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Pump and Valve Relay Switching Board


  • Adjust the trigger threshold with a thumb wheel.
  • Powered from a wide range of DC supplies.
  • Can be configured as a normally open or normally closed contact with a simple jumper setting.
  • Uses a mechanical relay.
  • Can control a 10A 250V load.
  • Interfaces to a single VH400 probe.
  • Low power.
  • LED indicators, indicate power on and relay contact.
  • Terminal blocks for quick connection.
  • Low price.
  • Small size.
  • 4 mounting holes in each corner.


Relay Board for Switching Pumps and Valves

The VG-RELAY-DC board is perfect for controlling traditional sprinkler valves, pumps, or interfacing to other control systems. It interfaces directly to Vegetronix soil moisture sensors. Because it uses a 10A mechanical relay, it can directly control higher power AC or DC devices. It uses 2 LEDs to indicate that the board has power, and the on/off state of the relay.

Easy to Use

The VG-RELAY-DC board interfaces to a single sensor, and can activate a high power AC or DC load such as a valve or alarm, or other control device, when a moisture level is reached. The threshold is easily set by turning onboard variable resistor thumb wheel. The relay's polarity can be configured with a jumper. When the jumper is inserted the relay will engage when sensor detects wetness. and when it is removed the relay will turn off when sensor detects wetness.

Can be Used With Irrigation Timers to Save Water and Money

This relay board can be used as an input to many sprinkler timer controllers, simulating a rain sensor, but giving more accurate feedback to the controller. For more detailed information on how this works see the article "How to Replace a Rain Sensor with a Soil Moisture Sensor"

If your irrigation timer doesn't have an irrigation timer, no problem, you can still use this board to interface with your sprinkler timer, to save water. For more detailed information on how this works see the article "How to Control Multiple Sprinklers with a Single Moisture Sensor"

Evaluate Vegetronix Sensors

The VG-RELAY-DC also serves as an evaluation board which works with all of our sensors. In particular, if you are thinking about testing our VH400 soil moisture sensors you should consider purchasing this board as well.

Vegetronix Modular Building Blocks

We take a modular approach with our product lines. Each product is simple and low cost, and will easily interface to all of our other products. This approach allows you to build any type of application from our basic set of components.

We Want you to be Happy

Ordering is easy and low risk. Since we build our own products at our factory, all of our products are in stock. When you place your order from our website, it will ship same day from our factory, and you'll have it in your hands in just a couple of days. We ship to nearly EVERY COUNTRY in the world.

If you aren't amazed and delighted by your new Relay Board, return it for a refund within 30 days.

Relay Board Selector Guide

Vegetronix offers a variety of relay boards for nearly every application. See our Relay Board Selector Guide for help in determining which board is appropriate for your application.

Other Vegetronix Products of Interest

Pricing and Ordering Info

We ship to nearly EVERY COUNTRY on the planet, directly to you from our factory.

99% of orders ship same day.

Part Number Description Price Purchase
VG-RELAY-DC AC Relay board for the VH400 probes. Interfaces to a single VH400 Moisture Sensor Probe. Buy Now
POWER-ADAPTER-9V-US 9VDC 1A Power Supply Adapter for the US. Buy Now
POWER-ADAPTER-9V-EU 9VDC 1A Power Supply Adapter for the EU. Buy Now
BARREL-TERM Barrel Connector to Terminal Block Adapter. Buy Now

For volume pricing contact us.


Power consumption < 40mA when relay engaged.
Supply Voltage 6V to 24 VDC.
Relay Load 10A at 250VAC maximum load
Dimensions 1.75in by 1.75in
Number of sensor inputs 1
Number of relay outputs 1

Wiring Table

Pin Description
2 DC input 1 (max 24VDC rms)
1 GROUND: (connect to probe ground - bare wire)
2 SENSE: (connect to probe output - black wire)
3 POWER: 5V (connect to probe power - red wire)
Terminal Block TB3 (RELAY INTERFACE)
1 Relay contact 1
2 Relay contact 2

Additional Information

How to Get Started

The best way to get started is to order a few low cost probes and relay boards and try them out in your application.

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