Need a quiz show buzzer system? Check this out!
A Quiz Show Buzzer was just built only with 74XX series device. A single 74LS373 Octal D-Type Flip Flop was used instead of several AND gates. Eight DATA INPUTs serve as quizzer’s user interface and the eight DATA OUTPUTs were connected to 8-input AND gate which provide the logic HIGH or LOW to GATE INPUT of 74LS373, the purpose of this is to disable all inputs after the first output became logic HIGH. The logic signal from DATA OUTPUTs can be use to drive a 7-segment display (for displaying quizzer’s number) and SSR (for indicator).
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I see he runs his logic at a nice standard 7.6 volts.
7.6 V DC is within the minimum Vin Voltage Input for 7805 IC Volatge Regulator.
Video Clips:
http://www.youtube.com/watch?v=dLLAbiFAkfo
http://www.youtube.com/watch?v=pLz06YLw26s
http://www.youtube.com/watch?v=HuNiF8N0s8A