This was a simple exercise in Nand technology. I used 2 Nand gate chips to control the function of 3 LED's.
2 Switches are installed on the homes front and rear doors. A lit Green LED indicates that both doors are closed. A Red LED indicates that the front door is open, while a Yellow LED indicates that the rear door is open.
I built a voltage regulating circuit to maintain proper voltage for the Nand gate IC's. Transistors are then used to turn on and off the LED's as not to burn out the IC's. Test switches have been placed in parallel with the door switches to check for proper operation of the circuit, as well as any faults in the lines going to the switches on the doors.