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| My general tinkerings – Part 3 | ||
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Description: This, believe it or not, is what could be called a "Lightning timer". Built from an old stopwatch, a 70Khz replacement crystal, and a few SMD backlight LED's; all you have to do is to start the stopwatch when you see the lightning, and stop it as soon as the thunder arrives. Due to the alternative crystal, seconds now equals 1/10ths of miles to the lightning strike :-D (PS. For readers of Electronics Weekly, I submitted this for the Gadget Freak article…) Picture Stats: Views: 1626 Filesize: 255.56kB Height: 768 Width: 1024 Posted by: Hodgkinson at June 01, 2008, 02:41:26 PM Image Linking Codes
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| Hodgkinson Posts:1080 | January 03, 2009, 07:56:03 PM Yeah, pretty much. I think the ideal crystal would have been something like 6.9? Khz (Can't remember the exact figure atm...), multiply that by 10 and it’s pretty close to the crystal I've used. Reaction times and variations in the speed of sound would probably cause more error than is present in the approximation used for the crystal frequency. It's only by chance that we had such a frequency crystal to hand; we must have been hanging onto it for years. Hodgkinson. |
| weirdami Posts:3776 | December 30, 2008, 03:15:19 PM so coincidentally the new crystal counts off speed of sound distances? |
| Hodgkinson Posts:1080 | June 02, 2008, 08:48:48 AM :-D That's the new crystal. Normal watch 32.768Khz crystals are about the size of a large seed or grain, this one on the other hand is rather larger, as you can see. It's enclosed in a glass valve-base type envlope - Hence the protective paper (Actually its that paper towel stuff used to mop up spills) |
| Chain Posts:1324 | June 02, 2008, 06:34:01 AM whats that thing in toilet paper? |