Next I replaced the 74HC00 with the 74HC08 chip, which is the AND chip. This chip functions opposite to the NAND chip. So only when I push the two tactile switches simultaneously the LED lights up.
In the last part of this experiment a diode is introduced. It connects the output of the first AND gate with an input of the same gate (figure 4-79 of the book). There is only one tactile switch left since the first pin is connected directly to the positive voltage. Once the tactile switch is pushed the LED lights up and stays on even if the switch is let go (like a latch).
|Overview of experiment 19 with the LM7805 on the right.|
|With 74HC00 NAND chip.|
|Latch configuration with pin 1 connected to positive voltage and a diode connects pin 3 to pin 2.|