3/12/2023 0 Comments Free42 sin disappearedThis mini joy stick gives the user's left thumb super powers: I topped the 5 way switch with the stem from a miniature push button switch. The result is a rather strange looking device (see attached picture), which turns out to be unexpectedly ergonomic - for right handers at least. The common terminal of the switch becomes row header 5. These are available all over the place, PCB mounted or loose, for next to nothing and can be piggy-backed onto a 4x4 keyboard's column headers to add the functionality of a an extra row of keys. Then, I chanced upon a small 5 way switch module that is configured like a mini joy stick. In my experience, a 4x5 key module gets you into the comfort zone for a basic scientific calculator but the only low-cost, readily available keyboard of this configuration that I have seen is a self adhesive membrane unit, which makes for a quick build but offers very poor usability. I wanted to build an Arduino based RPN calculator entirely from stock sub-assemblies but not be restricted to the ubiquitous 4x4 Arduino tactile keyboard. I have turned out a little project to reawaken this thread with. Right now, the OLED display is held up at the docks but I have plenty more coachwork tasks to complete and a battery compartment to construct.ĭespite the way it looks in the last picture, I would say that 85 percent of the job is done, given the 15-20 hours spent getting a labelled keyboard up and running on a serial console test script. The attached pictures show the calculator's construction method and soldering nightmare. The result is, I reckon, aesthetically satisfactory and it is ok to use if you were able to get along with a TI59 back in the day. I took the best 36 of these to populate the keyboard and made doubly sure that they all fired at the click before I committed them to epoxy cement. I ordered up 50, 12x12 mm tactile PCB switches of a type which feature a 6 mm deep extended actuator. Making a satisfactory keyboard is the hard part. A four-line OLED display, coupled with the clean-sheet ergonomic design of HP's original machine, looked like a route to building something that would be nice to pick up and use. I decided that I would have a shot at building a functional clone of an HP35.
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