There are actually a lot of conventions out there which are for the tech industry, but most of the time these are only there for those in the tech industry. For a lot of tech fans (not industry insiders), going to one of these is probably going to result in a large amount of boredom and, unless they have a degree in engineering, a lack of understanding. They would probably be better served waiting for the highlights from the event.
Even though most of these conventions aren’t really there for the average gadget enthusiast, there are a minority which cater to these people as well. Often times these are also the events which contain the most popular types of gadgets and technology too, such as conventions for newly developed apps (app planet exhibition at the Mobile World Congress in Barcelona), so for most people these are really the only ones worth going to. By researching online, you should be able to find some tech conventions which suit your fancy pretty quickly.