søndag den 30. december 2018 kl. 04.53.15 UTC+1 skrev George Herold:
On Saturday, December 29, 2018 at 7:49:13 PM UTC-5, Phil Hobbs wrote:
On 12/28/18 11:49 AM, George Herold wrote:
On Friday, December 28, 2018 at 10:14:41 AM UTC-5, Phil Hobbs wrote:
On 12/28/18 9:51 AM, 698839253X6D445TD_at_nospam.org wrote:
Not really. The patent talks about photocurrent, for one thing,
and for another, using the same type of ambient light sensing
photodiode for both the ambient and display brightness is a
nice intuitive idea that also makes physical sense.
Besides, a 2.5 mm square PD is easy to mount right next to the
ambient light sensor for the ambient reading (ensuring good
tracking) and easy to tape upside-down on top of a
full-brightness area on the display to measure its brightness
in a repeatable way.
Photometer heads are bigger and clunkier, so that would be hard
No idea what it is all about, but if you want to track display
brigtness versus background brightness, and that is likely into
the direction you look, then simpe video camera, processing, mask
out background, mask out bright spot (brightesr spot perhasp) in
display, compare if it tracks or not. | () || | cam
display | | background tronix
As I've said for thirty years, "A software guy thinks that the way
to do any optical thing is to point a camera at it and crunch the
daylights out of the resulting crappy data."
You can make nice linear measurements with the right camera, but
ordinary video cameras have so much auto aperture, auto
integration time, gamma correction, colour gamut optimization,
yadda yadda, that linear measurements don't happen by accident.
Photodiodes for me all the way.
Hi Phil. (I trust everyone had a merry Christmas) DMM in current
mode and a photodiode is my fav poor mans light meter, very simple.
I've got an older fluke 87 in the lab. I thought it had a 10 uA
scale and minimum resolution of 1 nA... but I'm not in the lab this
week and may be mistaken.
My 1988-vintage Fluke 87 is on the sick list at the moment.
Huh, what's wrong? Mine had a flaky input and a ~$20 new connector
I bought it for a bit of moonlighting while I was a postdoc at IBM
Watson--I had a small gig involving a gizmo to fuse medical waste into
compact blocks to prevent it from washing up on East Coast beaches after
being dumped by mob-controlled 'waste disposal' outfits. The situation
didn't last long, so the opportunity didn't either. Interesting problem
We've also go a new keysight DMM... but again that will have to wait
till next week for me to check. Is there any time crunch?
Nah, I got another Keithley 177 for $46 including shipping. It has 1 nA
resolution, which is fine for this job. Thanks though.
George H. (ps unrelated, we got our first robot (Roomba 690) for
xmas.. fun... though it can spend a lot of time underneath the couch
trying to find a way out.) (Or maybe it is doing something else under
Fun. We got one of those some time back for a friend with limited
mobility. It was fun to watch for awhile but was not reliable enough
for that sort of situation.
I just want it to try and keep the pet hair under control, so far it
does that, but needs to be cleaned before each run.