simple LED circuit.. did i do this right?
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. :D
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 :D