Game Plan Star Trip: Interfacing with the lights

LDR-1 (Light Driver) Next up is the LDR as if I lock on one of the lights it won't burn up like a coil. The process of driving the LDR is very similar to driving the SDR so I should be able to take my learnings onto driving the SDR in the future. The LDR has three 74HC4514 ICs. These ICs have 4 input pins which can configure one of 16 outputs to be active, giving a maximum light count of 48. The Star Trip pinball machine has less than this so some outputs are not connected. The IC also has an enable pin which when set to HIGH will disable all the output pins. The original MCU had the 4 input and 3 enable pins connected via J2. By pushing all three enable pins HIGH the LDR will disable all the lights. The idea of the LDR is you set the 4 pin input to an individual light number, enable the correct 74HC4514 chips enable pin (corresponding to the light you want to light). If you want to turn on multiple lights at once you actually turn on and off each individual light re...