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Re: IRF510 amplifier failures
One other possibility to consider to protect against overcurrent situations is to use a current limiting power supply, or add a current limiter to an existing power supply or battery.
The current limiter circuit whose link is at this site:
will go up to 2.2 amps, and includes a low-dropout voltage regulator that also provides reverse polarity protection.
There is a version, in a different package, of that same regulator chip that has an added "tracking" feature - being able to parallel multiple chips to increase the available current. Details are on the datasheet in the document.