No, you use the Teensy's 3.3V at the optocoupler Vcc. The relay power supply JD-VCC is 5V. The opto isolator prevents that voltage from ever getting near the Teensy pins.
No, you use the Teensy's 3.3V at the optocoupler Vcc. The relay power supply JD-VCC is 5V. The opto isolator prevents that voltage from ever getting near the Teensy pins.