40 LED Bicycle Light using 555 timer circuits

This 555 timer circuits below is a flashing bicycle light powered with AA cells 6 volts, Two sets of 20 LEDs will alternately flash at approximately 4.7 cycles /s using RC values shown . Time intervals for  two lamps are about 107 milliseconds and 104 milliseconds, Two transistors are used to provide additional current beyond the 200 mA limit of the 555 timer, A single LED is placed in series with the base of the PNP transistor so that the lower 20 LED turn off when the 555 output goes high during T1 time interval, high output level of the 555 timer is 1.7v less than the supply voltage, Adding the LED increases the forward voltage required for the PNP transistor to about 2.7v so that the 1.7 volt difference from power supply to the output is insufficient to turn on the transistor.