EDAboard.com | EDAboard.de | EDAboard.co.uk | WTWH Media

DMMs with decent current resolution?

Ask a question - edaboard.com

elektroda.net NewsGroups Forum Index - Electronics Design - DMMs with decent current resolution?

Goto page Previous  1, 2, 3

Lasse Langwadt Christense
Guest

Sun Dec 30, 2018 2:45 pm   



søndag den 30. december 2018 kl. 04.53.15 UTC+1 skrev George Herold:
Quote:
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:
pcdhobbs 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
to do.

Cheers

Phil Hobbs

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.

Cheers

Phil Hobbs
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. Sad
Huh, what's wrong? Mine had a flaky input and a ~$20 new connector
fixed it.

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
though.


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
there :^)

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.


it can be worse, https://youtu.be/ijdZ6qgprkM

Phil Hobbs
Guest

Sun Dec 30, 2018 8:45 pm   



On 12/29/18 10:53 PM, George Herold wrote:
Quote:
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:
pcdhobbs 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
to do.

Cheers

Phil Hobbs

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.

Cheers

Phil Hobbs
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. Sad
Huh, what's wrong? Mine had a flaky input and a ~$20 new connector
fixed it.


Dunno yet. It's had a flaky switch for some time. I'll try contact
cleaner and see.

Contact cleaner brought back one of my HP 3325As--the relays are made of
switch contacts touching the hard gold plating on the board.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

Goto page Previous  1, 2, 3

elektroda.net NewsGroups Forum Index - Electronics Design - DMMs with decent current resolution?

Ask a question - edaboard.com

Arabic version Bulgarian version Catalan version Czech version Danish version German version Greek version English version Spanish version Finnish version French version Hindi version Croatian version Indonesian version Italian version Hebrew version Japanese version Korean version Lithuanian version Latvian version Dutch version Norwegian version Polish version Portuguese version Romanian version Russian version Slovak version Slovenian version Serbian version Swedish version Tagalog version Ukrainian version Vietnamese version Chinese version Turkish version
EDAboard.com map