[time-nuts] measuring currents on USB powered devices

[Bob Albert]

 Bill, I have elected to do just that.  I ordered a few USB female connectors with tiny pcb and a male-to-male cable.  I will put a milliammeter in the dc line.  My total cost around two dollars and I use my own test equipment.
Bob
    On Wednesday, December 4, 2019, 05:01:20 PM PST, WB6BNQ <wb6bnq at cox.net> wrote:  
 
 Hi Jim,


Whatever you do DO NOT bother with the el cheapo USB measuring devices.  
I bought a couple and I got to tell you they are, at best, a very crude 
indicator.  The calibration SUCKS big time.


You would be better off using some USB breakout devices and use your own 
measurement system.


Bill....WB6BNQ


On 12/4/2019 8:56 AM, jimlux wrote:
> Any recommendations or brickbats for devices that measure the power 
> drawn by USB powered devices.  I've been using a modified cable that 
> breaks out the red wire to run to a meter, but it would be nice to 
> have something that has a ADC and some sort of interface (USB?) that 
> would make it possible to log the power draw.
>
> I've got a bunch of wireless Beagleboards with GPS receivers and 
> RTL-SDR pods (to do phased array measurements) and I'm trying to come 
> up with better power information.
>
> (the recent WiFi NTP low power discussion prompts this).
>
> What would be great is if there were some USB "thru" pod that measured 
> this and reported the data over a USB interface (recognizing all sorts 
> of isolation issues that are possible), so I could plug the USB power 
> "to" the beagle board and the USB power to the RTL-SDR, and log them 
> both.
>
>
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