On Thu, 2 Jan 2020 09:45:30 +0000, Andy Burns
wrote:


wrote:

Looking for a replacement DC barrel plug to fit a BT Homehub 5A power
supply. I believe the plug is a "Type B 6mm 2.1mm"

Measuring the external and internal diameter of my original BT HH5a
plug, it's 5.5mm x 3 mm (not sure if the internal part of the barrel is
actually a cone shape, as the central pin on the socket is less than
3mm, though difficult to actually measure.

I thought they (internally) were cylindrical but with some sort of
sprung element to help make a good contact? That could be a single
spring 'finger' or a split inward sprung tube or a 'fork' (inside the
tip connector)?

The thought being that if both inner and outer part of the plug /
socket assembly were accurately machined / made and had at best a
light sliding fit on both parts (outer plug barrel in socket, pin
inside plug sleeve), the chances are a little bit of wear would mean a
tiny gap between the pin and plug sleeve and hence no contact?

I know the chassis sockets often have a spring loaded contact
(/switch) on one side and I guess that could make contact with the
plug barrel whilst pushing the sleeve onto the pin, but what about
in-line sockets?

Cheers, T i m


https://en.wikipedia.org/wiki/Coaxial_power_connector