材料BOM表：

C1 100nF 63V Polyester or Ceramic Capacitor
D1 Red LED (any type)
IC1 4017 Decade counter with 10 decoded outputs IC
P1 SPST Pushbutton
B1 3V Battery (two 1.5V AA or AAA cells in series etc.)
Sensing probe__3 to 15 cm. long, stiff insulated piece of wire