Background: As part of a little project I'm looking to add a diode to a hair dryer to cut the output in half. This is the circuit:
The potential diode in question is at the bottom, and the simulated current through it is in the center graph: 2.184 A peak (edit: 3.1 A). By my math that would mean right about 0.7 A average (edit: 0.99). Technically, this would fall below the 1.0 A spec for average rectified output current of a 1N4004 diode. However this sheet by Vishay states
IFAV decreases with an increasing value of the reverse voltage during the interval of no current flow.
In my case the reverse voltage is 120V sinusoidal; potentially 240V if used in another country. Unfortunately the 1N4004 datasheet doesn't seem to indicate the reverse voltage for the IFAV spec.
So for my education, ultimately my questions are:
1) Practically, should a 1N4004 diode be able to handle 0.7A (0.99) IFAV with 120-240V reverse voltage for an indefinite amount of time? Or is that too close to the spec, and reducing life of the part? More generally, how close is too close to the IFAV spec?
2) If practically possible, would best practice be to use the 1N4004, or a 1N5404 (3A IFAV)? A 1N5404 would be harder for me to fit but is probably doable.