“TRY IT OUT: CHANGE THE LIGHT’S SPEED To change the speed and difficulty of the game, play around with different values for R1, R2, and C1 around the 555 timer. Smaller values will make the game go faster. Larger values will make the game go slower. Flip to “How to Set the Output Speed of the 555 Timer” on page 166 for the calculations to figure out specific resistor and capacitor values based on the frequency you want. Note that R1 should not be less than 1 kΩ, as lower values might damage the 555 timer. But what if you want to change the difficulty on the go? Just replace resistor R2 with a potentiometer. Then you can change that resistance value by rotating the potentiometer shaft, which changes the speed!”