polarity protection again! Sorry!

[njkmonty]

few questions..
assuming for 9vdc..

whats the recommended protection circuit?
whats the purpose of a low ohm resistor? ie the 10r? 1/2 watt rating
in the schematic with the zener diode, would you use a 9.1v or 10, 0r 12v?
also would this work for higher volatges? ie 12 or 15vdc, if so if using the bottom schematic, then use a zener diode slightly higher than supply voltage?
Am i understanding this correctly, could someone chip in for me?
sorry for the repated questions!

[R.G.]

whats the recommended protection circuit?

It depends on your objective. They protect against more or fewer possible situations.
There are a zillion pedals with only the reverse-polarity diode. This protects from short duration, low(ish) current reverses, like a reversed battery or current limited power adapter. It dies if you hook up a 9Vac power source.
The series Schottky diode protects against both the reversed battery and the AC adapter, but loses you a fraction of a volt from your power supply all the time.
The MOSFET protects against the reversed battery and the AC adapter, but loses you only 50-100mV from your power supply voltage. Costs more, though.

whats the purpose of a low ohm resistor? ie the 10r? 1/2 watt rating

Don't know. Maybe for some filtering when properly followed up by a BFC. Maybe for some current limiting when the pedal circuit dies shorted so you don't destroy your power adapter. Could be for several reasons.

in the schematic with the zener diode, would you use a 9.1v or 10, 0r 12v?

10V

also would this work for higher volatges? ie 12 or 15vdc, if so if using the bottom schematic, then use a zener diode slightly higher than supply voltage?

Yes. Yes.

[midwayfair]

whats the recommended protection circuit?

The one that does what you need with space on the layout and for what you're willing to spend. A 4001 is cheaper than a 5817 is cheaper than a PNP MOSFET. However, I personally think the first one sucks and shouldn't be used in any circuit powered by a DC adapter. It was made for battery-powered circuits. All it does with a DC adapter is kill a diode and let a manufacturer know that someone hooked up the wrong supply.

whats the purpose of a low ohm resistor? ie the 10r? 1/2 watt rating

It serves two functions: One is to form a high-pass filter with the filter caps, the other is to limit current to the entire circuit.

[/quote]in the schematic with the zener diode, would you use a 9.1v or 10, 0r 12v?[/quote]

What's the maximum supply voltage of your components? What's the supply voltage for your circuit? This is like asking "should I use a 100nF cap or 10nF cap in my circuit" -- there's no context to answer the question.

[njkmonty]

if you wanted to protect against low AC power supplies, ? or do you need a rectifier?/4 power diodes etc?
also is the zener to protect against "over", "excessive" voltage? if so could that be used inconjunction with a 1n5817 instead of using pnp mosfet>?

I Just noticed that a lot of madbean layouts etc used the 10r in front of power supply, and thought it may have  a purpose relating to protection  etc

[R.G.]

All of the series polarity protection schemes protect against AC adapters.