I didnt use any variable resistors like shown in the schematic. I used fixed resistors like from pin 2 to pin 7, I used a 10k ohm resistor; and for pin 7 to +12 volts, I used a 4.7k ohm resistor. For the capacitor, I used a 0.01 uf capacitor. For the transistor, I used a 2n6673 npn power transistor since I didn't have the requred one. The circuit still worked despite my improvisations.