On a sunny day (Sat, 2 Jan 2021 12:51:35 -0000 (UTC)) it happened Martin
Gregorie  wrote in :

>On Sat, 02 Jan 2021 12:34:29 +0000, Martin Gregorie wrote:
>
>> On Sat, 02 Jan 2021 09:49:46 +0000, Dave Liquorice wrote:
>>
>>> On Sat, 2 Jan 2021 00:52:59 -0000 (UTC), Martin Gregorie wrote:
>>>
>>>> I tend to keep a Pi power cable modified so I can measure the voltage
>>>> across it. I run the cable through a small plastic box with terminals
>>>> on the lid,
>>>
>>> Or get one of the in line USB voltage and current meters.
>>>
>> That makes sense - I didn't know these are available, but should have
>> guessed. The only disadvantage would seem to be that you'll end up with
>> a collection on different adapter cables since almost all of them seem
>> to have just USB-C connections.
>>
>>> I've a KEX KCX-017
>>>
>> Like so many Chinese things, Amazon currently has that one marked as
>> 'unavailable', don't know when we'll have more.
>>
>> Dunno why their manufacturers persist in doing that: in makes them look
>> like fly-by-night chancers, but maybe that's exactly what they are.
>
>Belated thought: I wonder how many of these nice toys, many of which
>which seem to have just one short production run, are actually final year
>projects for electronic design graduates at Chinese technical
>universities.

Most AFAIK (the stuff I bought) are just based on chip manufacturer application
notes.
If you look at the chip number and locate the data sheet with google you likely
find a circuit diagram :-)

To measure DC without breaking any wires I have a Voltcraft VC-330 (google) AC
/ DC clamp on meter.
Maybe slice an existing USB cable open, find the +5 V wire, clamp it on,
measure it, tape it closed (have not tried it on USB).
It is a useful universal thing that you can use for anything like for example
measuring stuff in your car or whatever, without disconnecting or cutting wires
etc.
I would not buy something specialized for just USB.

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