100 k ohm ¼ watt 5% resistor R3,R4

100 k ohm linear taper pot, ½ watt Caltronics P-68 R5

150 ohm ¼ watt 5% resistor R6

820 ohm ¼ watt 5% resistor R7

0.1 uF 50 V (or higher) ceramic capacitor C1

22 uF 35 V (or higher) electrolytic capacitor C2

18 Volt Zener diodes (NTE5027A) D1,D2

Bulb: 6-12V @ 55mA or, 6.3V @ 0.075 A type ML612 or 7377 B1

Bicolor LED Red/Green RS# 276-012 LED1

Jack for electrode leads (3.5mm or 1/8″ mono-phone jack) J1

Jack for silver wire leads (2.5mm or 3/32″ mono-phone jack) J2

Espero que sirva de algo en el link esta el esquema bien claro.