Now that I’ve built your newer (2313) version and your older analog one (555+4017), I’d love to better understand why the transistors are helpful. The output from the 4017 pin is passed through a 47k resistor to the base of a 3904, which is also connected to a 47uF capacitor, together forming a low-pass filter, right? Assuming a 9V power supply, the resistor drops the current from the 4017 to about .2 milliamps, which the 3904 then boosts it back up by 100X to about 20milliamps for the LED, right? But doesn’t a low-pass filter work without the transistor too? That is, could the 47k resistor and 47uF capacitor be replaced with a 470 ohm resistor and 470nF capacitor and get the same effect? Or am I missing something?