I bought the LS7220 IC which is designed to check passcodes.
For some reason, the pin 8 Lock Status Output does not illuminate the LED when I connect the power, and when I bridge the VCC in sequence pin 3, 4, 5, 6. I have not yet attached anything to the other pins, I just wanted to get this basic functionality to work first.
Hopefully I am not shorting the IC by connecting the battery straight to the IC, or forgetting to include a pulldown or pullup resistor somewhere? It is likely something basic, perhaps it does not output enough power to illuminate an LED?