As the title states I need a PWM controller for a tec of around 80-100watts. I plan to use a dell Laptop AC adapter with 19.5v and 7.7 amps available for the power supply. The reason I need it small is because I plan to make some can coolers for my family for Christmas. You know like mini desk fridges. I don't want them to freeze the cans and I don't want them to be turning them on and off a lot. So, I need something that will keep the little fridge around 40 degrees F all the time and not use an excess of power doing it.

I have looked around and I have found several controllers that would do the job. The problem with them is that they are huge. I guess I'm gonna have to break out the soldering station for this one.

So far my ideas are:
555 timer based with a trim pot and a power transistor.
Pros. Cheap and easy
Cons. It wont add more power when you put a warm can in. That means it will take a long time to cool it off.

Two of the above for a high and low setting with a temp switch for switching duty.

Any ideas? If I use just a temp switch I'm afraid it will kill the module in short order.