As a kid, I was very interested in Morse code. There were a few reasons for this – my father was in the Signal Corps during WW2 and his stories of how Morse was used in the war wee fascinating. I had a rather good ear for rhythms, so I learned the codes easily. Then there was the legendary Cub Scout Handbook, as used by Huey, Dewey and Louie. The Finnish publisher of Disney books actually produced one, and of course all ten-year-olds in Finland consumed it cover to cover. One feature of it were Morse codes. My best friend was very handy with electronics already at that age, so we set up a wire between our homes and Morsed our messages to each other.
Until the trash collector truck once ripped the wire.
Ooops, it’s been a while since I was last active here, sorry about that.
But to offer someting in retribution, here’s a device that can count revolutions or any other event that closes a switch, and tell you how many times that happens in a minute.
I have a need for this device, because I am building a dolly for timelapse images. The dolly has a 2m long worm screw that makes the dolly travel along an axis. If the trip takes, say, 3 hours, and the dolly carries a camera that is set to take an image every 5 seconds, we get a 3 x 60 x 20 image timelapse, ie. 4,800 images. With 25 images per second in a video, that gives you a 192 seconds, or, a little over 3 minute time lapse. During which the camera moves, you see, it’s not just a timelapse.
Accelerometers are wondrous little devices that offer boundless possibilities… as soon as you figure out a need for them.
For some time now, I have been thinking about a filament break detector for 3D printing. Filament comes in spools of 400m (1 kilogram) and they are usually hung on racks on which they rotate. The filament is fed to the printer via a small stepper motor turning a grooved feed wheel. If the filament breaks, or the feed wheel eats a notch into the filament, it will no longer enter the extruder, and the print fails. Usually the filament wire breaks if it has been exposed to air humidity for a long period – it is hygroscopic and becomes brittle.
The printers are not aware of the filament feed. There is no detector for smooth feed, and consequently any hitch in feed will fail the print. I have thought of making an optoelectronic feed detector that would shine a light on the filament spool and detect its movement, but that would require a striped disc to be attached to the spool, as well as the actual reading device installed on the rack. Then I thought of a mechanical device that would ride on the filament itself and detect its movement via rotating discs, but that soon turned out to be too complex. Continue reading Accelerometer, that tiny workhorse→
As I was kindly invited to Porvoo to speak at the Point College Internet of Things day, I thought I’d finally formalize a concept I have been thinking about for a while now: servo rotation direction and speed controlled by a potentiometer.