Principally this both simple low voltage LED flasher circuit diagram are same, using voltage doubling principal with the additional of transistor to allow the capacitor to discharge faster and supply great current about 40mA peak. A large capacitor 1000uF in series with330 ohm resistor would increase the flash duration to about 50mS. The discrete 3 transistor at the right circuit would need a resistor (5K ohm) in series with 1uF capacitor to widen the pulse width.

source : bill bowden’s circuit collection
low-voltage-led-flasher-3