[PD] How to implement amount control to amplitude modulation?

[JC Pedroza]

I'm trying to implement amount control to amplitude modulation similar to the amount control of frequency modulation. The more amount, the more amplitude variation. The problem is that I can't figure out how to implement it correctly.

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?