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VG-RELAY-LATCH: Latching Relay Board
| This board is perfect for blocking irrigation
clock pulses to latching valves.
Drawing only 65uA during normal operation,
this board is perfect for applications where battery life is
critical. It interfaces directly to Vegetronix
moisture sensors, and has a variable
resistor which set's the relay trigger point. Because it uses a
low power latching relay, it only requires a brief pulse of current
to update the state of the relay. The soil moisture sensor is
sampled every 10 minutes to update the state of the
It has 2 LEDs to indicate that the
board has power, and the on/off state of the relay. For low power
mode the LEDs can be disabled with a simple jumper switch.
It can be wired in series to valves including
latching valves and block
watering events from a valve clock.
The VG-RELAY-LATCH board interfaces to a single
VH400 soil sensor, and can activate a low power AC load such as a valve
or alarm, or other control device, when a moisture level is reached.
The threshold is easily set with the onboard variable resistor, and
a small screwdriver. The
relay board can be configured with a jumper to turn the relay on
when the sensor detects wetness or on when the sensor detects
This board has a special configuration mode,
which can be entered by setting a jumper. In configuration
mode, the LEDs are active, and the sensor and variable resistor are
continuously updated. This mode consumes more power, so it
should not normally be used beyond initial calibration.
The VG-RELAY-LATCH also serves as an evaluation
board. If you are thinking about testing our VH400 soil
moisture sensors you should consider purchasing this board as
Moisture Sensor Relay
VG-RELAY-LATCH Block diagram.
Showing interface to Valve and VH400 Soil Moisture Probe.
- Battery operated valves and control
- Perfect for evaluating our VH400 soil moisture
- Interruption and control off irrigation and
- Interface soil moisture sensors to home
- Control and monitoring of moisture content in bulk foods.
- Rain and weather control functions.
- Environmental control functions.
- Water conservation applications.
- Fluid level measurements and control.
- Wide AC input voltage range.
- Samples the sensor and updates the relay
approximately every 10 minutes.
- Has a special real time configuration mode, where
LEDs are active and the sensor and variable resistor are read
- Can be configured as a normally open or normally
closed contact with a simple jumper setting.
- Uses a low power solid state relay.
- Can control a 10A load up to 240VAC.
- Interfaces to a single VH400 probe.
- Low power.
- LED indicators, indicate power on and relay
- Terminal blocks for quick connection.
- Low price.
- Small size.
- 4 mounting holes in each corner.
- There is a jumper on the board, namely J2. (It's a black 2
pin header.) Make sure it is shorted with the black plastic
jumper. When it arrives this should have already been
shorted with the jumper.
- Insert the sensor into terminal block TB2. Red wire to +5,
Black to Sense, and Bare wire to GND.
- Power the board with 9VDC, or 9V battery to terminal block
- If the jumper is on correctly, the power light should come
on. The LED D4, says "POWER ON" underneath it. If the power
light doesn't come on and the jumper J2 is in place then you've probably hooked up
the power incorrectly.
- The relay LED will now also be operational with the jumper
in place, but with there is a nuance to it. The potentiometer
is only read about ever second - it is not continuous. So you
must adjust it very slowly, and incrementally. If you turn it
to fast, it wont be read and you will overshoot.
- Adjust the pot until you have it at the correct level. The
LED light will either turn on when it passes the threshold set
by the pot, or off when it has not.
- The polarity jumper J3 can be used to reverse the polarity
of the relay, from normally closed to normally on. This can
also be used to verify that the relay light is working. If
the relay light is off, it should turn on with one of the
cases: of the jumper being inserted, or removed.
- Once the board is calibrated, remove the jumper from J2, so that the LEDs do not waste power.
(You can put it on just one of the pins, so that you save it
for future use.)
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
For volume pricing contact
| ORDER INFO
| Part Number
|| Latching relay board for the VH400 probes.
Interfaces to a single VH400 Moisture Sensor Probe.
| Power consumption
| Supply Voltage
|| 6V to 24 VDC
| Relay Load
|| 10A 250VAC
|| 2.0"x1.75" (5.08cm x
| Number of sensor interfaces
| Number of relay outputs
Terminal Block TB1 (INPUT
|| 6 to 24VDC
Terminal Block TB2 (SENSOR
|| GROUND: (connect to probe ground -
|| SENSE: (connect to probe output -
|| POWER: 5V (connect to probe
power - red wire)
Terminal Block TB3 (RELAY
|| Relay contact 1
|| Relay contact 2
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.