Is this possible?

[mhtplsh]

http://www.geofex.com/Article_Folders/ampprot/dcprot.htm

Here they hv suggested to use mosfet in place of relay. Now there r three pictures of circuits.
I want to use mosfet configration from circuit 1 with mosfet driver circuit from circuit 3. but i want to use single power supply.
Most interesting part i want is : i want to use this as speaker protector. Hence first the mosfet will conduct full.
then as the driving circuit voltage increases the current through the mosfet switch must reduce. So during overload
mosfet will work like bulb protector i.e. it will conduct less.
Is this possible?
If yes, then guide me how to do this?

 

[ilimzn]

I am not sure you fully understood the article. It is not possible to use circuit 1 with the driver from circuit 3, as the centerpiece of circuit 1 is the photovoltaic driver chip, which dispenses with the need for a separate floating supply. In other words, if you want to use circuit 1, you must either use it as it is, or have a floating power supply to charge the MOSFET gates.
Even so, i would not use circuit 1. Regardless what the article says, MOSFETs are not he most linear of 'resistors' even when fully saturated. Instead, i would use circuit 2 and interrupt the power supply in case of a fault.