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Factory Factory posted:Power and signal are entirely separate and there's no problem getting your +5V and +12V and +3.3V from entirely different sources, as long as you make sure nothing's cross-wired and about to release magic blue smoke. The only potential issue is if you're using a single-wire signal that relies on ground, but that's simple, because you can bridge the ground no problem between 5V and 12V. In fact, shared ground is probably the better idea. Cool, so I can just straight up bridge them? I don't need any sort of protective circuitry? I think my signal does rely on ground, I'm using this circuit below (except with the pi instead of a U421). Will I need a different resistor since I'd be working with 12v? 
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| # ? May 13, 2013 16:20 |
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| # ? May 18, 2013 21:54 |
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I don't think so, but my knowledge here is kinda derivative. Shared ground is extremely common in multi-rail PSU design and tends to alleviate a number of issues when working with multiple voltages. If you know that your two power sources will have wildly different ground states, then bridging might indeed cause problems, but that shouldn't be the case - for low voltages and currents like these, "near zero" will be pretty darn well near zero. Might be best to head to the electronics thread in CC -> DIY to ask.
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| # ? May 13, 2013 16:41 |
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ante posted:Yeah, but as mentioned, he just needs a photo interrupter switch. Like this:
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| # ? May 14, 2013 02:29 |
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Is there any way to reduce the CPU usage (not just changing nice level) of applications like SABNZBD+ and Samba Server without adversely affecting security (the usage presumably being a result of SSL)? Either of those applications is pretty much capable of maxing the CPU all on their own during a full-speed transfer. Also, Headphones has continuous high CPU utilization, on the order of 50%, regardless of whether I'm using it or not. Anything I can do to cut those down?
Paul MaudDib fucked around with this message at May 15, 2013 around 01:22 |
| # ? May 15, 2013 00:06 |
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I'm really sorry for asking this but I don't really want to read 38 pages to find the answer to this question (and again I'm sorry as it has probably been asked a lot of times) but... Could you please tell me good links for projects and stuff? I got the other day a Rpi and I'd like to start doing things with it and learn.
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| # ? May 16, 2013 20:25 |
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Billa posted:I'm really sorry for asking this but I don't really want to read 38 pages to find the answer to this question (and again I'm sorry as it has probably been asked a lot of times) but... W..what are you looking for exactly? I mean, that's a pretty generic request...
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| # ? May 16, 2013 21:31 |
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HATE TROLL TIM posted:W..what are you looking for exactly? I mean, that's a pretty generic request... That's more than enough, thanks man.
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| # ? May 17, 2013 07:40 |
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Does anyone know if it would be possible to hook 10 RPis together to create the world's smallest, goofiest, weakest supercomputer?
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| # ? May 18, 2013 06:30 |
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Yes http://www.southampton.ac.uk/mediac...rcomputer.shtml
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| # ? May 18, 2013 06:53 |
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Used one of these babies as a CA and RADIUS server for wireless EAP-TLS authentication. Had to teach myself Linux since I barely used it before. It was actually pretty painful to be honest, had trouble finding good documentation, and everything I found was incomplete or contained errors. Had a lot of problems where I'd get errors that in no way guided me to what the problem was. However, I struggled through it and it all worked out. I plan on using these more in the future, saved tons of money compared to any of the alternatives.
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| # ? May 18, 2013 07:33 |
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Excellent.
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| # ? May 18, 2013 13:58 |
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quote:The whole system cost under £2,500 (excluding switches) and has a total of 64 processors and 1Tb of memory (16Gb SD cards for each Raspberry Pi). Yes, flash memory is totally the same thing as SDRAM 
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| # ? May 18, 2013 15:42 |
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Paul MaudDib posted:Yes, flash memory is totally the same thing as SDRAM ... It never says that? Storage is colloquially called memory sometimes, you know? They are memory cards, after all.
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| # ? May 18, 2013 20:52 |
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| # ? May 18, 2013 21:54 |
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As its a supercomputer the flash memory may well be used as swap memory! I've never tried a swap that large, and the latency may be massive but given the guy made a cluster out of R-PI he's probably daft enough to try that too.
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| # ? May 18, 2013 21:06 |
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