Make the Gadget
To make this device, we’ll start by constructing the probe that you’ll dip into water samples to get a conductivity reading—which we created by repurposing a binding post (Radio Shack catalog #274-718) typically used in home audio/video and ham radio electronics. It may seem like a complicated build on first glance, because there are several steps involved. But it’s mostly a straightforward matter of connecting wires to the binding post—as you can see in the photo of the finished probe.
- 10K resistor
- 8-ohm speaker
- 4Char display
- Chassis-mount dual female binding post (RadioShack catalog #274-718)
- Jumper wires in various colors
- Several feet of insulated solid core wire
- Small piece of aluminum ...