“Computing, communications, gadgets et al” is too broad of a category. You will get more luck the better you can narrow down your area of interest.
For example:

Photography: photo.net/community/
Digital photography: www.dpreview.com/forums
Nikon cameras forum: www.nikonians.org/forum_lobby

What communications are you interested in? Shortwave radio or mobile phones? Android or iOS?

What computing do you have in mind? Computer programming? IT? Building your own PC?

Gadgets making or gadgets using?

See what I mean?