I was building a TTL nand gate circuit on a breadboard, trying to get it so that one LED lit up when the output was 1 and the other lit up when the output was 0. This caused some issues because sticking an LED between the second transistor and ground introduced unwanted resistance. This biased the current toward the output, which caused logic 1s when it should have been 0.
So, I rewired some things and tried a few different setups, and eventually got it so that when the output of the nand was (or should have been) 1, the correct LED lit up green. (They're both green LEDs.) However, when the output was (or should have been) 0, the other LED was green as expected, but the one that should have been off in this case lit up bright orange.
Any idea what this means? I'm guessing it's just getting too much current or something (I had power running straight into the base of the transistor, which is probably bad), but it would be nice to get a second opinion.
So, I rewired some things and tried a few different setups, and eventually got it so that when the output of the nand was (or should have been) 1, the correct LED lit up green. (They're both green LEDs.) However, when the output was (or should have been) 0, the other LED was green as expected, but the one that should have been off in this case lit up bright orange.
Any idea what this means? I'm guessing it's just getting too much current or something (I had power running straight into the base of the transistor, which is probably bad), but it would be nice to get a second opinion.