Level shifting 5V  3.3V My main goal is to use connect the HC-SR04 ultrasonic sensor with ESP8266.

Problem is, HC-SR04 works with 5V while the ESP8266 works with 3.3V
In order to solve this, idea would be to use a logical level converter.

I bought some of this 3.3V 5V TTL Bi-directional Logic Level Converter(s) a good while ago, and thought they would fit best for this project.

Here's my setup


5V from arduino
3.3V from digital power supply
GND connected together
Nothing connected to TX0 (HV side)
Voltmeter connected to TX1 (LV side), still getting a 3.3V




Here's a closer look at the breadboard connections


Am I doing something wrong ? Any suggestions would be appreciated !
Edit: Forget the post above if you just want to know how your board is working. Your board is a retired Spurkfun product - clone.

Here you can see the schematics and all info about your board:

https://learn.sparkfun.com/tutorials/retired---using-the-logic-level-converter

Original post:

The module you got, use the BSS138 MOSFET.
The circuit is easy, and how @Majenko said, it has just 2 pullups:
See https://electronics.stackexchange.com/questions/367052/replace-bss138-with-ao3400a-in-level-shifter-circuit



But this board is really strange: what means TX0, TX1, RX0, RX1 on the same MOSFET? It is better if you can measure it to be sure how to connect the sensor to the TX.

But there is a better way to solve it: Since you just have 1 input to your ESP, why not use 2 resistors?
5V--- 1k --- 2k --- GND
And connect the ESP input between the 2 resistors? It is even faster, because the MOSFET need up to 20ns to change state.