What av cable works on an iPhone 4 iOS 6.1.3?

This is what you need if you have HDMI inputs on the TV

Digital AV HDMI To HDTV Cable Adapter For Apple iPad 2 iPhone 4 4S iPod Touch

Have a look here http://www.ebay.com.au/bhp/iphone-av

Yes, a digital av adapter is enough, you can try :

http://store.apple.com/us/product/MD098ZM/A/apple-digital-av-adapter

or

http://www.amazon.com/dp/B00A5IL84Y/

I bought HDMI adaptor for my iPhone 4S and can't get it to work is there something I need to do in the settings