Typical continuity check / ignition circuit?

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iter

HPR Glider Driver
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I'm looking for a basic circuit that can report continuity of an ignitor to a uC and fire it on command from uC--the kind of circuit you might find on an altimeter.

I expect it would have a FET (I wonder what kind) and a series resistor to limit current through ignitor during continuity check, but after that I need help.

Ari.
 
Ari, you don't need a FET, a simple resistor will do the job, in the sketch here I use a 2.2k but a 1K can do, it's just that I use my system to also ground test charge and electrical match are more sensitive , with a 1k the led will be more bright , Sorry for the bad writting, I injure my right hand yesterday , I did this one with my left hand , please take note the LED is reverse, lol it goes in the other side



igniter_zpsfc084cad.jpg
 
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Jerry, I wish you a speedy recovery with your injury. The miror-image LED is hilarious! What I'm looking for is a circuit I can drive from a microcontroller rather than by hand and eye.

Guy--thank you, this looks exactly like what I'm after. I wonder if there's a particular N-channel FET you recommend--they all look the same to me, yet I'm sure some are unable to handle the current while others are more expensive then necessary :=)

Ari.
 
I use the IRL2703 for high current circuits (24A), it runs about 1.00 each. For lower current I use the IRF8313 (8A), it is a dual FET package and runs about 0.50 each. Another good one I use is the IRFZ44 (57A), it is also about 1.00 each but for the higher currents requires a heatsink.
 
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