In many of these layouts the polarity protection diode is a 1n5817. I am starting to run out of them but have more 1n4004s than I can ever use; are the 4004s useful to replace the 5817 as polarity protection diodes?
Follow up question, what parameters should I have looked up on the data sheets to answer my own question?
The other problem with the 1N400x diodes is that when it's series protection the voltage drop with them will be around 0.7V instead of maybe 0.4V with the 1N5817, so it takes more away from the supply. That is the main reason I used the 5817's in so many layouts.
If the protection is parallel then the voltage drop isn't an issue. But the downside is the diode will blow up if you reverse the polarity and take out your board
I found a good source for 1N5817s on eBay and picked some up recently. 1N5818s have a slightly higher voltage drop, but then if you miss the higher input voltage, you can just use one of those 9.6V Boss wall warts .