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The big improvement is a current source! By charging a capacitor with a constant current, the voltage across it rises at a linear rate instead of exponentially. This makes your threshold voltages much more precise, since the time between each upper and lower threshold remains the same; whereas if it were exponential, it would approach Vcc at an increasingly faster rate, which means the difference between each voltage step becomes smaller and smaller... meaning your threshold circuits have to get much more accurate, increasing complexity, until you reach a limit where the difference between each step becomes too small to amplify! The LED's in this circuit represent threshold voltages, where each threshold is reached at a different time which reflects upon how long you have to hold the button for whatever action you wish it to execute; for Ex: 1s (turn on), 2s (program) ,3s (save), 10s (turn off)... etc. If you want a larger delay, just increase the value of the capacitor. Careful with the simulation, it may say "can not find solution" after a couple tries ;)
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