https://w.electrodragon.com/w/ESP_Relay_Board_VDC

Analag Input A0

Back Side Jumper Header text
Connect No voltage divider, A0 directly connect to ESP-12 Module ADC pin.
Disconnect A0 input via voltage divider to ADC = 220K / 100K, maximium input A0 3.3V
  • Reference calculation see here: https://learn.sparkfun.com/tutorials/voltage-dividers/all

Specific for Relay Board VDC

Jumper Header text Header text
U2 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 -
Green Out Input Terminal VIN 5-26V / ground -

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

Schematic

version updates

  • 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.

ref