Construction Directions

1. Drill 1/16" holes in paint stirrer as indicated on Front View.

2. Cut 2 pieces of 12-2 wire to length, one black and one white (see Back View figure). Strip about 1/2" of insulation from both ends. Tape both pieces to back of paint stirrer with electrical tape just below the LED holes. (See Back View)

3. Insert components from Front of stirrer. Watch polarity of Beeper and LED. Resistor is not polar. Flat side of LED is cathode (negative).

4. Solder connections per Back View figure. Polarity is EVERYTHING!!! Do not overheat LED. A heat sink may be prudent. Scrap some enamel from the copper NW wire with steel wool or sand paper to make it easier to solder.

5. Tape 9V battery in place with electrical tape. Connect 9V battery. Test probe in electrolyte solutions.

Adapted from Eliason, R., Galstad, S. "A Simple Conductivity Device", Chem 13 News, May 1992