You have to connect the CA to +5, and NO, doing so will NOT "overvolt and damage them" - unless you don't use a resistor!
When the LED is ON it's its forward voltage is "3.5V"
So, the balance of the 5V will be across the resistor - 1.5V
That 1.5V across the resistor will determine the LED current
1.5V / 100? = 15mA
I spelled all of that out in Reply#37. You're not reading.