Easy 7 segment display filters

Are you building a cockpit, planning to build one or just dreaming, this is your cockpit builder meeting point

Moderators: russ, Ralph

Post Reply
Message
Author
User avatar
jph
Posts: 2846
Joined: Fri Apr 10, 2020 12:50 pm
Location: Somewhere over the rainbow..

Easy 7 segment display filters

#1 Post by jph »

A pet hate of mine is any 7 segment display that you can clearly see the unlit digits.
I see it on so many builds. I have been experimenting with various different materials for filtering and have decided that, after experimentation, the best overall is the same material that is used by the dubious 'yoof' / 'yobbo' boy racers' to tint their perfectly good headlights and hide their perfectly useful taillights ;)
'Headlight tint film' is available almost universally in differing shades and is available in matt finish. It is absolutely excellent for white, red and orange led displays. Most car accessory shops sell the stuff. The stuff here is from aliexpress as I was ordering some other junk so added it to try. It is also designed to be able to filter light, It is actually very good for allowing red and orange to pass through (for car tail lights) . You can use very dark tint on those colours if you wanted although this is perfectly acceptable to me.
It can be applied directly over the led display as it is self adhesive but it probably better applied onto a small thing sheet of lexan. Either way, it does a super job.

Here is a white 6 digit 7 segment display, well, 2 of them. The top one is NOT POWERED AT ALL ! . They are held up to bright sunlight through the window.
.
The lower one has one layer of a cheap matt finish black tint film applied with around half brightness at 5V on a TM1637 driver driven from the STM32 Nucleo.
It actually gives the display a very slight 'cold' look which is very much akin to a Boeing MCP display colour.
The image here looks to 'bloom' or smudge, I assure you it absolutely does not, is is crystal clear, it is simply my absolutely crappy Moto G5 phone - but it goes ring ring, when I bother to turn it on, so no reason to change it..
Very effective filtering
display filter.jpg
.
this is the stuff I used here - it is the centre selection "Matt Black" - but I am sure similar stuff is available at your local car spares shop.
https://www.aliexpress.com/item/1005004 ... 1802d7JE0j
Car-Light-Film-Car-Headlight-Fog-Light-Taillight-Smoke-Black-Tint-Vinyl-Film-Self-Adhesive-Motorcycle.jpg_640x640.jpg

This is the type of thing that looks horrible with plain displays on view - absolutely no filtering - ruining the realism imho.
Image taken randomly from a web search -
.

psp737digits.jpg
Joe
Joe. CISSP, MSc.

User avatar
Keith Baxter
Posts: 4674
Joined: Wed Dec 20, 2017 11:00 am
Location: Botswana

Re: Easy 7 segment display filters

#2 Post by Keith Baxter »

Joe,

If you want the actual data sheets for the radios. It gives you size and color font etc

https://www.gableseng.com/wp-content/up ... 04-124.pdf


https://www.gableseng.com/products/product-tag/b737/


Keith
AMD RYZEN 9 5950X CPU, Corsair H80I cooler, ASUS TUF GAMING B550-PLUS AMD Ryzen Mother Board,  32Gb ram Corsair Vengeance 3000Mh, MSI GTX960 4G graphics card 

User avatar
jph
Posts: 2846
Joined: Fri Apr 10, 2020 12:50 pm
Location: Somewhere over the rainbow..

Re: Easy 7 segment display filters

#3 Post by jph »

Thanks for that Keith, great info.
I already had the general display sizes and have samples of the displays - some literally arrived this morning !. They are direct from the manufacturer in China. (via Alibaba - not aliexpress)
Here are a couple of pics of the 6 and 5 digit unit.
I enquired about a non 'angled' character - as in a straight up and down digit - but they would be specially made and I am simply not paying for that ;)
These are really neat. Perfect size as well.
These arrived about an hour ago..
6 digit W R O B.jpg
these I have had for a while..
5 digit R O.jpg
Joe
Joe. CISSP, MSc.

User avatar
Ralph
Posts: 7878
Joined: Tue Oct 27, 2015 7:02 pm
Location: De Steeg
Contact:

Re: Easy 7 segment display filters

#4 Post by Ralph »

Nice one! I have a Davtron M307 here, it looks a bit like what they are using: https://www.davtron.com/product-detail.php?M307FC-6
That was also very thin and the same type of color / material.

User avatar
jph
Posts: 2846
Joined: Fri Apr 10, 2020 12:50 pm
Location: Somewhere over the rainbow..

Re: Easy 7 segment display filters

#5 Post by jph »

It probably is, it is actually ideal as the companies designing it, well, the good ones, needed to ensure that 2 criteria were met, first, it acted as a blackout to disguise the original colouring and 2, that when illuminated it did actually allow white red and orange to shine through well. It is fine with yellow as well.
Those criteria are exactly what we require. The fact that 'matt' finish is available is excellent also. It is also extremely tough and hard wearing as it is designed to be fitted to the exterior of a vehicle. It is very difficult to scratch or mark with normal cleaning or with a fingernail.
most LED Segments are epoxy filled as I found out when talking to the factory, and this means that the surface is not totally flat but that doesn't seem to cause an issue with the film as it is quite thick.
I have been playing around with different filters for the better part of a year now and this is the best I have found by far.
I am going to have a look locally and buy whatever samples I can get in the way of matt finish of different shades. On non white colours - RED, ORANGE, YELLOW then you can go much darker if needed as they pass though extremely well although it is probably not needed as those colours also do not use the very prominent yellow epoxy filling of the bright white units so are far easier to mask / filter. The fist image of the displays above show 20 high brightness white 0.3" units, they are the ones with the very obvious yellowish coloured epoxy, and the most difficult to mask. The other 7 in the image are actually samples from the manufacturer of different oranges, red and possibly a yellow and blue. I can't remember exactly what they sent. The second image are all of 0.3" 'red' 5 segment units.
ALL of the non white colours have a much less visible segment epoxy to start with so are much much easier to filter. win win.
Joe. CISSP, MSc.

JackZ
Posts: 2262
Joined: Mon Feb 22, 2016 1:02 pm

Re: Easy 7 segment display filters

#6 Post by JackZ »

Nice find
My YouTube Chanel on the A320 (Real SOPs by an Airline Pilot IRL):
https://www.youtube.com/playlist?list=P ... 0Q6SBASRqJ

Kaellis991
Posts: 581
Joined: Mon Sep 07, 2020 8:49 am

Re: Easy 7 segment display filters

#7 Post by Kaellis991 »

Hey Joe,

For those 5 and 6 digit displays that are not mounted to a max7219 board, how do you wire them up?

Kirk

Post Reply