- 4011 quad NAND gate (Radio Shack catalog # 276-2411)
- 4001 quad NOR gate (Radio Shack catalog # 276-2401)
- Eight-position DIP switch (Radio Shack catalog # 275-1301)
- Ten-segment bargraph LED (Radio Shack catalog # 276-081)
- One 6 volt battery
- Three 10 kΩ resistors
- Two 470 Ω resistors
The reason for this is contact bounce: the effect of a mechanical switch rapidly making-and-breaking when its contacts are first closed, due to the elastic collision of the metal contact pads.
Instead of the Clock switch producing a single, clean low-to-high signal transition when closed, there will most likely be several low-high-low “cycles” as the contact pads “bounce” upon off-to-on actuation.
The first high-to-low transition caused by bouncing will trigger the pulse detector circuit, enabling the S-R latch for that moment in time, making it responsive to the Set and Reset inputs.
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