| wpwrak | grmbl. i wonder what they make telephone cables from around here. painted dirt ? a circuit with a current consumption of about 20-30 mA drops some 300 mV across 2*~2m of such cable. so that's around 2-4 Ohm/m. | 18:06 |
|---|---|---|
| DocScrutinizer05 | lol | 19:45 |
| DocScrutinizer05 | 1.7E-6 ohm*cm | 19:49 |
| DocScrutinizer05 | ~1.7 * 10**-6 / 0.05 / 0.05 * 400 | 19:51 |
| infobot | 0.272 | 19:51 |
| DocScrutinizer05 | ohms for 4 m of 0.5*0.5mm (square) wire | 19:52 |
| DocScrutinizer05 | ~30 * 10**-3 * 0.272 | 19:53 |
| infobot | 0.00816 | 19:53 |
| DocScrutinizer05 | ~30 * 10**-3 * 4 * 4 | 19:54 |
| infobot | 0.48 | 19:54 |
| DocScrutinizer05 | err | 19:54 |
| DocScrutinizer05 | no err | 19:55 |
| DocScrutinizer05 | 4R * 4m | 19:55 |
| DocScrutinizer05 | vs 0.272R @ 4m | 19:55 |
| DocScrutinizer05 | ~1.7 * 10**-6 / 0.02 / 0.02 * 400 | 19:56 |
| infobot | 1.7 | 19:56 |
| wpwrak | heh, (0.5 mm)^2. i wish :) | 20:01 |
| wpwrak | but when i compare with the same sort of wire they sell at digi-key, it's still an order of magnitude off. very suspicious. | 20:01 |
| wpwrak | maybe they used aluminium or such. every picocent counts :) | 20:02 |
| DocScrutinizer05 | http://www.wolframalpha.com/input/?i=copper+resistivity "~0.6 * resistivity of alu" | 20:13 |
| DocScrutinizer05 | "~0.3 to 0.8 x resistivity of alu alloy at room temp" | 20:15 |
| wpwrak | could work. make the wire a bit thinner too, and you're there :) | 20:21 |
| --- Sat Jul 7 2012 | 00:00 | |
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