I recently bought a lot of TTL components like 8-bit registers, bus transceivers, etc. to build an ALU and 2 registers. My issue is that when I build a register, the voltage drops to 4.2, sometimes even below 4V even though I put resistors in every output in series with the LEDs. I built 2 8-bit registers with bus transceivers using 74LS377N for registers and 74LS245N for bus transceivers. These two registers are built on different breadboards. And I connected the power to the bottom breadboard and wired the bottom breadboard to the other breadboard to provide power to it. The problem is that voltage drops significantly across these 2 breadboards.
Then I tore it all apart and individually tested the TTL components to see what's gonna happen. I powered up the breadboard and connected the two power lines on the sides. I put an 8-bit register and then only connected the power and the ground pins, leaving the rest disconnected. Then I saw the voltage drop below 4.5V from 5.1V. And I had like 6 of these registers so I tested them all. Some of them dropped to 4.9V and one of them didn't drop at all. But mostly they dropped below 4.5V. What am I missing? Or is there something I don't know about or I'm doing wrong? I'm kinda new to this so every bit of knowledge is appreciated :)
EDIT: Later, I went on to try this on other logic gates like 7400, 7408, etc., and saw that they behave like this too. Most of them drop the voltage, and a couple of them keeps it the same. I feel like it's about the logic gates I bought. But I have like tens of them.
EDIT: The alu I'm building is the one that Ben Eater built in his video, here is a screenshot.
I built the exact same circuit but the LEDs that are at the bottom, which are the ones that are farthest away from the power supply, barely get any current. And I have checked everything like 10 times over the past 2 weeks. AND YES I have connected everything as Ben Eater did, except he was using some LEDs with built-in resistors so therefore I added 220 ohm resistors in series with the LEDs. But besides that, everything is the same.