On Wed, May 30, 2007 10:30 am, Gus Wirth wrote: > Lan Barnes wrote: >> On Tue, May 29, 2007 10:07 pm, Tom Gal wrote: >>> Speaking of software guys...... >>> >>> <Hardware Hat> >>> >>> >>>> Next if you get serious just go to the net and use either >>>> http://www.mouser.com/ or >>>> http://www.digikey.com/ >>> >>> >>> Yep, and if digikey doesn't have it (can't say I checked mouser), >>> probably >>> no local store will. Why are you using 0.9 volts? >>> >>> >> >> Because my battery is a fracking ice tray with ten pennies and >> galvanized >> washers hanging in brine. This is a SCIENCE PROJECT. >> >> However, it isn't particularly mature to snap at people offering help, >> even if the OP has slipped from memory. >> >> So ... >> >> - I don't have time to go on line. I need it today. >> >> - I might be able to increase the voltage by adding up to 4 more cells >> scaling (in a perfect world where I don't live) to 1.26 V. >> >> So as delightful as it is to reminisce about fond memories of Gateway, I >> think I'll go to Fry's (search parties after 24 hrs if I fail to report >> in) and buy the lowest voltage LED they have, and maybe to Home Depot to >> shag a few more washers. >> >> The project has to be ready to present Thursday morning. >> >> Thanks to all who answered. It was especially important to learn that >> 0.9V >> is unlikely to work. Saves us the frustration of a failure w/o a clue. > > Why does your indicator device have to be an LED? > > A simple multimeter (I have one you can borrow) is a good indicator and > works down to at least 0.1VDC. Or you can switch to current and measure > the current through some load like a resistor. >
We have the voltmeter (el cheapo Harbor Freight) as part of the display so people can test different potentials across different banks of cells. That's how we know it's at 0.9 V. The LED has kwel shiny appeal. The project manager, an 11-yr-old, wants an LED. Tech must do what Marketing wants, and do it by tomorrow morning. > Or you can do the classic experiment that Oersted did[1]. I have all the > parts for that also. > This is mostly built and must be finished tonight. Tomorrow morning. > Gus > > [1] Run the wire next to a compass and notice the compass needle move. > This is the forerunner of the galvanometer. > > Good thought, no compass. Also requires a momentary switch. Did I mention tomorrow morning? -- Lan Barnes SCM Analyst Linux Guy Tcl/Tk Enthusiast Biodiesel Brewer -- [email protected] http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
