It's the first thing you learn about TTL/CMOS chips: they cannot (should not) drive a LED directly. A transistor driver is needed, and is shown at the right in its simplest form.
When the gate output goes high the BJT saturates and current flows through your LED. A limiting resistor is needed to control the LED current.
The table below shows R values vs supply voltage vs LED current.
| Vcc | R ohm | R_ohm | R_ohm |
| 3,6 | 45 | 30 | 22,5 |
| 4,8 | 105 | 70 | 52,5 |
| 6 | 165 | 110 | 82,5 |
| 7,2 | 225 | 150 | 112,5 |
| 8,4 | 285 | 190 | 142,5 |
| 9,6 | 345 | 230 | 172,5 |
| 10,8 | 405 | 270 | 202,5 |
| 12 | 465 | 310 | 232,5 |
| 13,2 | 525 | 350 | 262,5 |
| I_LED [A] | 0,02 | 0,03 | 0,04 |
| V_LED [V] | 2 | 2 | 2 |
| V_CE [V] | 0,7 | 0,7 | 0,7 |
I will need these in my hi-brightness red LED optical MCW transmitter.
