I've been trying to learn how to use logic gates. I wanted to use logic gate to bump digital signal from 3.3V MCU to a 5V. I took a T74LS38D1 and mocked the solution using two switches connected to 3.3v and GND instead an actual MCU. I also connected a multimeter to check the voltage between GND and the output of the gate.
I was surprised to see that the voltage for both input set to low was something around 1.2 to 1.4V. It was supposed to be a high state so I expected close to 5V.
When I set both inputs to GND the voltage on gate output was around 0.15V which is what I expected.
Why is the voltage of high gate output so low? Am I missing something obvious?
- I also used a different NAND gate chip, SN74LS38N and same thing happened. So this hints that my understanding is wrong.
- I have grounded any unused input pins on NAND logic gate chip.