If the prototype of your electronic coin-toss circuit doesn't work, there are a number of troubleshooting steps you can take to find out why and correct the problem. Here are some helpful troubleshooting tips:

  • Examine all the component leads to make sure none of them are touching each other. If any of the leads are touching, gently adjust them so that they're not touching.

  • Make sure the circuit is getting power. Use your multimeter to test the battery voltage and verify that the leads from the battery snap connector are inserted properly into the solderless breadboard.

  • Carefully double-check your wiring to make sure that every jumper and every component has been inserted in the correct spot.

  • Verify the orientation of the 555 timer IC, making sure that pin 1 is in hole E14 and pin 8 is in hole F14.

  • Verify that the LEDs are inserted in the correct direction. For the red LED, the short lead (the cathode) goes in D21, and the long lead (the anode) goes in D19. For the green LED, the short lead (the cathode) goes in G21, and the long lead (the anode) goes in G19.