Post by thread:[EE]: light wands

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Was browsing thinkgeek http://www.thinkgeek.com when I came across this neat little device. It seems to be a lightwriter, (I think I've heard these discussed on the list before) but their description confuses me a little. I understand the concept in principle, it's pretty simple to build something like this (i.e. Tony's propeller clock), but this excerpt shows the problem I have with it: "Fantazein has a rapidly oscillating wand carrying tiny lights (LED's) at its tip that creates the rare display. As the wand whips through space, the LED's shimmer at megahertz speed so that you see their light but cannot see the wand" Megahertz speeds? From a mechanical oscillator? How would the stresses not tear it appart? Or is this just miswritten? Regards, - --Brendan -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 6.5.8 for non-commercial use <http://www.pgp.com> iQA/AwUBPV05EgVk8xtQuK+BEQJgjwCg6L4rUyosVTb9EhySWedIVvqIyWwAmQFO GADWNl/sgjsQhqTDsuQlnfs0 =uWku -----END PGP SIGNATURE----- -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> "Fantazein has a rapidly oscillating wand carrying tiny lights > (LED's) at its tip that creates the rare display. As the wand whips > through space, the LED's shimmer at megahertz speed so that you see > their light but cannot see the wand" > > Megahertz speeds? From a mechanical oscillator? How would the > stresses not tear it appart? Or is this just miswritten? They probably refer to the speed at which the LEDs are switched to create the image. Add a bit of sales talk (hey, this works like a TV, right? A TV video signal is a few MHz, right? OK, I know what to write!) Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: http://www.voti.nl consultancy, development, PICmicro products -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Could it be the difference between wand speed and LED switching speed? Whatever the wand sweep rate, the LED's would have to be modulated at a minimum of sweep rate * 2(Back + Forth) * Horiz Res. If you want to blank the dots in between as Olin suggested, you can double the rate again. Of course, the undertermined factor here is how fast you can whip your wand. Lyle H >On the order of .0001 MHz (100's of Hz) is more like it. > >Perhaps this is just a case of "create spec writing" ... > >RF Jim {Original Message removed}

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 > On the order of .0001 MHz (100's of Hz) is more like it. > > Perhaps this is just a case of "create spec writing" ... My guess was more along the lines of "if you sum the blink rates of all the LEDs together, then they blink at several MHz I didn't believe that a piece of plastic could move at MHz without failing rapildy. - --Brendan -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 6.5.8 for non-commercial use <http://www.pgp.com> iQA/AwUBPV1AOAVk8xtQuK+BEQJuTQCfTTscCE4vSPuJaCEdXfxxfLk679IAn1b5 PrSQtP0swZbH9tU6f/nVcNjF =t8hc -----END PGP SIGNATURE----- -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

{Quote hidden}> -----Original Message----- > From: Brendan Moran [SMTP:spam_OUTbmoranTakeThisOuTMILLENNIUM.CA] > Sent: Friday, August 16, 2002 7:11 PM > To: .....PICLISTKILLspam@spam@MITVMA.MIT.EDU > Subject: Re: [EE]: light wands > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > > On the order of .0001 MHz (100's of Hz) is more like it. > > > > Perhaps this is just a case of "create spec writing" ... > > My guess was more along the lines of "if you sum the blink rates of > all the LEDs together, then they blink at several MHz > > I didn't believe that a piece of plastic could move at MHz without > failing rapildy. > > - --Brendan > Well, it does say that "the LED's shimmer at MHz speed", not the plastic wand. Regards Mike -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 > Well, it does say that "the LED's shimmer at MHz speed", not the > plastic wand. True enough, but it's still a bit misleading... And, anyway, being a bit of a picster myself ;) If I want something like that, I'll have a lot more fun building it than buying it :D - --Brendan -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 6.5.8 for non-commercial use <http://www.pgp.com> iQA/AwUBPWEhggVk8xtQuK+BEQLyrQCfcJY8afvqRWuSWl9BSYK95rvteMUAoJBA rHMqxEUjE28FVuiT0B+lL9sY =SXku -----END PGP SIGNATURE----- -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam.....mitvma.mit.edu