V3 warms up even when computer is shut down

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Bouchu
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V3 warms up even when computer is shut down

Post by Bouchu » Mon Jun 04, 2018 6:22 pm

I just received my V3 dongle, and plugged it into a desktop computer I use for SDR reception.

I know the dongle gets hot when in use, but what is odd is that it also stays warm when the computer is shut down - the dongle never cools down to room temperature unless unplugged.

I have tested this several times by unplugging the dongle and allowing it to cool down and then re-plugging it into a USB 3.0 port while keeping the computer shut down. The dongle becomes noticeably warmer (although not as hot as when in use)! What could be the cause?

rtlsdrblog
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Re: V3 warms up even when computer is shut down

Post by rtlsdrblog » Mon Jun 04, 2018 11:50 pm

Do you happen to have a USB current meter handy?

Most SDR programs don't properly put the dongle into sleep mode after closing. But disconnecting and reconnecting it should put it into a low power mode where it draws about 100 mA.

Even at 100mA, if you're in a warm ambient environment the dongle could still get a little warm when not in use.

Bouchu
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Re: V3 warms up even when computer is shut down

Post by Bouchu » Wed Jun 06, 2018 1:43 pm

Thanks, I'll try unplugging and reinserting the dongle after shutting down SDR#.

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Airwind
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Re: V3 warms up even when computer is shut down

Post by Airwind » Wed Jun 06, 2018 9:10 pm

Wow. Those 100 mA seems a bit much for the low-power mode. I just tested mine with a USB power meter by only plugging it in without any software running, and it indeed drained about 120 mA of current (that's 600 mW). I wouldn't exactly call this low power.

EDIT: For comparison, the old classic rtl-sdr dongle from ebay draws about 100 mA while a Yardstick One from Great Scott Gadgets doesn't draw any noticeable current at all. A HackRF will draw about 150 mA in idle mode.

aurgathor
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Re: V3 warms up even when computer is shut down

Post by aurgathor » Thu Jun 07, 2018 2:54 am

USB ports should be off (no power to them) when the computer is shut down, so I find this a little (?!) strange, to say the least. If it plugged into a powered hub, the hub may still have power regardless of the PC, and if he PC is only sleeping, USB ports are usually powered. But I have yet to see a computer that has powered USB ports while it's truly off. (not they can't exist, but they most certainly not commonplace)

What computer do you have?

JEL
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Re: V3 warms up even when computer is shut down

Post by JEL » Thu Jun 07, 2018 11:30 pm

I believe it's pretty normal for USB's to keep power ON even when the PC is shut-down.

There's a setting in Windows and/or BIOS (You'd have to google for 'selective suspend' or 'USB power after shutdown', or something along those lines, to find more info on it than I know from memory) where you can switch it ON or OFF.

As far as I know it's so you can use USB-equipment to boot the PC automatically. And perhaps also so phones can charge over-night even the PC is not running.

The Airspy I have connected to Windows 10 gets warm even when the PC is shut-down.
Not as warm as when it's running, but definitely warm.

The USB mouse I use also, sometimes, keeps its LED light ON when the PC is shut-down (As with all things 'Windows' it's not always perfectly stable :) )

aurgathor
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Re: V3 warms up even when computer is shut down

Post by aurgathor » Fri Jun 08, 2018 3:33 am

Methinks it's definitely not normal, and I just tested 4 PCs and none of them have USB power when they are shut down.

I guess that could be a new feature I was not aware of. Another possibility is that the shutdown state was only hibernate, not a true shutdown which may very well be the case with Win 10.

What PC do you have that keeps USB power on?

JEL
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Re: V3 warms up even when computer is shut down

Post by JEL » Mon Jun 11, 2018 3:14 am

aurgathor wrote:
Fri Jun 08, 2018 3:33 am
What PC do you have that keeps USB power on?
Assuming the Q is for me; I have a windows10 ASUS.

I do believe windows10 does indeed use some kind of 'always on' (Under the hood, so to speak) in order to be able to boot fast.

But in the windows settings I noticed that USB are always ON.
I never changed the setting, since I haven't had any bad side-effects from it.

Destinea1
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Re: V3 warms up even when computer is shut down

Post by Destinea1 » Tue Jun 19, 2018 3:21 pm

USB power has always been default to be off when the computer is shut down.

I've never encountered a computer so far that has them on. What's the model of your PC/Laptop?
Last edited by Destinea1 on Wed Aug 08, 2018 5:37 am, edited 2 times in total.

JEL
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Re: V3 warms up even when computer is shut down

Post by JEL » Wed Jun 20, 2018 10:15 am

Destinea1 wrote:
Tue Jun 19, 2018 3:21 pm
USB power has always been default to be off when the computer is shut down.

I've never encountered a computer so far that has them on. What's the model of your PC/Laptop?
Assuming this was for me.

I use a so-called 'gamer-pc' set to 'high performance'.
Maybe that's what keeps USB active.
I don't know what computers generally default to.

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