Entry 003: Building the Meter

Since the prototype was a huge success, I got to have some fun burning myself with the soldering iron.

I drilled all the holes in the enclosure for the LEDs, jacks and a switch. I cooked up the circuit on a prototyping board. It may look a little messy to some, but it looks great to me. I tested the circuit by connecting one end of a serial cable to the DE9 connector and dunking the other end in a glass of water. It appeared to work as desired.

The frustrating (and time consuming) part was next. I had to build a probe that would stick into the cistern and tell the circuit which LEDs to light up. This is the fruit of my labors. 

The probe is a nine foot piece of plastic electrical conduit we had lying around. I drilled nine holes evenly spaced along the conduit. The tricky part was fishing each of the nine wires through the holes. One wire was pulled through each hole and held in place with a zip tie. Once I had all the wires through the right holes (it seriously took way longer than you realize), I cut off, stripped and tinned each wire. I assume you understand how this works. (For those that don't...the wire at the bottom of the probe carries the voltage. The water connects more wires to that bottom wire as the cistern fills. Comprende?)

The hook is made out of sheet metal and holds the probe to the side of the pump casing. What a clever use of a hose clamp eh?

I trimmed the prototyping board so it would fit into the enclosure.

How did Logan get all those LEDs lined up perfectly? He used a milling machine to drill the holes of course! (It is undoubtable that I would have gotten an LED off to one side if I didn't.)

I think the finished meter looks pretty clean. It should complement our utility panel nicely.