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I need a basic swtich driven by an audio signal

So I have to drive a coil with about 9 to 12 volts. I have a trigger signal which is basically a sine wave coming out of a cell phone's headphone jack, which I believe should be around 1/2 a volt.

 

The question is can't I just drive this with a Transistor used as a swtich with a diod attached to the latch pin to cut out the reverse voltage from 1/2 the sine wave to get pulsed DC at high Voltage?