a ">" prompt whereupon I can enter "help"
and get
In reading back over my sarcastic description of the 5061A battery charger, I
was pretty hard on the unnamed designer of that circuit. I did find a
schematic of an older generation batter charger for the 5061A, and it had the
same basic implementation.
As far as I know, the circuit, in all
Hi Poul -
I'm only familiar with the system design for the 5061A/B, and can't really
speak to a general HP T design approach. Maybe Rick has some insights.
My real expertise is HP Inkjet printers, but those stories are for another
mailing list.
Reaching back to the 5060A, I think Lou
The 5061A/B is the only HP T product that I worked on deeply, and yes, the
manual is very complete and accurate, save a typo here or there.One careful
reader (Ian) pointed out a typo in the generic 2N part number for the main TO-3
power transistor!
The product family was old enough that
Thanks Hugh for the story, and thanks for the schematic!
Quite interesting.
There is a little strangeness: the wave clipper darlington transistor Q1 is
marked as 1854-0611, equivalent to the standard darlington 2N6055. But why
there is a simple 2N3055 in the picture? Some sort of version update
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