Question about 74LS07

[nickagian1]

Hi all!

I am confused a little bit with something related with the IC 74LS07.

This IC has buffers, isn`t that correct? So let`s choose the first gate and apply +5V at the input (1A). I expect to get +5V at the output of the gate (1Y), right? So why is that not working with my chips? ??? (I have already checked two of them).

I cannot understand what is my mistake...

 

[audioguru2]

The datasheet and description of it says, "open collector outputs". Its outputs are transistors to ground. A load or a resistor between the output and a positive voltage is supposed to pull the output voltage high.

 

[nickagian1]

I guess you are right... I have a problem with one circuit containing the `07 and thought it was burned...so I checked it seperately and found this behaviour strange. But you are right with that open collector. Thank you!