Single-channel 3.3V relay module on a red board with yellow high/low trigger jumper and blue screw terminals

1-Channel 3.3V Relay Module with High/Low Trigger

$3.99 NZD
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Single-channel 3.3V relay module on a red board with yellow high/low trigger jumper and blue screw terminals
  • Single-channel 3.3V relay module on a red board with yellow high/low trigger jumper and blue screw terminals
  • 1-Channel 3.3V Relay Module with High/Low Trigger, PCB length and width marked in millimetres
  • Underside of 1-Channel 3.3V Relay Module with High/Low Trigger, showing PCB solder joints and mounting holes
  • 1-channel 3.3V relay module with labelled DC+, DC- and IN terminals, H/L jumper, PWR LED and relay contacts
1-Channel 3.3V Relay Module with High/Low Trigger
SKU: REL-1CH-3V3

1-Channel 3.3V Relay Module with High/Low Trigger

$3.99 NZD
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A single-channel relay board for 3.3V boards such as the ESP32, ESP8266 and Raspberry Pi Pico. It runs from 3.3V, switches a separate circuit with relay contacts rated up to 10A at 250VAC, and a jumper sets whether the input switches on with a high or low signal.

Using a 5V Arduino such as an Uno or Nano? Choose the 1-Channel 5V Relay Module instead.

Specifications

Supply3.3V DC on DC+ and DC-
Load limit, AC10A at 250VAC, 15A at 125VAC
Load limit, DC10A at 30VDC
ContactsSPDT: COM, NO and NC
TriggerHigh or low, set by jumper
Input stageOptocoupler
Channels1
ConnectionsScrew terminals
PCB sizeApprox. 51 x 25.5 mm

Datasheets

Full technical datasheetPDFQuick Start guide, jumper setting and first click testPDF

What's in the box

1×
1-Channel 3.3V Relay Module with High/Low Trigger

Assembled board with screw terminals fitted.

Great for

Switching a 12V pump, fan or LED strip from an ESP32
Home automation projects with ESPHome or Home Assistant
Solenoid valves, door strikes and buzzers

Wiring & getting started

  1. Set the trigger

    With power off, move the jumper to H to switch the relay on with a high signal, or to L to switch it on with a low signal.

  2. Power and signal

    Connect 3.3V DC to DC+ and DC-. Join DC- to your board's ground and connect its output pin to IN. Use a 3.3V rail with spare current for the relay coil, not a GPIO pin, and never connect 5V to DC+.

  3. Test before adding the load

    With nothing on the contacts, switch the input. The relay should click and the indicator light, and COM should connect to NO. When released, COM connects to NC.

  4. Connect the load

    Turn everything off. Run the load circuit through COM and NO to switch it on when triggered, or through COM and NC to switch it off when triggered. Stay within the load limits.

Note: Mains voltage can kill. Only wire mains loads if you are competent to do so, fully enclose the board so no terminal or solder joint can be touched, and follow NZ electrical safety rules. Motors and lamps draw a surge at switch-on, so leave margin below the limits.

Frequently Asked Questions

Answers to the questions buyers ask most.

What can this relay switch?
The relay contacts are rated 10A at 250VAC, 15A at 125VAC and 10A at 30VDC. That covers most 12V pumps, fans, LED strips and solenoids. Mains loads must be wired by someone competent to do so, with the board fully enclosed.
Will it work with an ESP32, ESP8266 or Raspberry Pi Pico?
Yes, that is what this version is for. It runs from a 3.3V supply and takes a 3.3V control signal on IN. Power it from a 3.3V rail with spare current for the relay coil, not from a GPIO pin. The supplier does not publish trigger thresholds for the 3.3V version, so check the relay clicks before adding a load.
Can I use it with a 5V Arduino?
Use the 1-Channel 5V Relay Module for 5V boards such as the Uno and Nano. This version needs a 3.3V supply; do not connect 5V to DC+.
Should I set the jumper to H or L?
Use H if your code sets the pin high to switch the relay on. Use L if you are following an example written for active-low relay boards, where the pin goes low to switch on.
What do NO, COM and NC mean?
COM is the common contact. It connects to NC while the relay is released and to NO while the relay is energised. The contacts switch a separately supplied load circuit; they do not supply power themselves.
Does the optocoupler make the complete installation electrically isolated?
The board contains an optocoupler input, but that alone does not establish complete system isolation. Wiring, shared supplies, clearances and the load circuit all matter.

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Why Buy from NZN

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I'm Lukas, an engineering student and maker based in Te Awamutu. NZN grew out of a CNC build that dragged on for months because every missing cable, bolt or electronic part meant another overseas order. I started the shop so Kiwi makers can spend more time building and less time waiting for the next parcel.

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