Eventually after growing tired of peeking about my sump pit, I decided to create a monitor that would both determining the depth of the water in the sump pit and indicate which (if either) pump was running. My first challenge was to create the depth sensor.
I used a capped piece of PVC pipe with stainless steel bolts spaced every 2 inches. I then wired those from the inside of the pipe to a DB-9 connector.
Transistors amplify the signal from each sensor in the pipe. Those signals are then used to light LEDs on a monitoring panel.
I also built a current sensor by wrapping 12 gauge shielded wire around a 1/2 steel core (I cute the head of a lag bolt). Then, I attached a small hall effect device to the end of the core to sense a magnetic field. Each time a pump draws current through the coil, it produces a 60Hz magnetic field that is sensed by the hall effect device. That signal is then filtered using a filter capacitor and then used to light an LED. Here is a video of the prototype current sensor.
Here is a video of the finished monitor panel working. It is both monitoring the depth of the sump pit and also monitoring the pumps.
