I have often stated that generic numbers do not tell the full story.
Charles states:
Using the 7406 ... It has an open collector NPN transistors which can tolerate up to 30 Volt thru a load hooked to them.
Somehow that answaer bothered me (I have not used 7406/7407 for a long time) so I picked a 7406 datasheet at random (this) and my faint recollection was right. Not all 7006/07 can handle 30V, some are only guaranteed for 12.

Let us try to give the whole number when we ask and when we answer.

Erik