2 1.5V LED flasher by 555 timer IC

1.5V led flasher schematic

1.5V LED flasher by 555 timer IC
Part list:
R1- 5 kilo-ohms
R2- 5 kilo-ohms
C1- 100uF electrolytic capacitor
C2- 100nF
C3- 220uF electrolytic capacitor
C4- 47uF electrolytic capacitor
D- schotky or germanium diode but ordinary diode will do (1N4001)
LED- low power red, yellow or green LED

This simple LED flasher is powered by a CMOS type 555 timer IC that performs as a voltage doubler circuit to power up an LED. This 555 timer is operated in astable mode producing an output of approximately 1Hz square wave.Initially, at first cycle, the output of the ic at pin3 is approximately equal to voltage source (1.5V) which is not enough to light the LED. In this first cycle, the capacitor is charged. The output voltage of the next cycle is equal to the voltage source (1.5V) plus the capacitor voltage (approx 1.5V). Thus the total voltage from source to pin 3 is approximately equal to 3V, enough to light the LED.

6V LED flasher schematic

This is a simple LED flasher uses  555 timer ic but unlike the flasher above, this circuit uses 6V rather than a 1.5V supply.Another difference is it uses an ordinary type of IC and not a cmos type.
the sample components are shown below using the 555 timer astable-mode formula

Frequency = 1.44/[C1(R1+2R2)]
duty cycle= (Thigh)(Frequency)
For
C=10uF
R1-1 kilo-ohms
R2-18 kilo-ohms
around 51% duty cycle is around 51% and frequency is 3.9Hz.
See 555 timer calculator to check this derived values.