I have this circuit built on a b board in front of me alternately flashing two LEDs. With or without C1 (100nf ceram. cap.) it seems to work the same so why do they have included in the pdf of this circuit?
pdf: http://www.quasarelectronics.com/kit-files/electronic-kit/3138.pdf
pdf: http://www.quasarelectronics.com/kit-files/electronic-kit/3138.pdf