What LED digits color You like? <poll inside>

[james_s]

Generally the poisoned cathodes will recover with use, sputtering normally refers to cathode material being vaporized and depositing on the glass or other internal structures. VFDs have multiple mechanisms responsible for the fading. One is phosphor aging which is directly related to how hard it is driven, the other is cathode emission dropping, which can often be recovered at least for a while by overdriving the filaments for a few seconds. It's true that both display techs have finite lifespans although LED displays don't last forever either.

One thing I forgot to mention earlier is white LED displays. They look cool when new but they deteriorate faster than any other display type I can think of other than possibly OLED. Some of the products we made at a previous place I worked had white 7-segment displays for the clock on the front panel and within a year the more used segments/digits had become considerably dimmer and grayish looking. They looked like crap.

[Gyro]

I normally reduce the operating current of my panaplex display equipped gear when I get it - they are normally a bit too bright for a small domestic lab anyway. Luckily, the standard DS8881 drivers have a programming pin for this. Yes, I've successfully recovered poisoned incompletely lit segments on standard Sperry / Beckman displays with a bit more drive to clean the surface. Luckily the stuff I have uses standard pinout 1 1/2 to 3 digit displays. I know the custom Datron 106x/7x display can cause problems and because they're multiplexed, it can be difficult to revive them.

I've only ever seen one Beckman display that was visibly sputtered (cathode material deposit on glass) but that still worked fine, with no apparent loss in brightness.


It's sad to see a failing VFD, they can be filtered to a rather sickly yellow but you loose a lot of light output. One tip I got from a Noritake rep several years ago is to avoid phospors other than green. Red apparently poisons the display (not sure if it is cathode or phosphor poisoning), that's why you typically only see a single tiny red record icon etc. on VCR displays.

[GeorgeOfTheJungle]

The Victor desktop calculators of the 70's had those displays too.

[Bud]

Blue is actually a very difficult colour for us to see

Not sure if that is the case. In Toronto the public transit buses have two blue lights placed just below the roof line at the front of the cabin. They are blue, not whity washed ones. When you are waiting for a bus and look up the street you can see lights from the approaching bus in traffic at quite a distance, even at day time, so you see that a bus is coming.

[Fungus]

Blue is actually a very difficult colour for us to see

Not sure if that is the case.

I have no problem seeing the sky, or anything else that's blue. 

(the sky is usually blue where I live, YMMV)

[xrunner]

White is the best choice - that's why it's winning in the poll. 

[Fungus]

White is the best choice - that's why it's winning in the poll. 

Is that because there's no "orange" option? 

Maybe if we add red+yellow together it'll beat white.

[GeorgeOfTheJungle]

Blue is ugly, and a sure sign of chinesium inside :-)

[Fungus]

Blue is ugly, and a sure sign of chinesium inside :-)

Yeah, no western designer ever specified blue LEDs for anything. Right?

[tautech]

White is the best choice - that's why it's winning in the poll. 

I started that ! 

Others have devious minds too. 

[floobydust]

I'm surprised LED display manufacturers are not offering anything different.

First place is blue-green, it's a blue LED with VFD-coloured phosphor. Rarely seen, I think it's a custom part. Kingbright offers pastel colours for discrete LED's, we should talk them into making "ice blue" 7, 14-seg displays.

Second place is white, with a tinted display window/bezel to get many colours.

[lowimpedance]

Yep, Orange (the colours are a lot closer than they look in the photo). Orange LEDs look very nice too though.

Those aren't LED though, they're Sperry neon 7-segment displays. Unique and very attractive displays, but the lifespan is finite and replacements are virtually impossible to find.

Their finite lifespan is considerably longer than VFD though, although to be fair, they will probably already have lived a very long time!

 Amber/orange just feels right for me, just looks the part. But I'm showing my age here as I have used gear with glowing orange 'tube' displays when it was still current tech. 

@ gyro ,
 I see an EW604 from Feedback Test Inst. on the top shelf there, I have one as well (with the old death style binding posts too , not the recessed sockets as on yours). And I also the manual if you don 't have a copy !.

[Fungus]

Amber/orange just feels right for me, just looks the part. But I'm showing my age here as I have used gear with glowing orange 'tube' displays when it was still current tech. 

OK, as long as you add a motor to move the 7 segments backwards and forwards to match the displayed number. 

[lowimpedance]

No need for motors ! , just move head to get correct perceived/wanted number  .

[pilotchup]

I am thoroughly surprised Yellow (Orange) is doing poorly, looks the best by far IMO. Amazing how diverse the opinions are haha.

[floobydust]

OK, as long as you add a motor to move the 7 segments backwards and forwards to match the displayed number. 

I have a 7-segment display that is completely mechanical. It is from a 1970's alarm-clock radio. Backlit by #194 lamps and a mechanical shutter arrangement and a 1rpm motor.
I kept it to someday disassemble and figure out.

[james_s]

OK, as long as you add a motor to move the 7 segments backwards and forwards to match the displayed number. 

I have a 7-segment display that is completely mechanical. It is from a 1970's alarm-clock radio. Backlit by #194 lamps and a mechanical shutter arrangement and a 1rpm motor.
I kept it to someday disassemble and figure out.

I have a clock like that too, it's the only one like it I've ever seen though I did see a picture of the same mechanism in a clock radio somewhere online. I found it in a thrift store for $5 "needs repair", the bulbs were burned out of course. It seems these are exceedingly rare, it's one of my favorite clocks in my collection.

[Brumby]

My only problem with blue LEDs is not with the colour.  It's the fact that they seem to be implemented at brightness levels that approach the intensity of landing lights for a light aircraft.

SWMBO has a computer tower that has blue LEDs for power and disk activity - and, at night, they can cast a visible shadow of someone passing by on a wall 5m away.

[james_s]

Not sure if that is the case. In Toronto the public transit buses have two blue lights placed just below the roof line at the front of the cabin. They are blue, not whity washed ones. When you are waiting for a bus and look up the street you can see lights from the approaching bus in traffic at quite a distance, even at day time, so you see that a bus is coming.

Blue is easy to see, but difficult to focus on. It tends to look blurry and causes eye strain. I remember setting up the old CRT projection TVs and the blue always looked out of focus no matter how sharp it was. I see the same effect with bright blue LEDs.

[Cubdriver]

For seven segment LED stuff, I'm partial to the classics - red, green and yellow/amber.

My favorites remain nixies, followed closely by Panaplex.  Incidentally, the Panaplex stuff I have all has them filtered with red rather than amber.

This image is a bit blown out exposure-wise, but shows the red filtered Panaplex:


And this is a bare three digit Panaplex display:


I also prefer the 'dot' style LEDs that HP used to use to more conventional seven segment units:


I think it's wonderful that blue LEDs were developed, but would like to string up the designers/marketers who insist on using them at eye searing brightness on EVERYTHING!  It's supposed to be an indicator, not a cutting laser!

-Pat

[Gyro]

@ gyro ,
 I see an EW604 from Feedback Test Inst. on the top shelf there, I have one as well (with the old death style binding posts too , not the recessed sockets as on yours). And I also the manual if you don 't have a copy !.

Well spotted. It's always fun to run a curious eye over other stuff lurking in the background of photos.

Yes, I converted the deathtrap input terminals (1kV rated instrument) to shielded sockets myself. I needed to open out the holes with a step drill (or possiby taper reamer) but was able to do it carefully by hand without dismantling. I used the Hirschmann ones with threaded studs so the wiring loom can be simply transferred without modification, eg. https://uk.farnell.com/hirschmann-testmeasurement/972354101/banana-socket-32a-4mm-panel-red/dp/1011402?st=socket%204mm . Feedback did introduce the EW1604 to address the safety issue but bodged the fuseholder in a silly place on the front panel, much better keeping it at the back: https://fenix.tecnico.ulisboa.pt/downloadFile/3779571779276/LAB_IMd_Feedback_EW1604.pdf

Thanks for the offer, but there's already a scan on KO4BB... http://www.ko4bb.com/getsimple/index.php?id=download&file=06_Misc_Test_Equipment/Feedback_EW604_Electronic_Wattmeter_Service_Manual.pdf.  I've also just noticed a nice clean original PDF one at http://www.ee.bgu.ac.il/~intrlab/manuals/Feedback%20EW604.pdf.


P.S. If yours has the O/P 1VFS socket to the right of the meter movement then it's best to disconnect that too as it becomes live at high voltage (it was deleted from later meters)! 

[lowimpedance]

Thanks for the info  .The later model 1604 did remove those dangerous posts and looks like you're meter.
Will do the same mod to mine.

[xrunner]

But on the other hand why are we debating - use these in the device and pick your own color. 

https://www.adafruit.com/product/1399

[Sylvi]

Hey Bud

The TO Blue-line buses were ones that ran all night.

It is a mystery that blue lights are allowed on vehicles other than snow plows and cop cars? There seems to be zero regulation regarding vehicle lighting, now with the blue lights and silly white LEDs everywhere. Just because a municipality or big business decides to do something does not mean it is a good idea. Driving lights are a really bad idea. Daytime running lights are a bad idea. Blue LEDs are a bad idea.

On equipment, blue flourescent displays were the rage in the eighties or so, but these were a softer blue - maybe more greenish - than modern blue LEDs. Then LCDs came out and you couldn't read anything.

Another bad idea is the laser-etched text on nearly all consumer electronics and components. Burning the surface a little does not create a high-contrast print as you had with silk-screening. Sure lasers are faster and cheaper, but the panel text is invisible and part numbers are really difficult to read.

One of the nicest car interiors was a jetta from about 2016 with its red LEDs. There are too many lights inside a car but these were unobtrusive at night despite not being able to dim them.

[Gyro]

It is a mystery that blue lights are allowed on vehicles other than snow plows and cop cars? There seems to be zero regulation regarding vehicle lighting, now with the blue lights and silly white LEDs everywhere. Just because a municipality or big business decides to do something does not mean it is a good idea. Driving lights are a really bad idea. Daytime running lights are a bad idea. Blue LEDs are a bad idea.

That amazed me the first time I visited Korea. I saw trucks, large and small, displaying lights of pretty much every colour you could think of!  You'll definitely get pulled if you display blue lights in the UK (emergency vehicles as you say) and I think, Green (Doctor).