Ad Sense and PTCs

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I have a blog but I haven't put any Adsense ads because my blog has PTC banners. I put up that blog so I could get referrals. Recently, one of my MyLot friends visited my blog and suggested that I put some Adsense ads. Isn't this a violation of the Adsense TOS? I've also seen blogs with PTCs and Adense ads. I just don't want to be banned by Adsense because I'm planning to put up another blog. Do you have blogs with PTC banners or links and Adsense ads?