/diy/ - Do It Yourself

>>1694991
Well there are LED driver ICs. Also some ICs that your circuit might already be using or that you could easily swap to may have their own current-limiting or collector resistor, I'm pretty sure 74LS logic ICs have ~100Ω from collector to Vcc (picrel), possibly with a diode drop or two in there to drop a little more voltage in case you have a 2V red LED. In any case I always see Ben Eater chucking LEDs on his ICs without any resistors and they seem to last a while, even if they do have more than 20mA through them.