Quiz buzzer for two teams

Parts in this circuit

Wiring, pin by pin

Red = 5 V, orange = 3.3 V, black = GND, other colours = signals. “Pin” is the position on the 40-pin header; the GPIO number is what the code uses. Power the Pi from a 5.1 V supply and wire with the power off.

Python code (gpiozero)

from gpiozero import Button, LED, Buzzer
from time import sleep

p1 = Button(5)
p2 = Button(6)
reset = Button(13)
lamp1 = LED(17)
lamp2 = LED(27)
horn = Buzzer(22)

while True:
    lamp1.off()
    lamp2.off()
    print("Ready. Who is first?")
    while not (p1.is_pressed or p2.is_pressed):
        sleep(0.005)                           # check very often
    if p1.is_pressed:
        lamp1.on()
        print("Player 1 was first!")
    else:
        lamp2.on()
        print("Player 2 was first!")
    horn.beep(0.2, 0.1, n=2)
    reset.wait_for_press()
    reset.wait_for_release()

How the code works

• The while not (...) loop waits until at least one button is pressed.
• The first if decides the winner. After that the program stops reading the buttons, so the second player is locked out.
• The reset button sends the program back to the start of the outer loop.

Parts to buy

The links open a search on each store, so you see what is in stock today. Check the model, voltage and price before you order.