Mole hitting game
Electronic
555, 74HC00, 74HC191, 74HC4028

In this project, you're going to make a circuit for a game of hitting moles popping up their holes. Four LEDs play the roles of moles, and one of them light at random (a mole pops up the hole). When an LED lights, you press the key corresponding to the LED. If you did it right, you made a hit, which is indicated by a beep.

You can enjoy competing with your friends for quickness.

When you finish wiring, turn power ON. One of LEDs 1 -4 randomly light for a short time. Press the key, S1 - S4, that corresponds to the LED while it is still lit. For example, if LED 2 has lit, press S2. If you pressed the right key, the buzzer sounds. U1 is a NAND multivibrator that determines the lighting cycle of LEDs, and U5 is an oscillator.

While the output of U1 is H, the pulses from U5 go into the counter U3 which counts them up.

When the output of U1 changes to L, the pulsation is disabled and U3 stops counting. At this moment, the value in the counter U3 is decoded to turn ON one of the LEDs 1 - 4. If the key corresponding to the lighting LED is pressed, the oscillating output of the NAND multivibrator U1 is emitted from the speaker.

Q5 serves to disable the LEDs from lighting during the counting.