Wednesday, November 25, 2015

Simple FET Driven Strobe Light

 
We needed a strobe light around the house for some mechanical troubleshooting.  Most 'normal' people would just purchase one, but what's the fun in that.
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Our solution was to use a 555 timer chip to drive a MOSFET to drive a 12VDC LED spotlight.  The internet is filed with 555 timer chip examples so we will skip that discussion.  The problem is that a 555 is fine for blinking a standard small LED, but a small LED doesn't put out enough light to be used as a strobe.
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The simple schematic below shows how a MOSFET can be used as a simple switch that turns power ON/OFF to the 12VDC strobe LED to match the smaller signal generated by the 555 timer chip.  The nice thing about using a MOSFET as a switch is, being a voltage controlled device, it can work without biasing components (YMMV).
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Wire the MOSFET up with some JST connectors for convenience and you get:
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I know this isn't exactly "high tech", but the rig works fine.  Below is a short video of it "stopping" a ceiling fan from a distance of about 10 feet:
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