Ztx869 1.5v LED flasher vs generic transistor

This is my 1.5 volt Led flasher that uses the ztx869 transistor compared to a generic bc547c transistor in its place. The ztx869 is harder to get and more expensive. I got mine at digikey. This circuit uses very little current. LEDs require 1.7 volts to light and this circuit run down to 1 volts. Show to light the LED a pump up capacitor. The capacitor charges when the LED is off then it adds the voltage to the battery when it's on making it a voltage doubler. Here is the link to the circuit and description: http://pigeonsnest.co.uk/stuff/picpro...