开云体育

Probably just the incredibly thin wires and connector contacts in the micro-USB cable/plug/socket causing voltage drop at the Pi's high current draw, because I see the same "low voltage" problem with 120Vac powered Pi power supplies. I have one of the NW Digital Radio DRAWS hats, and I would never power a Pi using that hat from the micro-USB connector, especially since the DRAWS hat provides a 12->5 voltage regulator that backfeeds the Pi with much less voltage drop through the GPIO pins (i.e., the same power input connection that KG7KMV is using).

I just checked the NFPA's wire ampacity versus gauge table, and 22 gauge wire (which is larger than the wires in USB cables) is only rated for 0.92 amperes for power transmission. In other words, USB cables are vastly undersized for iPhone or Pi level power draws (and they get away with cheating only because the cable runs are short, unlike the 50 to 100-foot runs for house wiring). The voltage drop has to be relatively huge. There's a reason why, up until Apple, USB was rated for a maximum draw of 500mA.

Andrew, KA2DDO
author of YAAC

________________________________________
From: [email protected] <[email protected]> on behalf of Christopher Rose <kb8uih88@...>
Sent: Friday, December 11, 2020 4:01 PM
To: '[email protected]'
Subject: Re: [yaac-users] Success story

Does it need more amperage than it is getting?
Items plugged into the pi or stacked on it need power



-----------------------------------------

From: "Michael WA7SKG"
To: [email protected]
Cc:
Sent: Friday December 11 2020 3:46:53PM
Subject: Re: [yaac-users] Success story

I tried using the USBBuddy from Powerwerx with an RPi 3B+ and it always
gave a low voltage indication. It was fine for a few other things that
were USB powered, but was less than stellar for RPi use.

YMMV

Michael WA7SKG

Nate Bargmann wrote on 12/11/20 10:22 AM:

* On 2020 10 Dec 14:15 -0600, Tommy Beene - KD4CHW wrote:

Nice setup! Where did you get the 12v to 5v converter for the Pi? I
need one for a Pi in my truck to run mine and a high power DSTAR
repeater.

Another option I saw referenced elsewhere is the USBbuddy from
Powerwerx:

/> >
it looks like a USB A to USB C cable would be required for powering a Pi
4 or a USB micro for a Pi 3 and earlier.

I don't have one and there may be other similar devices available.

73, Nate

<<br>