If I am using a piezo siren as a load, and it consumes 120mA, and I use it as a common emitter with a 1K base resistor, How do I determine the wattage for the transistor? I\(_{}b\)(12mA) + I\(_{}c\)(120mA) X V (12V) = Watts? = 1.3 watts? It doesn't seem like it should be that easy...