Keypad With Numeric Display - Page 1
Forum section: electronics / general

author: MudAndSnow
author_rank: Contributor
timestamp: August 25, 2018, 11:10:17 pm
content: Hello,This being my 1st post, I'll start with a thank you to the all the posters. I have learned a lot from reading this forum.Summary:I want a keypad with numeric display in a wall mountable enclosure with extra space in the enclosure for my electronics. It is so common on microwave ovens, security alarm panels, etc that I wonder if I am being wasteful making my own. Does it sound feasible to find someone who makes a similar product and get a custom one from them?Where would I find someone to make one for me?At what quantity would it become cheaper to get a custom one vs make it myself?Details:I have been working with electronics for a bit over a decade and am finally making a product of my own with plans to put it on kickstarter. Part of it involves a timer. I need a way for users to enter a time and view it on a display. I have made 1st version using an off the shelf 4x4 matrix keypad and 4 digit 7 segment display. Now I am working on the enclosure for it. Plan is to build a vacuformer and make it out of ABS but I worry I am being wasteful 'reinventing the wheel' or in this case, reinventing the microwave oven faceplate.I like the thought of making it myself because I have more control and less risk but I would also like to be ready to produce a lot of units very quickly just in case my ks campaign goes as well as I am hoping. I also want to get the lowest cost possible to make it less likely to be copied.

author: james_s
author_rank: Super Contributor
timestamp: August 25, 2018, 11:21:27 pm
content: I'm not aware of any off the shelf options like this, these are normally custom made for the specific application.Another option if you want to get really fancy is get some proper key switches and do a PCB for them and the display. There are some types you can get custom printed keycaps for.

author: MudAndSnow
author_rank: Contributor
timestamp: August 25, 2018, 11:30:19 pm
content: Thanks for your reply.What kind of costs would you expect for a custom made faceplate and enclosure?I made a PCB for the 7seg and was planning on putting buttons on it too but opted for this off the shelf keypad because it was cheaper and easier.https://www.aliexpress.com/item/16-Key-Membrane-Switch-Keypad-4X4-Matrix-Keyboard-for-arduino-Diy-Kit/32874565775.html?src=google&albslr=222300373&src=google&albch=shopping&acnt=708-803-3821&isdl=y&aff_short_key=UneMJZVf&albcp=658707750&albag=38901860132&slnk=&trgt=61865531738&plac=&crea=en32874565775&netw=g&device=c&mtctp=&albbt=Google_7_shopping&aff_platform=google&gclid=CjwKCAjw_IPcBRAjEiwAl44Qkc_UWkEGhUhrVzQjBrAyudwx6lV1vmt_nmYTaroMJgHf5ucbo1ZcnRoCTfwQAvD_BwE&gclsrc=aw.ds

author: james_s
author_rank: Super Contributor
timestamp: August 26, 2018, 12:05:50 am
content: I have no idea, it's going to depend on the cost of the materials you select. Key switches can be dirt cheap or they can be fancy high quality Cherry keyboard switches or industrial switches.

author: admiralk
author_rank: Regular Contributor
timestamp: August 26, 2018, 01:24:15 am
content: Quote from: MudAndSnow on August 25, 2018, 11:10:17 pmWhy not use an LCD with a touch screen? I thought about using one ofthesefor a project, but the project requires a smaller screen. They are supposed to be relatively cheap?

author: MudAndSnow
author_rank: Contributor
timestamp: August 26, 2018, 02:06:20 am
content: Thank you for the recommendations. My goals are low cost, good reliability and low power use (in that order). I think bubble keypad and 7seg LED display are the best for that. That seems to be the common way microwave oven displays are made so based on that and on my own searches for parts, I think those are the best electronics. I'm still open to other ideas though if you know of something cheaper.Ideally I will get a custom bubble keypad but the generic ones will suffice if custom costs too much.What I am mostly struggling with is the enclosure. Should I make my own enclosure, get someone else to make the enclosure or find someone who makes similar products and get them to make enclosure and electronics? Perhaps I should do all 3, start with diy until I get sales and then farm it out. That is pretty much what I am planning but as diy costs are adding up I'm wondering if I should bother making a vacuformer or just skip diy phase and farm it out sooner than later.

author: james_s
author_rank: Super Contributor
timestamp: August 26, 2018, 03:55:34 am
content: How many do you plan on building? Custom manufactured membrane keypad will probably be pretty expensive per unit until you reach a few thousand units at least.

author: MudAndSnow
author_rank: Contributor
timestamp: August 26, 2018, 04:36:38 am
content: Thanks for the estimate. I have no idea how many I am going to build. Id like to set ks min low, about 100 units. But thats only if I can build it myself for reasonable cost. If not then I'll set min to whatever is required to pay for tooling, etc. I'd like to be somewhat ready to make millions just on the off chance things go as well as I hope.

author: Ian.M
author_rank: Super Contributor
timestamp: August 26, 2018, 07:19:41 am
content: Its possible to do small run custom keypads with a fairly low setup cost. Instead of using a membrane, one uses a PCB with tactile dome switches:https://www2.mouser.com/new/keystone/keystone-key-pad-dome-switches/For the top layer, talk to a local sign shop for custom printed laminated self-adhesive vinyl.

author: ebastler
author_rank: Super Contributor
timestamp: August 26, 2018, 07:56:12 am
content: Just a thought: The "modern" way of providing a low-cost user interface would be to just put Bluetooth, NFC, or WiFi into your gadget, and expect the user to connect via their smartphone.I am not necessarily a fan of this approach. If the timer in your device needs to be set to a different value every time it is used, using the phone would be quite impractical. But if changing the timer value is an infrequent configuration step, and normally one just presses a single start button, configuration via phone might actually improve usability: It separates the interfaces for setup vs. regular use, and provides more flexibility and a nice graphical interface available for the setup.

author: MudAndSnow
author_rank: Contributor
timestamp: August 26, 2018, 08:27:28 am
content: Quote from: Ian.M on August 26, 2018, 07:19:41 amGood ideas. Thank you.

author: MudAndSnow
author_rank: Contributor
timestamp: August 26, 2018, 08:36:01 am
content: Quote from: ebastler on August 26, 2018, 07:56:12 amThanks for the idea. WiFi is on the list for future features. For now I want it as simple as possible since it is my first product and my funding and time are limited. HW is much simplier for me than apps.

author: james_s
author_rank: Super Contributor
timestamp: August 26, 2018, 04:23:58 pm
content: Actually now that you mention it, it does seem I came across a company somewhere that would custom print various front panels including keypad overlays. I can't remember what the place was called but I think it was somewhere that sold enclosures.

author: mdszy
author_rank: Unknown
timestamp: August 26, 2018, 06:18:28 pm
content: Quote from: ebastler on August 26, 2018, 07:56:12 amDamn, when it's put that way it's pretty fascinating that it's a bit cheaper to develop a simple wireless solution with an android application and bluetooth module than it is to make a simple keypad...

author: MudAndSnow
author_rank: Contributor
timestamp: August 26, 2018, 07:49:46 pm
content: Quote from: mdszy on August 26, 2018, 06:18:28 pmI often encourage my bosses to release a simple product first and add features later. They rarely listen and they often complain it takes way too long to release products. This is my chance to finally do it my way, make it simple and solid and get sales asap.WiFi would be cool but it will take longer to develop and probably cost more, specially if you include support for WiFi and app issues.

author: ar__systems
author_rank: Frequent Contributor
timestamp: August 27, 2018, 01:09:59 pm
content: Quote from: mdszy on August 26, 2018, 06:18:28 pmIt is not cheaper. I can add a keypad and 4x7seg LED display to a device for a under 5 bucks per unit, and a few days of work. Bluetooth module will cost you substantially more, and good luck making a decently looking Android + iPhone apps in that time.Not to mention the impact on user interface. Forcing UI through the phone means you have to have the phone, and have an app running.To give you an example - how would you like to have to use your phone to turn on the light every time you go to a washroom?

author: MudAndSnow
author_rank: Contributor
timestamp: August 27, 2018, 03:22:49 pm
content: Quote from: ar__systems on August 27, 2018, 01:09:59 pmWhat do you use for an enclosure for keypad and display?

author: ebastler
author_rank: Super Contributor
timestamp: August 27, 2018, 04:53:33 pm
content: Quote from: ar__systems on August 27, 2018, 01:09:59 pmA Bluetooth module costs 2 bucks, in single (!) quantity, and that's just looking on ebay. Search for CC2540, CC2541 for example.Regarding the development costs -- if you are doing this for money, selling a small quantity of a cheap device won't cut it in any case. If you are shooting for larger quantity, it might be worthwhile to invest the extra development time, come up with a nicer interface, and sell more units?QuoteThat is the more valid concern in my book, and I mentioned it in my post when I first brought up this option. A smartphone interface is not the right choice if it is needed foreveryuse of asimpledevice. (It will make more sense if it is needed for configuration only, or for a more complex gadget which requires a more involved user interface anyway.)

author: thm_w
author_rank: Super Contributor
timestamp: August 27, 2018, 09:49:23 pm
content: Quote from: admiralk on August 26, 2018, 01:24:15 amTouch screen would certainly be the lowest cost for small volume (<20 pc).https://www.aliexpress.com/item/3-2-inch-TFT-LCD-Touch-Screen-Module-Display-Ultra-HD-320X240-ILI9341-for-3-2/32808968215.html100pc you start entering custom membrane level. NRI would be $200-500. Per numpad cost might be $2-5. So very rough estimate, $8-10 per piece for 100pc. Best to get a quote if you are seriously considering it:https://www.alibaba.com/product-detail/OEM-Service-PET-Membrane-keypad-with_60701207062.htmlThe feel will be a bit cheap with normal plastic switch, if you want a good feel you'd have to use the tactile domes as mentioned above which will increase the cost a bit. But reliability can be OK with properly spec'd materials.Then you'd still need some rigid material to go on the back and a cutout for the 7-seg display.

author: MudAndSnow
author_rank: Contributor
timestamp: August 28, 2018, 05:56:34 am
content: Quote from: thm_w on August 27, 2018, 09:49:23 pmThats what Ive been looking for. Seems like 'oem service' is a good search term on Alibaba. Thank you. Now I just need to dig around in seaches like 'oem service keypad enclosure'.Speaking of rigid material for keypad backing, cheapest 5mm abs sheets I could find were about 5-10$/sq ft at low quantities. Does that price and thickness sound reasonable?