Description
This 4 Channel Bi-Directional Logic Level Converter features high speed bi-directional 4 channels, allowing for safe and easy communication between devices operating at different logic levels.
The logic level converter circuit converts the low-voltage signal to a high voltage signal from as low as 1.8V to as high as 5V and vice versa, and its four channels are enough to support the most common bidirectional and unidirectional digital interfaces, including I²C, SPI, and asynchronous TTL serial.
This four-channel bi-directional level converter is a tiny device that safely levels down 5V signals to 3.3V and also it can steps up 3.3V to 5V. This level converter is also compatible with devices that operate at 2.8V and 1.8V.
So, Now you can control DC 5V operated relays via 3.3V operated ESP8266 without any issues. 
How to use:
- High voltage (5V for example) to the HV pin
- Low voltage (3.3V for example) to LV
- Gound from the system to the GND pin.
Specification
| Number of Channels | 4 |
| Number of Pins | 6 |
| Voltage on Lx Side | 1.8V-5V |
| Voltage on Hx Side | 2.8-6V |
| Power | 2.8-6V |
| Dimension | 16.6x16.6x2.8mm |
| Country of Origin | China |