Cost effective alternative to disappearing 7segment led displays? - Page 1
Forum section: electronics / projects

author: V_King
author_rank: Regular Contributor
timestamp: March 07, 2022, 10:35:53 am
content: Hello,I am looking into designing a small handheld sensor interface board with some 3d printed enclosure, to be able to use it in field.My only experience with portable information visualisation dates back 7-8 years ago using 7segment displays, everything else, just feeds data back via serial into PC UI.Looking at current stocks of the usual distributors, it looks like 7segment led displays had their time and the choice is diminishing. What are the alternatives, which do not require a massive MCU just to drive the shiny new amoled display? I need to show 4 digits, 25-30mm height, to be readable in bright sunlight and power consumption is NOT an issue.I initially looked at the ebay etc, to see what's the popular choice for arduinos etc, but OLED displays are tiny and very quickly get expensive, little TFTs easily available are very dim, and I am looking into working with graphics libraries. Everything becoming very complicated very quickly.What is the go to solution for in such cases nowadays? Trying to avoid large initial time investment, but future availability is important. I will only need 10-50pcs/year but for the foreseeable future (10years minimum). Am I looking at all time buy of 7seg displays collecting dust at distributors?All suggestions are much appreciated, just please restrain from off topics!

author: max_torque
author_rank: Super Contributor
timestamp: March 07, 2022, 11:52:41 am
content: How certain are you of your future volumes?I think i'd just buy what i needed now (500 pieces?) and put them on the shelf

author: TheMG
author_rank: Frequent Contributor
timestamp: March 07, 2022, 02:34:59 pm
content: What about a good old fashioned transflective character LCD display module? They are still easy to get and easy as pie do drive from even the most basic micros.

author: mc172
author_rank: Frequent Contributor
timestamp: March 07, 2022, 03:06:50 pm
content: A quick look on the Farnell website shows over 600 different 7-seg options with at least 60 (10%) of those examples showing over a thousand currently in stock:https://uk.farnell.com/c/optoelectronics-displays/displays/led-displays/7-segment-led-displaysCompletely tangentially, I see their website has got a "buyer view" and "engineer view" option... I hope they don't also go the way of RS.

author: DavidAlfa
author_rank: Super Contributor
timestamp: March 07, 2022, 04:05:56 pm
content: Hard to beat extreme low power consumption of monochrome LCDs.There're cheap OLEDs:www.aliexpress.com/item/33039948724.htmlBut avoid them if you're going to use them for long runs, they'll burn out in few 100s of hours.7-segment style:www.aliexpress.com/item/32885549612.htmlGraphicals:http://www.aliexpress.com/item/1005001874222316.htmlhttp://www.aliexpress.com/item/4000405829029.htmlIf buying large quantities, check them at Alibaba, you'll get much better prices.

author: V_King
author_rank: Regular Contributor
timestamp: March 07, 2022, 07:47:25 pm
content: TheMG and DavidAlfa, thank you very much for the pointers! I completely forgot about those screens. I think they will be the winners for this application. I just need to find a good bright option in the jungles of Alibaba.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 07, 2022, 08:01:28 pm
content: With a 3d printed case, just separe LEDs on a PCB may be an option - so 7 seg LED in DIY mode. Even intensity can still be a bit tricky.

author: jiarui
author_rank: Contributor
timestamp: March 07, 2022, 08:19:16 pm
content: You could also consider using the WS2812/SK6812 LEDs to create your own 7 segment display. Each digit will need 20 chips, at around $.1 each. These chips are designed for lighting use. They can get quite bright. You'll need only 1 output pin of your micro to control them. Because data stream is fairly timing sensitive, it may be a little tricky writing the code to send the data to them. There are Arduino libraries available for working them them.

author: Benta
author_rank: Super Contributor
timestamp: March 07, 2022, 08:48:53 pm
content: Quote from: TheMG on March 07, 2022, 02:34:59 pmI second this. Easy to read in sunlight, and if necessary a backlight for operation in the dark.

author: TimFox
author_rank: Super Contributor
timestamp: March 07, 2022, 08:53:21 pm
content: I admit to liking self-luminous displays such as 7-segment LEDs, despite their power consumption.Mouser has quite a few 7-segment LEDs in stock from Wurth:https://www.mouser.com/c/optoelectronics/displays/?product=7-Segment%20Display&product%20type=LED%20Displays&instock=y

author: nali
author_rank: Frequent Contributor
timestamp: March 07, 2022, 09:37:13 pm
content: I vote transflective LCD. Even LEDs are hard to read in bright, direct sunlight unless you manage to find some nice high brightness displays, but by then you're probably appraching the cost of a LCD anyway.As for the stock, I'd just buy it. A couple of grand extra upfront for component costs is pretty cheap to guarantee the lifetime of your product IMHO. And... you'll be buying them eventually anyway, probably at a higher price the way things are going

author: Haenk
author_rank: Super Contributor
timestamp: March 08, 2022, 01:17:13 pm
content: Those "standard" dot matrix LCD (1602) are really cheap, like 2USD. For a mobile application, that would be the best replacement, I guess.

author: V_King
author_rank: Regular Contributor
timestamp: March 08, 2022, 01:24:54 pm
content: Thanks everyone with suggestions, just please keep in mind I need 25-30mm height digits, which reduce the choice considerably!

author: DavidAlfa
author_rank: Super Contributor
timestamp: March 08, 2022, 06:01:02 pm
content: Comparing the second graphical LCD I posted (fixed the links) with other 2.4" modules, it seems to use 0.35-0.38mm pixels.So 128x64 gives a viewing area of 44.8x22.4mm ... 48.6x24.3mm , pretty close to what you need.In these cases, better to get one for testing and checking yourself.

author: voltsandjolts
author_rank: Unknown
timestamp: March 08, 2022, 06:06:29 pm
content: Quote from: V_King on March 08, 2022, 01:24:54 pmDigi-Key have 6 options for 1" 7-seg led displays, with a total stock of around 12,000 of these items.These type of parts will be around for years to come.

author: DavidAlfa
author_rank: Super Contributor
timestamp: March 10, 2022, 03:25:42 am
content: 7-segment displays are still strong...1.2", 10pcs, € 2,97($3.28)https://a.aliexpress.com/_uJ32hp4-digit 1.2” at Alibaba:https://m.alibaba.com/product/60530528178/1-2-inch-large-4-digit.html

author: mariush
author_rank: Super Contributor
timestamp: March 10, 2022, 05:35:05 am
content: You could also just go to a LCD display manufacturer and pay to have your custom LCD screen made.Dave made a series of videos about this ... costs you a few hundred dollars for the initial design/prototype/a few lcd screens for your review and then if you're satisfied, order big batches they can be quite cheap.A transflective display would be ideal (great for daylight view), and you could add a couple leds on the sides as a backlight option.May also want to look at e-ink ... can get them for 3$ or less if you buy 1000 pcs or more.ex1.54" 152x152 px :https://www.alibaba.com/product-detail/1-54-White-Black-152x152-SSD1675_1600083675479.html2.13" 122x250 px :https://www.alibaba.com/product-detail/2-13-E-ink-Paper-Electronic_62077324905.html