Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!samsung!munnari.oz.au!basser!metro!natmlab.dap.csiro.au!ditsyda!macuni!mqccsunc!ifarqhar From: ifarqhar@mqccsunc.mqcc.mq.OZ (Ian Farquhar) Newsgroups: sci.electronics Subject: Re: Christmas Lights Keywords: engineering overkill Message-ID: <52@macuni.mqcc.mq.oz> Date: 18 Dec 89 11:54:04 GMT References: <1840021@hpsad.HP.COM> Sender: news@macuni.mqcc.mq.oz Reply-To: ifarqhar@mqccsunc.mq.oz (Ian Farquhar) Organization: Macquarie University, Sydney Lines: 31 In article <1840021@hpsad.HP.COM> billk@hpsad.HP.COM (Bill Katz) writes: > > You want to talk about overkill in blinking lights... I have an >8749 that runs 16 different patterns on a string of 16 LEDs. The catch is >you do have to run a wire to each one. But that wasn't good enough. > The mark 2 light blinker is a 68000 that can do 60 or 70 different >effects on a 16 by 64 array of LEDs. I use this as part of a halloween >costume. Of course with only 1024 solid state relays it would be possible >to run an array of Christmas bulbs. > This is the best example of engineering overkill that I have yet heard of! A 68000 to flash a few lights (running UNIX, maybe? :-) I hope you are joking. Oh, well... I remember that when I was involved in an astronomy project to design a wall chart, we used these clever little leds that had (I think) a 3909 chip in them. (The 3909 is a LED Flasher chip, quite clever). We discovered that by varying the voltage, we could quite accurately vary the flash rate at the start, though manufacturing differences got them out of sync after a couple of minutes. A christmas tree made out of these would be very easy: a 5V supply (if my memory serves me correctly) running along some thin green figure 8. The other really nice thing is that these LED's drew such a small current, that a short would not be a fire hazard! Of course, you would not get the nice effects, but then it wouldn't have a MIP behind it either! D