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A : no</div>
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B : Best. They are out there but hard to find</div>
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C : no - likely to drive power back into the Pi and blow the fused resistor or whatever they use</div>
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D : works as well<br>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Synth-diy <synth-diy-bounces@synth-diy.org> on behalf of Rutger Vlek via Synth-diy <synth-diy@synth-diy.org><br>
<b>Sent:</b> 08 November 2022 19:28<br>
<b>To:</b> SDIY List <synth-diy@synth-diy.org><br>
<b>Subject:</b> [sdiy] USB power (slightly off-topic)</font>
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<div dir="ltr">Dear list,
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<div>I hope you don't mind me tapping into our collective list wisdom for something slightly non-synth related. The case is as follows:</div>
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</div>
<div>I'm building a NAS at home from a Raspberry Pi 4B and a couple of SSDs. The SSDs are connected to the Pi via a SATA-to-USB converter. They work, but stop working when used intensively. Not to my surprise, because the power requirement of the drive is 1.7A
at 5V each. The Pi USB ports can only deliver 1.2A at most (and shared between 2 ports). So I need a more beefy supply. My initial idea was to buy a couple of these USB Y-cables that have two USB-A connectors on one side, allowing the user to provide the paralleled
power of two USB ports. However, even on a single port, the Pi already reaches it's limits. So I thought, why not plug the second USB-A plug of the Y-cable into a USB-charge, so that it can provide all the current needed by the drives. However, I have a bad
feeling about this...</div>
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<div>I don't have a clue about the internals of a typical USB Y-cable, and have not been able to find any datasheets on them. In the worst case, power from the Pi's USB port would just be connected directly to the power output of the USB-charger, and that does
not sound like a good idea. They might not be at the exact same voltage, and I since both of them are SMPS's, I don't know if they'll somehow start interfering with each other. If only there would be some series diodes internally present in the Y-cable, but
I have no clue if there are... Does anyone know (or can measure)?</div>
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<div>Plan B was to buy a powered USB hub, but I struggle to find one that can deliver the required 1.7A at 5V on multiple of its ports at the same time.</div>
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<div>Plan C, that just came to mind, is that I might be able to find a beefy USB PSU with multiple ports, that I can use to feed the Pi from, as well as the drives via Y-cable. The Y-cable would then be combining the power from Pi's USB output with the direct
output of the same PSU. Would that work?</div>
<div><br>
</div>
<div>Plan D would be to make my own power distribution board, where USB connectors pass data between the Pi and the disks (but no power), and power is injected from a DC barrel plug (and some filtering)</div>
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<div>What do you think would be the best approach?</div>
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<div>Rutger</div>
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