hey guys i am using proteus 8 professional. i downloaded a schematic capture file from internet to build a circuit for a step motor and i saw this component that i'm having a hard time figuring out what it is. I didn't find anything about it on the website where i got it from. It looks like a 7411 but its marked as a 7408 yet the number on the pins don't make sense.

i realize i probably didn't give enough information. so if you need, just ask. thank you. Maybe one of you have seen this before??

 

Your correct the pin with a question mark is not part of the IC. The 7408 is a quadruple two input AND gate. The 7411 is a triple three input AND gate.

Without the rest of the schematic, it doesn't tell us a thing.

If the circuit really does need a three input, it can be use the 7411 for both a three and a two input. For the two input you would tie two of the input pins together to get a two input gate.

 

Or it is a compound of U8:A and another of the U8 AND gates.

If you are not fussed with propogation delays, feed ouput of U8:A into an input of U8:C and your question mark input is the other input of U8:C.

Without having the rest of the schematic to look at, seems possible that gates C and D of U8 were unused.