ESP Relay Board Hardware

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  • For Board demo software setup, and debugging see on this page ESP Board Setup

Board Configuration

  • General board configuration

Specific for Relay Board


  • Based on ESP-12F ESP8266 Wifi Board
  • This relay board use one AC input, and supports two relay AC output
  • Use mature AC-DC power module
  • Plastic enclosure design support, package includes the plastic case
  • Two Lead out buttons BTN1 and BTN2
  • Two relay indication LEDs
  • One status LED, indicating connecting status in demo code
  • Resevered design for temperature sensor DHT22
  • Screw terminal which are easy for wiring output

Hardware Update Logs

Update Log for ESP Relay Board

Update R1.6

Update ESP Relay Board R1.6.jpg
  • Optmized lead out pins, IO4, IO5 used for IIC bus, see the demo image here.

Updated R1.5:

  • Optimized board layout, replace a few higher quality parts

Updated version R1.1:

  • Fix isolation and current drop issue on old version, which cause the ESP-wifi board may have a 5% chance to reset/restart when you switch relays On/Off very very frequently.  R1.1 version is not absolutely can be eliminated this issue since the onboard AC-DC module has a limit, but the probability of this problem should be controlled to the least, low to one percent.
  • Maximum trace design for current passing, 2MM trace width to let 2A current pass through roughly for two relays together, so either 2A for running one channel device or 1A for two device. also open trace without soldermask, you can add more solders to get even higher current passing.

Specific for Relay Board VDC

  • Jumper U2 for wireless RF receiver, output TTL signal to ESP12F pins, DO -> IO2, D1 -> IO15
  • JP2 -> Alternative power supply pin 5V-24V, = terminal power input
  • JP7 -> Power input selection, choose between 5V or 5-24V.
  • JP1 -> DHT, ADC, RST
  • JP6 -> row 1: RXD, TXD, 5V, GND, row 2: 3.3V, IO4, IO5, IO15

Update Log for ESP Relay Board VDC

  • V4.2 added voltage divider on back side of PCB, this need to be soldered manually.
  • V4.1 pin headers changed to two group. RST, ADC and DHT_IO16 pins on left side now.

Use of AC Main Power IN to Relay

  • to switch to control AC mains power, need to remove two 1206 0R resistors on board. Then power from left green terminal = relay output (and terminal)
  • To supply power on board control circuit, add 6-24V power to "ALT VIN" pins

Add-Ons Functions


IO4 and IO5

  • IO4 and IO5 hs pull up resistors for IIC bus to use
  • Demo code for IIC OLED screen for LUA can be found at nodemcu github, /master/lua_examples/u8glib/ this folder, or click here to browse.
  • To remove the pull-up resistor, find the 2x two-very-close-pin on the right side of break away header pin 4 and pin 5, use knife to cut them, then 4.7K resistor will be disconnected. Also can add solder to re-connect them later.

DHT Sensor

  • Please connect the board to sensor by wires, because the PCB and relays will generate heats!!
  • DHT22 support plug on to use, feel free to use wires or socket to settle the DHT sensor, pin definition is 3V3, data, NC and GND
  • Default firmware has DHT module enable, upload example code will work directly. demo code here., or download lua sketch, in esplorer run DHT22.lua direct to read temperature humidity

General Pin Definition

  • Pin Definition for standard esp relay board, relay VDC board, relay SPDT board.
ESP8266 Pins Board Pins Note Function
IO12 Relay 1 - relay 10A load max.
IO13 Relay 2 - relay 10A load max.
IO16 Status LED - -
IO14 reserved DHT22 socket pull-up 10K resistor
IO4 DHT22 pull-up 4.7K resistor, can be disconnected
IO5 DHT22 pull-up 4.7K resistor, can be disconnected
IO0 button BTN2 pull-up 10K resistor Hold down then power up to enter into flash mode
IO2 button BTN1 - programmed for clear config from code version 1.2
IO15 - - -


B004 box.jpg
  • Case size see on the image.

Projects (if you want list please let me know)

Schematics, Dimension