From: James Cameron <quozl@laptop.org>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Tue, 7 Apr 2020 20:56:54 -0700
Subject: Re: [EE] The Raspberry Pi Power Plug
Thread-Topic: [EE] The Raspberry Pi Power Plug
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Across the range, the same power socket is used, a MicroUSB.

Properly rated power supplies with a MicroUSB plug are so common that
it would be rare to splice the cable from an old one.  On the other
hand, a dead power supply with a MicroUSB plug would go into my USB
junk box after removing the power supply.  ;-)

You didn't say which model of Raspberry Pi you are using, but they
start at about 200 mA for the first one.

Some switching power supplies aren't happy with such a small current;
there will be a minimum current specification.

On Tue, Apr 07, 2020 at 10:20:55PM -0500, Martin McCormick wrote:
> After a several-year-old Raspberry Pi didn't come back up after a
> power failure, the problem turned out to be the 5-volt switching
> supply.
>=20
> 	Adafruit, the company that sells the Pi and supply
> matched the part number we supplied and I just got 2 new 2-amp
> 5-volt supplies today.
>=20
> 	The 2 Raspberry PI's I have both use what I believe to be
> a microusb plug for power only.
>=20
> 	The replacement supply is the correct supply but comes
> with a round coaxial-style power plug like one sees on a zillion
> and 1 gadgets these days.  There are lots of sizes and variations
> on the theme but the body of the plug is often-times negative
> ground and the center conductor is, in this case, +5 volts DC.
>=20
> 	Being the pack rat that I am, I did save the power cord
> off the dead supply so I cut the power cable from the new supply
> in half to save the molded coax connector.
>=20
> 	Stripping the bare wires shows a red and black just like
> the microusb plug so after splicing the old plug on to the new
> cable, the Pi rises high again.
>=20
> 	Do new Raspberry PI's use a different power plug these
> days or do they just figure people are smart enough to figure out
> they can save the day by saving the old cord and splicing it on to
> the new supply.
>=20
> 	In this case, more power means the components in the
> supply are probably not straining as hard and therefore are
> running cooler.
>=20
> Martin McCormick
> --=20
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--=20
James Cameron
http://quozl.netrek.org/
--=20
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