Hi,
You must check the datasheets & if the 1W type need (eventually) higher current for the stabilizing, change the right resistor for that, but possibly it will function with the old one too...
K.
Hi,
We multiply the full maximum current by the zener voltage since when no current is flowing through the load - e.g. when the device is switched off - all of the current will flow through the zener diode.
So, if we have a zener regulator with output 9v 100mA, at full load, all the current flows to the load, but at no load, the current through zener = 9 * .1 = 0.9W, here you need to use zener with power rating of atleast 1.3W.