Conecting your site

I have been using a niche about a product, i am now thinking of adding more sites in the same niche but similar products.

as a example i have a site about philips x10 tv then i want to create a site about philips z50 tv is it good to link this sites to each other, like a blog network?

I am using adsense on the sites so google would know who it its anyway

Depends on how you want to drive traffic to them really. If your doing white hat, then its no problem at all, since its a relevant link thats adding value to your users experience. If its black hat methods your testing, then its a total no go if you want to keep them both ranking.

Another option would be to develop an authority site and just keep adding content.