I recently made a circuit using the ttl 7400 NAND gate IC. The concept is simple. There are two 4 bit inputs going into the 7400 IC. The 7400 IC does a 4 bit NAND operation on these bits, and outputs them. The outputs are used to drive 4 LED's(each LED represents one bit). I made the circuit and it does nothing. The LED's are all off when all input bits are LOW. If I change the input bits nothing happens. Here is a chart to sumarize the behavior of the circuit I built:
As you can see, no matter what the input the outputs is always 0000.
Here is a diagram of the circuit:
Here is the data sheet of the 7400 IC(I'm not sure who manufactured the chip but it says 7400N on it): http://www.ti.com.cn/cn/lit/ds/symlink/sn74ls00.pdf
(The top left diagram on the data sheets first page is the 7400's pinout diagram)