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VariLink - The Universal long range controller

Looking for something specific?

FieldTech are proud to manufacture our products here in the U.K in-house. Fully equipped with a Printed circuit board Production line, and an electronic workshop capable of conjuring a whole host of systems. If there's something specific you need, drop us a message. We will be pleased to work with you to see if its a product we can deliver.

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Supplied as two units











Forget the limitations of conventional transmitters & receivers, Transceivers communicate in both directions!
What's the benefit? If you take our product listing image as an example, you can see we're demonstrating the unit with a float switch, and next to it is an LED indicator light. When the float switch is activated, the signal is sent to the other unit activating the relay output which in turn powers the contactor, energising the pump. So how would we know that this has happened two miles away? well this is the beauty of a transceiver. With the mimic jumpers in place, once the command has been received, a signal is then sent back to the controller confirming that this has occurred. This allows you to connect an LED indicator light (or anything else) to the output Relay of the controller.

Thats right! BOTH units have Two inputs, and two outputs (actually three including the supervisor alarm, but more on that further down), giving you a whole host of options for monitoring the remote location. We will list some different scenarios below as examples.

Please note! you will receive two units complete with antennas. Accessories such as switches, lights, contactors, pumps are not included.

  • 2 Mile Range with included Antennas

  • 868Mhz Licence free - no costs associated to use the system.

  • 100mw power to meet UK Law, and can still cover two miles with the entry level included antennas

  • upto 65,000 possible addresses, preset by us upon dispatch.

  • Authenticated communication between devices to ensure interference cannot trigger the unit.

  • Two non voltage Inputs on each unit suitable for latching switches, or momentary switches which exceed a closed contact of 500ms when using the mimic feature.

  • Two outputs on each unit

  • Supervisory Relay, changes state if power or signal is lost on either unit.

  • Power Input 6-32V DC

  • Current consumption 10mA in standby, 100mA with supervisory relay enabled.

  • 4 x 20mm cable glands are also included but not fitted. if you would like us to fit them for you please ask!

  • Manufactured in the U.K by FieldTech

VariLink, aptly named as its variable to suit the needs of many applications, can be easily configured by yourself to act in different ways by simply changing the jumpers shown in the second picture. Here is a description of the jumpers and their functionality:









SOUND: The unit beeps each time either a relay changes state, or an input changes state. If you would prefer the unit to be silent, then remove this green jumper.

M1 & M2: These are Mimic Jumpers, for channel 1 & channel 2 respectively. For instance, with M1 on, when channel 1 receives a signal to activate its relay, it will send a signal back to the sending unit and activate it's channel 1 relay - mirroring the state of the relay in both locations. This allows you to connect visual indicators to the controller unit so that you may see the status of the device two miles away. The same applies to channel 2's jumper M2. Remove the jumper, and the signal will not be sent back to the controller unit. When removed, you can use the input terminals instead to send feedback to the controller unit. This gives you a greater level of precision so that you could connect a vibration sensor, a flow sensor, a door contact, to its input. when this sensor changes state, the signal would then be sent back to the controller unit, changing its mimic'ed relays state.


LOGIC: The units have Two Dry (non voltage) inputs each. with the logic jumper on, the unit expects a normally open switch. If you remove the jumper, the system will expect a normally closed switch.


LATCH: When this jumper is removed, the relay outputs will latch on when activated. This enables the reset screw terminals on the receiving unit. You will need  to connect a push button switch to these terminals. Once pushed, the relays will reset.


DOG: Controls the Watchdog Supervisory Relay. with the jumper on, when you power on the unit the supervisory relay will change state and will remain constantly powered. If you are running one of the units on battery power, you can reduce its current consumption from 100mA, to 30mA by removing this jumper. This prevents the relay from changing state on power up. This will however prevent you from connecting a supervisory alarm to the supervisory relay on this unit, as it will no longer change state at this location. Remember that the other unit can still have its DOG jumper on, and an alert can be connected to that unit instead, which may be powered by a transformer.

Supervisory Feature: Every 30 seconds the decies will ping each other to confirm they can still see each other. if not, the supervisory relay will change state, giving you the option to be notified of the problem.

Scenarios as examples - For clarity, we will refer to one unit as the controller unit, and the other as the receiving unit.

Irrigation control:
On the controller unit, we will install a float switch, or a latching push button switch to input 1
Also on the controller unit, we will install an LED indicator to Relay 1
On the Receiving unit, we will connect a pump to Relay 1, and leave the Mimic 1 jumper on.

In Operation: The float switch changes state and the signal is sent to the receiving unit, which turns on the relay activating the pump. Once actioned, a signal is sent back to the controller unit, activating the relay to illuminate the LED Indicator.

Gate control:
On the controller unit, we will install two momentary push switches. one to open the gate and the other to close.
Also on the controller unit, we will install a red and a green light to the same relay using the normally open and closed terminals, to show if the gate is open or closed.
On the receiving unit, we will remove the mimic jumpers. This allows a momentary push without being constrained to the minimum of 500ms. We will install a gate contact to Input 1.

In Operation: You can now send open and close commands to the gate, and receive a live indication as to whether the gate is open or closed. You could also connect a PIR sensor to the other input. This way when a vehicle arrives, a notification is sent back to the controller unit, which could have a buzzer connected to it.

Light Control
On the controller unit, we will connect a latching switch. and a status light.
On the receiving unit we will connect a contactor to energize the lighting circuit.

In Operation: When the switch is turned on, the contactor will energize at the remote location. The signal will be sent back to the controller unit to confirm this has occurred by illuminating the status light connected to the relay.

Light Control scenario 2
On the controller unit, we will connect a latching switch. and a status light.
On the receiving unit we will connect a contactor to energize the lighting circuit.
Also on the receiving unit, we will remove the Mimic Jumpers and connect a photocell to Input 1

In Operation: The system will now behave as it did in the last example, but now it will only send a signal back when it physically detects light in the location from the photocell. This ensures that the fuse or light bulb hasn't blown.

Generator Control:
By connecting a vibration sensor to the input of the receiving unit, you can send feedback back to the controller unit that the generator is running.

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