Stupid freaking mosfets...
So i was tinkering with my 555 pwm timer this afternoon and earlier on this morning I had added another 555 timer in bistable mode and made a few adjustments to my resistor/capacitor network. So to check things out visually since I don't have a scope I simply unhooked my connection to the FET's gate leaving it floating while I hooked an LED up to the timer's output. When I got done I just pushed the reset button on the first timer and it killed the power to the second timer. But, the thing is the way I had my circuit wired up I still had power going to the source of the FET.
I never really gave it a second thought... no voltage to the gate = no power flowing thru the FET. So I go to hop in the shower and when I get out I smell something burning. Damn freaking FET had switched itself back on somehow or something and it was going into meltdown mode. It even melted a hole in my freaking breadboard!
Well I guess that should be a lesson learned, never leave the gate floating on a FET when the source is hooked to power, even a measly 9 volts 2.5 amp rated wall wart. I reckon it must have leaked a few microamps thru the gate part of the silicon turning that part into a capacitor, and when the voltage got high enough hello short circuit.
Oh well, there goes $5.60 for the breadboard and about another buck or so for the FET... live and learn I guess... I'm just grateful that it didn't start a fire.
I never really gave it a second thought... no voltage to the gate = no power flowing thru the FET. So I go to hop in the shower and when I get out I smell something burning. Damn freaking FET had switched itself back on somehow or something and it was going into meltdown mode. It even melted a hole in my freaking breadboard!
Well I guess that should be a lesson learned, never leave the gate floating on a FET when the source is hooked to power, even a measly 9 volts 2.5 amp rated wall wart. I reckon it must have leaked a few microamps thru the gate part of the silicon turning that part into a capacitor, and when the voltage got high enough hello short circuit.
Oh well, there goes $5.60 for the breadboard and about another buck or so for the FET... live and learn I guess... I'm just grateful that it didn't start a fire.
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