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Forum: Hardware Chat Room
Thread: Raspberry Pi 4 8GB out! $75 (May 2020) |
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Thread Status: Active Total posts in this thread: 26
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poppinfresh99
Cruncher Joined: Feb 29, 2020 Post Count: 49 Status: Offline Project Badges: 
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Better option would be a dedicated power supply, like this. Is the idea to solder many jumper wires to a stranded wire for +V and solder many other jumper wires to a stranded wire for -V? The jumper wires then power the Pis via Pi's 5V and Ground pins? I guess also some jumper wires are needed for any fans too (or just connect them directly to the Pis). |
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hchc
Veteran Cruncher USA Joined: Aug 15, 2006 Post Count: 865 Status: Offline Project Badges: 
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One dedicated, high-efficiency power supply to power multiple SBCs seems simpler and less cluttered, but it's hard to find a good one, and it presents a single point of failure compared to each SBC having its own adapter (though the individual power adapters are much less efficient from what I've read, much lower than 80+ standard?). The Amazon reviews for the one linked indicate that it could be unreliable to deliver enough voltage, so I would personally keep looking for a better one.
----------------------------------------I also don't currently know how to hook up multiple cables to those leads, to be honest. Is it just solder? Just lather it on in a big blob? I'm a beginner to soldering and would have to buy a new iron (my iron from high school has long disappeared) and also find a quick how-to guide. The page for ODroid MC1 shows pictures of similar looking power supplies connected to many SBCs. I can't tell if the leads are soldered on or not.
[Edit 1 times, last edit by hchc at Jun 13, 2020 1:13:43 AM] |
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hchc
Veteran Cruncher USA Joined: Aug 15, 2006 Post Count: 865 Status: Offline Project Badges:
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poppinfresh99 said:
----------------------------------------Instead of an Ethernet switch, would WiFi have any real disadvantages? Interference? Losing connection? Power usage? I'm a technology perfectionist/purist and believe WiFi is really a last resort for connectivity and best for mobile (phone, tablet, sometimes laptop when not at a desk) and the occasional IoT device. But in my opinion a cluster of dedicated computers would ideally be connected via Ethernet, and for security reasons WiFi and Bluetooth modules disabled (and perhaps shave off some milliWatts of power haha). If I built a cluster of e.g. 4 of 7 Pis, I'd definitely prefer to buy a cheap Cisco or Netgear or ZyXel unmanaged switch, 1 foot Ethernet cables, and call it a day. To answer your question, more client devices ("supplicants") added to a WLAN (WiFi) network does affect overall network performance since it adds to utilization and is a source of noise. WiFi is a shared medium, and client devices are polite and tend to wait their turn to speak (with the exception of 802.11ac Wave 2 MU-MIMO and 802.11ax), so if the cluster of Pis or ODroids or whatever are on the same 2.4 GHz or 5 GHz channel as, say, your main laptops, phones, tablets, etc., it could potentially slow down throughput. I'm not a fan, personally. Perhaps one-off projects like weather stations, plant watering monitors, garage door openers, etc. can be WiFi, but not a cluster of SBCs. Edit: If WiFi is a must, it's probably better to set all the SBCs to use 2.4 GHz 802.11n instead of the 5 GHz band, which should be reserved for phone/tablet/laptop and devices that can handle the speed and 802.11ac modulation.
[Edit 1 times, last edit by hchc at Jun 13, 2020 3:59:48 AM] |
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poppinfresh99
Cruncher Joined: Feb 29, 2020 Post Count: 49 Status: Offline Project Badges:
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The page for ODroid MC1 shows pictures of similar looking power supplies connected to many SBCs. I can't tell if the leads are soldered on or not. That a great webpage. When powering 4 ODROIDs, seems that they use the same power supply as cwierzbicki's, but they use the following for powering 16 ODROIDs... https://www.amazon.com/dp/B07C58BLYY/ Looks like, for the DC plug cables (for the ODROID), they just twist together as many as 6 cables (when powering 5+5+6 ODROIDS). Actually, most jumper wires are stranded in the middle (I think), so you could do something similar with the Pi! No soldering needed! Though I was reading that some jumper wires are not meant for more than 1A... [Edit 2 times, last edit by poppinfresh99 at Jun 13, 2020 1:26:08 AM] |
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hchc
Veteran Cruncher USA Joined: Aug 15, 2006 Post Count: 865 Status: Offline Project Badges:
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With those cheapy power supplies with Do-It-Yourself leads out the back, I'm so paranoid about a connection being loose causing heat and arcing and eventually a house fire. Or an electrocution hazard (especially on the AC input wires being exposed) since it's all exposed. I wish there was a more standard PSU model built for SBC clusters that simply had all the leads professionally installed and only a bunch of USB-C connectors (or Micro USB) cables poking out. Preferably from well-known brands instead of these no-name brands.
----------------------------------------Lots of stuff to chew on.   Edit: Maybe we can use a regular computer ATX power supply and buy adapters? Something that would convert either molex or SATA power cable (or PCI-E?) +5V connector to a bunch of USB-C or Micro USB? I almost think that would be safer. Edit 2: I don't want to reinvent the wheel, so I'll search some other forums (like Raspberry Pi forums, Reddit, Odroid) for more cluster PSU ideas.
[Edit 2 times, last edit by hchc at Jun 13, 2020 4:11:43 AM] |
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poppinfresh99
Cruncher Joined: Feb 29, 2020 Post Count: 49 Status: Offline Project Badges:
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Regular-computer power supplies are expensive---partly because they split the power into many different voltages (perhaps robbing us of the needed 5V power for a Pi). Perhaps we are inventing a new type of wheel.
----------------------------------------I have never considered that there is any danger with 5V. For a 12V car battery (or even a 9V battery), you can get sparks if you short it (just for a moment by tapping!), but there is no arc or large heat. As for the wall voltage, I still don't think you could get an arc unless you had some material with electrical resistance (like graphite) to first heat up the air. The connection should be secured by the screws, so little risk of even any sparks. Certainly don't touch the metal of that connection because you might accidentally touch a non-ground wire, so I'd just use enough layers of electrical tape. Edit: Oh, I'd also make sure that there is plenty of electrical contact while I'm screwing in the wires for the wall voltage. Shoving current through a tiny area of contact would produce heat. [Edit 2 times, last edit by poppinfresh99 at Jun 13, 2020 2:20:18 PM] |
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