Diode Substitutions?

[mshuptar]

I have a couple general questions: when is it appropriate to substitute diodes? How would I know if a certain diode would work without significantly altering the sound?

I ask because I'm working on a Fatpants and I'd prefer to order everything from Mammoth, but they don't stock 1N5817 diodes.

[midwayfair]

In general, you want to use diodes with the same forward voltage when substituting. Datasheets for diodes can be hard to interpret, though, which does make it hard. Some suppliers will just tell you the Fv.

Any Schottky diode should be an okay sub for the 1n5817, including 1N60P, BAT41/43, etc.

Weird that Mammoth doesn't carry those, they're extremely common. Even Tayda has them.

As far as "significantly altering the sound" you have to determine what the diode is doing in the circuit.

In the Fatpants, the Schottky diodes are part of the charge pump and you can think of them as essentially directing the DC. Higher Fv will cause greater voltage loss. Ideally, you'd use the lowest possible forward voltage you can get out of a semiconductor, but I don't really know if there's anything that goes lower  on average than the .2V of the 1N581x series.

[mshuptar]

Thanks! I'm still learning about this stuff and I'm sort of "building-by-numbers." So, if I understand correctly, the diode is like a faucet on a sink; a lower Fv means that the voltage "flows" less restricted, right?

(Also, Mammoth carries 1n5818, so I ordered those.)   

[midwayfair]

Thanks! I'm still learning about this stuff and I'm sort of "building-by-numbers." So, if I understand correctly, the diode is like a faucet on a sink; a lower Fv means that the voltage "flows" less restricted, right?

That's an okay analogy, but better suited to resistance.

http://en.wikipedia.org/wiki/Diode#Semiconductor_diodes