# Exclusive Or Circuit in SimulIDE

I have been testing basic circuits in SimulIDE. I created a basic exclusive or circuit that works most of the time. There are two inputs.

When both inputs are off the bottom LED does not light up, that is correct.

When 1 of the 2 inputs are on, the bottom LED lights up, that is correct.

When both inputs are on, the bottom LED still lights up, even though an exclusive or circuit should only output ON when 1 of 2 inputs are on. In other words, if both inputs are on, the bottom LED should not light up.

I was wondering if timings could be the problem, but I'm not comfortable enough with circuits to trouble shoot this. Why does the bottom LED light up when both inputs are ON?

(Bottom LED should be off)

Bottom LED should be offI hope this is the right place to ask, and that the tags are correct. If they are not, please let me know.

Edit 1: So I began adding LEDs everywhere I can to test for an issue. Strangle adding an LED after the bottom OR fixes the issue. Adding an LED after the inverter also fixes the issue. The question now is, why is this happening?

(LED placed after bottom OR causes bottom right LED to turn off)

(LED placed after inverter also causes bottom right LED to turn off)

When I say "turn off" in the captions I'm referring to how that LED should behave in an exclusive or circuit.

• You have three LED's at the output of the LED. They are redundant. You might want to consider adding an LED at the output of the inverter. Remove the redundant LED. Also add an LED at the output of the second AND gate just like your original post. – Mahendra Gunawardena Aug 11 '20 at 2:37

After posting this question to the SimulIDE boards, I have found the answer. The LEDs internal property resistance had to be set to 100 for the circuit to function correctly. A user could also add resistors before the LED to achieve the same effect. This is the link to the SimuleIDE forum. My question was posted under Help and was titled "Exclusive OR Circuit behaving strangely".