nicksydney | wpwrak: yup.....seen them before it's old :) | 00:57 |
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nicksydney | but i like their form factor ...tiny weeny ;) | 00:57 |
nicksydney | they also have for AV https://store.gumstix.com/index.php/products/585/ | 00:58 |
whitequark | lol wtf. somehow I have a few leds on the slave side of this optocoupler, and they light up, despite there being no power source except the LPT port at the master side | 12:20 |
whitequark | http://localhost:4000/images/3020t/lpt-input.png | 12:21 |
whitequark | GNDIO/VCCIO are connected to an isolating DC-DC converter connected to the slave side power supply | 12:21 |
whitequark | and no, no capacitors are involved | 12:22 |
whitequark | can it be that uh... the photoelectric effect generates about 5mA of current inside an optocoupler? | 12:23 |
whitequark | that sounds slightly absurd | 12:24 |
whitequark | also the spurious voltage is 1.8V whereas the band gap in silicon is 1.2V so it's probably not that | 12:25 |
ysionneau | 14:21 < whitequark> http://localhost:4000/images/3020t/lpt-input.png < will be hard for us to browse this page :) | 12:57 |
whitequark | ow | 14:31 |
whitequark | http://lab.whitequark.org/images/3020t/lpt-input.png | 14:31 |
wpwrak | jut smake sure JP1.2 is high enough :) | 14:38 |
wpwrak | ah wait | 14:38 |
wpwrak | if your bird did things correctly, ground floats, right ? :) | 14:39 |
whitequark | um | 14:41 |
whitequark | bird? | 14:41 |
wpwrak | eagle | 14:41 |
whitequark | that's not my PCB, that's the vendor-provided one | 14:41 |
whitequark | traced | 14:41 |
wpwrak | so ground floats | 14:42 |
wpwrak | well, or at least you don'thavegalvanic separation | 14:43 |
whitequark | I think it should float, yes | 14:43 |
whitequark | it should be galvanically separated | 14:43 |
whitequark | I mean, otherwise, what is the point of having the optocouplers there? | 14:43 |
wpwrak | cargo cult ? :) | 14:43 |
whitequark | lol | 14:43 |
roh | whitequark: optocouplers combined with schmitt-triggers are used for spike surpression and overvoltage protection in cnc/automatisation devices | 16:54 |
roh | so they are not only galvanic separation ;) | 16:55 |
whitequark | hmm, makes sense | 17:22 |
whitequark | http://lab.whitequark.org/notes/2014-06-14/transistor-as-a-light-source/ | 18:13 |
whitequark | fun effect | 18:13 |
larsc | if you pump enough energy into it almost everything will become a light source ;) | 18:22 |
whitequark | well, here, it's a semiconductor effect | 18:22 |
whitequark | despite how it looks | 18:22 |
--- Sun Jun 15 2014 | 00:00 |
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