Here is a simple amplitude modulation patch: http://i.imgur.com/gsVDyw1.png

The idea is that when no amount is applied, no modulation can be heard, and as the amount is raised the modulation becomes more prominent, and when the amount is at the max the carrier's amplitude is being modulated all the way to zero amp.

But how do I do that? Here is a patch where there is a control for the amplitude of the modulator: http://i.imgur.com/DJIIfQs.png

The problem here is that, as we are multiplying both signals, the control also lowers and raises the amplitude of the carrier. So when the "amount" is zero, there is no signal. That "amount" control ends up modifying the amplitude of the carrier too. It's not so much of an amount control, and ends up being a volume control for the carrier too.

How can an amount control for amplitude modulation be implemented? At the lowest amount there is no modulation, and as the amount rises the modulation becomes more intense. Is there a way to do this?

I think you need to add back in the "remainder" of what's not being modulated. So, when your slider is at zero, you need to add {+ 1} before the [*~], lest you multiply by zero, and get zero.

Take a second output from your Hslider, run it into [swap 1], and those two outlets into the respective [-] inlets. That'll give you the difference between the AM amount and one - ie, when the slider's at 0, then you need the un-modulated amount to be 1, and vice-versa.

[*~ 0.5]    <- your old patch part
     |
     | [Hslider]   <- your old Hslider
     | /      \
    [*~]       [swap 1]
     |          |     |
     |          [-  ]     <- weird looking subtraction object
      \         /
          [+~]
           /
       [*~]      <- the final multiplication before the output

Dang. Ugly. Sorry, I don't know how to enter ASCII art in this new forum. That took me longer than doing the patch!