Multisim and Ultiboard

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Circuit help!


so i have and and or operation, I believe that circuits are connected properly but the LED will not light. Can someone please explain?

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Hi 01AndyK,



The LED is supposed to be ON in these conditions:


  • x and y are both at 5 V regardless of the state of z
  • z is at 5 V regardless of the states of x and y

To test if the LED is functional, set all switches to 5 V. If the LED remains off then you may need to check your simulation settings such as Digital simulation mode. For example the default mode is 3.3 V logic level. You may also want to lower the resistance in series with the LED (e.g., 200 Ω, 300 Ω).



Best regards,

G. Goodwin


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