555, 74HC00, 74HC191, 74HC4028
In this project, you're going to play a game of listening to four tones and hitting a randomly selected one. If you hit the tone, an LED lights. You can adjust the difficulty of the game with the control volume.
When you finish wiring, turn power ON. You can hear from the speaker four tones for a very short time, followed by a randomly selected tone that sounds over a preset period. Listen to the sounds from the speaker for a while. Maybe you've sensed four different tones.
The key S1 corresponds to the tone of the highest pitch, and S2, S3 and S4 each correspond to the next lower pitch. Now, start the game.
When a randomly selected tone is still sounding, press the key that corresponds to that tone (S4 if it is the lowest-pitch tone). If you hit it, LED 5 lights. You can rotate the control volume to change the duration of the tones.
U4 555 is an oscillator that determines the interval of the game. While the output of U4 stays H, the NAND multivibrator U1 oscillates and the quaternary counter U2 counts up.
When the output of U4 changes to L, U1 stops oscillation and the counter U2 also stops counting.
At this moment, the counter value is decoded by U3, and the resistor network connected to the outputs Q0 - Q3 of U3 determines the voltage to undergo D-A (digital-to-analog) conversion. This voltage determines the oscillating frequency of the VCO U6.
|Bill Of Materials For Sound quiz.DSN|
|3||R1, R11, R21||22k|
|5||R2, R5, R13, R17, R20||100k|
|6 Integrated Circuits|
|3||U1, U5, U6||74HC00|