Design of the µCalc - Page 1
Forum section: electronics / general

author: apex
author_rank: Regular Contributor
timestamp: November 21, 2010, 07:46:05 pm
content: I saw the µCalc in the Episode 107.How did you get it that flat?Did you cut out the pcb for the display?What kind of battery are you using?Would like to rebuild it, but don't know how to get power on it.Or is it just driven with a solar cell?apex

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 22, 2010, 12:45:58 am
content: IIRC, Dave explained every aspects you mentioned.

author: johnboxall
author_rank: Unknown
timestamp: November 25, 2010, 08:32:40 am
content: http://www.calcwatch.com/construction.htm

author: EEVblog
author_rank: Unknown
timestamp: November 25, 2010, 10:27:06 am
content: I've explained this in one of my live shows somewhere.Yes, there is an art to getting it that thin, some careful design considerations.Two CR2016 batteries that are sandwiched between the top and bottom PCB contacts on the thin top and bottom boards.Careful LCD selection and mounting in the cutout and matching height components.Dave.

author: apex
author_rank: Regular Contributor
timestamp: November 26, 2010, 02:30:59 pm
content: OK.I think I'm understanding it now,but in the first moment it looked a bit like black magic to me.I was thinking of using LiPos but they are mostly to big.apex

author: apex
author_rank: Regular Contributor
timestamp: November 28, 2010, 07:23:54 pm
content: Thank you for the blog about it.I was thinking of putting the LCDintothe cutout to save a bit of space there,but with these DOGM-LCDs its pretty easy.apex

author: frank26080115
author_rank: Regular Contributor
timestamp: November 28, 2010, 09:06:21 pm
content: I would love to build my own, it looks like there's a full text input capability and it would be great if the microcontroller could execute MATLAB. Can such a task be accomplished with the current PIC microcontroller?

author: FreeThinker
author_rank: Frequent Contributor
timestamp: November 29, 2010, 03:17:35 pm
content: Quote from: EEVblog on November 25, 2010, 10:27:06 amThis highlights one of the problems I've found with the forum & Blogs no search facility.Could this be added easily? Would be a great help now that the forum is getting bigger.

author: dengorius
author_rank: Regular Contributor
timestamp: November 29, 2010, 05:52:31 pm
content: Quote from: FreeThinker on November 29, 2010, 03:17:35 pmWhat do you mean no search? There is a search box in the top right corner of the forum and you can find a list of all the vlogshttp://www.eevblog.com/episodes

author: FreeThinker
author_rank: Frequent Contributor
timestamp: November 29, 2010, 07:10:55 pm
content: Quote from: dengorius on November 29, 2010, 05:52:31 pmWell ok there is a search bar but it is very limited (to the point of being useless) and a more fully featured search is really required.

author: tyblu
author_rank: Frequent Contributor
timestamp: November 29, 2010, 07:21:12 pm
content: http://goo.gl/wt9wlGoogle: "uCalc site:eevblog.com"

author: EEVblog
author_rank: Unknown
timestamp: November 29, 2010, 08:13:40 pm
content: Quote from: FreeThinker on November 29, 2010, 03:17:35 pmIf there is a suitable plug-in for Wordpress and SimpleMachines, yes.If anyone has any pointer then I'll be glad to take a look.Dave.

author: TheDirty
author_rank: Frequent Contributor
timestamp: November 29, 2010, 08:14:47 pm
content: Quote from: FreeThinker on November 29, 2010, 07:10:55 pmThere's a search button on the top left that gives you a more advanced search. On the toolbar beside HOME, HELP.Still nothing for the vlogs, though.

author: Addidis
author_rank: Newbie
timestamp: November 30, 2010, 02:25:50 am
content: Any Idea when we could purchase one of these bad boys? This is the perfect calculator, small , scientific, programmable , and it uses PIC which is awesome because thats what I know. I need a calculator any way this is perfect since its soo much more.I actually like the quick connect icsp jack on there, perhaps a surface mount part between the boards ? otherwise I would still opt to leave it on.Did you break out any unused pins? this would actually be a great dev board too. Even if you just leave pads to solder headers to. This is a great design. I want one.

author: tyblu
author_rank: Frequent Contributor
timestamp: November 30, 2010, 03:24:46 am
content: Quote from: EEVblog on November 29, 2010, 08:13:40 pmMay want to try out the WP plugin "Relevanssi". I use it here:http://trajctrl.tyblu.ca. [Note that the site isn't nearly finished, so stuff the comments. I'm trying to put an old lab book online for future scholastic reference.]

author: 8086
author_rank: Super Contributor
timestamp: November 30, 2010, 08:34:19 am
content: Great video! very informativeI'm actually working on a credit card sized data logger right now, so this was very useful. Might have to check out that LCD.

author: teedeeus
author_rank: Newbie
timestamp: December 02, 2010, 10:06:53 pm
content: David,Awesome!!!I am fascinated by the touch keypad you are using on the uCalc. It looks awesome. How well does it work? is it easy to mis-type keys when using it? Do you have to get your fingers perfectly in the solder-mask circles? Also, could you give me some pointers on using touch sensors with PICs? I have noticed that alot of PICs now list "touch" on the pin descriptions, but as I am totally used to arduino and know almost nothing about PICs, where do I start?-teedeeus

author: tyblu
author_rank: Frequent Contributor
timestamp: December 03, 2010, 12:25:01 am
content: If you want to use Microchip's stuff, try out one of their touch dev kits:http://goo.gl/ggBsI

author: teedeeus
author_rank: Newbie
timestamp: December 03, 2010, 03:48:29 am
content: Quote from: tyblu on December 03, 2010, 12:25:01 amThanks for that. I appreciate it.-teedeeus

author: the_raptor
author_rank: Regular Contributor
timestamp: December 03, 2010, 12:56:28 pm
content: Hey Dave you know this video means you have to finish the µCalc right?With a dust proof container this would be much more handy for me at uni then the µwatch or carrying a full sized scientific calculator around.

author: scrat
author_rank: Frequent Contributor
timestamp: December 03, 2010, 02:26:57 pm
content: Quote from: frank26080115 on November 28, 2010, 09:06:21 pmOf course no, such an MCU can't execute MATLAB! However, one could implement a very simple interpreter emulating some Matlab-like behaviour, but it is not an easy task, limited memory, for example, would be an issue.

author: teedeeus
author_rank: Newbie
timestamp: December 04, 2010, 05:42:31 am
content: Dave,I want the uCalc sooooo bad. Any chance you would open source your design files and provide the link when it's done? Any possibility you might make this into a kit? I do know how to solder surface mount components-teedeeus

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: December 04, 2010, 12:02:14 pm
content: Quote from: the_raptor on December 03, 2010, 12:56:28 pmDave, let me guess how this went - lots of enthusiasm to get a nice hardware & mechanical design, built the board, wrote enough SW to test the hardware, but then got bored at the prospect of writing all the software...?I often get the same thing - I _love_ doing hardware & mechanical design but getting stuck into the software tends to be a far less exciting prospect... Once I get stuck into it, it's usually OK, but I tend to get very easily distracted into doing anything else apart from getting started.I wonder if the answer might be to build a few & let someone with more software enthusiasm do some software in exchange for splitting the proceeds of sales?BTW for the detail of connecting the top/bottom battery contact, a small leaf-spring contact type arrangement would probably be the ideal solution.Also, instead of gluing together, which is a bit permanant, I wonder if there are some tiny screws you could use, or maybe rivets, which could be drilled out.Another option may be careful use of hot-melt inside cavities in the inner core spacer , which would allow seperation by applying heat - maybe have some thermal vias in the rear cover to make this simpler.Or larger holes in the rear, into which the hotmelt is injected while the sandwich is clamped together.

author: frank26080115
author_rank: Regular Contributor
timestamp: December 11, 2010, 02:05:57 am
content: Quote from: mikeselectricstuff on December 04, 2010, 12:02:14 pmI have the opposite problem, I breadboard something, and then write (what I think is great) software for it, and then never build a finished "product". Mainly because I'm a poor student who can't afford too much hardware.QuoteHow about using solder? Have copper on the edge and solder the two halves together. This might not last after several reassemblies though.

author: David
author_rank: Frequent Contributor
timestamp: December 19, 2010, 09:55:47 pm
content: Dave - What is the nominal current load when the device is in use? How long a battery life do you expect?

author: WattSekunde
author_rank: Regular Contributor
timestamp: December 19, 2010, 11:37:21 pm
content: Wow! I like the µCalc design very much.But I really miss a piezo for the key click. Click not beep! I hate beeping keys.If I use a calc the keyboard feedback is important for fast and secure usage. I am a long time HP48SX user.I think there is enough room for a small piezo.If you sometimes think of selling the µCalc I would prefer to buy a DIY kit with pcbs and parts.Thank's for your always inspiring EEVblog!Michael (WattSekunde)