At work my image setter (large machine that laser prints on photographic film) dumps it's waste chemestry into 2 35 gallon drums that are covered by a large wooden box (mostly for asthetics).
It's a pain in the butt to check them all the time so I rigged up a very simple circuit to light off an LED when the level gets to a certain height.
I just want to make sure that this is going to be safe and everything before I leave it setup unattended (I've tested it.. left it to sit.. nothing got hot or anythng so i'm figuring it will be ok for now)
i have a 9v battery with the negative lead going into the drum and cut.. then another lead going from the LED into the drum and the two are taped at either ends of a 1" piece of plastic. on the + pole of the LED a 100 ohm resister before heading back to the battery.
Obviously the battery is going to run dead if I leave it in when the barrel is full, but my boss didn't feel safe about using a ac-dc power supply. He figures if we have to replace the battery everytime, it's not his money anyway.
So does this all seem safe enough? I'm pretty stupid when it comes to simple circuits.. which is funny because I spent two years teaching a physics lab at a local upscale high school and this is one of the topics I actually have taught ^^;;
Anyway... someone who knows what they are talking about, please respond
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