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Sonoff Matter Dry-Contact Switch MINI-D Review

The first-ever Matter dry-contact smart switch: Sonoff MINI-D. Teardown, review, and Home Assistant Integration via Matter.

A while back I wrote an article detailing the usage of dry-contact switches in home automation. In this article, I explain what they are, what they are used for and how they differ from standard wet contact switches and relays. A good example of a dry contact smart switch is the Aqara T2 Dual Relay, which is a Zigbee device.

Sonoff Matter Dry Contact Smart Switch MINI-D Review: Featured Image on SmartHomeScene

Recently, Sonoff have released a similar dry contact module with Matter support. In this review, I’m disassembling, testing and reviewing the new Sonoff MINI-D Matter Dry-Contact Switch Module. It’s available on their ITEAD webstore as well as Amazon.

Related: Sonoff Matter MINIR4M Smart Switch Review

Technical Specification Sonoff MINI-D

  • Name: Sonoff MINI-D
  • Connectivity Standard: Matter
  • Connectivity Protocol: Wi-Fi 2.4GHz
  • Casing Material: PC
  • Power Input: 100-240V~ (50/60Hz), 12-48V⎓1A Max
  • Load Capacity: 24V⎓2A (Resistive), 12/24V⎓8W
  • Net Weight: 34.5g
  • Dimensions: 43x41x21.5mm
  • Price: $12.90 ITEAD | Amazon

Teardown and Package Contents

The Sonoff MINI-D module ships in a small box containing the device itself and a user manual. The packaging is nearly identical to Sonoff’s first-ever Matter switch module, the MINIR4M, also known as the MINI EXTREME.

Sonoff Matter Dry Contact Smart Switch MINI-D Review: Package Contents
Sonoff MINI-D Package Contents

On the top of the case, there are 9 terminals in total. The top three, labeled as NO, COM, and NC, are used as the dry contact output. The bottom six terminals are labeled as N, L, S1, S2, DC+, and DC-. These are used for power input and controlling signal connections, with N and L for AC power, S1 and S2 for switch inputs, and DC+ and DC- for optional DC power input.

The bottom contains the Matter QR pairing code along with some basic information about the device.

Sonoff Matter Dry Contact Smart Switch MINI-D Review: Top View
Sonoff MINI-D Top View
Sonoff Matter Dry Contact Smart Switch MINI-D Review: Bottom View
Sonoff MINI-D Bottom View

I opened the MINI-D by prying it open with a small screwdriver. The main board includes several key electronic components: a relay for switching loads, capacitors for voltage smoothing, an inductor for power regulation, and various resistors and diodes for circuit protection and signal processing. The main communication module is positioned vertically on one side, along with the control and pairing button.

On the bottom side, the MINI-D includes multiple ICs, resistors, capacitors, and diodes for processing and power regulation. The soldered traces connect various circuits for efficient data flow and power distribution. It seems very neatly designed and manufactured.

Sonoff Matter Dry Contact Smart Switch MINI-D Review: PCB Top
Sonoff MINI-D PCB Top View
Sonoff Matter Dry Contact Smart Switch MINI-D Review: PCB Bottom
Sonoff MINI-D PCB Bottom View

The Sonoff MINI-D uses the Espressif ESP32-D0WDR2-V3 [Datasheet] for communication and Matter support. The pink material covering the communication module is a thermal pad. This pad is used to provide insulation and thermal management for the module, dissipating heat generated during operation to ensure stable performance and longevity.

The relay is labelled as model FANHAR W11-1C2STL [Datasheet], rated for 5A at 250V AC or 30V DC, making it suitable for a wide range of dry switching applications in both AC and DC circuits. As the MINI-D operates as a dry contact relay, no current is passed to the positive terminal, ensuring isolation between the control circuit and the switched load.

Sonoff Matter Dry Contact Smart Switch MINI-D Review: Communication Module
Sonoff MINI-D PCB Side View

Installation and Wiring

Wiring the Sonoff MINI-D is very simple in terms of knowing how, but you do need to be aware of a couple of things. First, it’s important to understand what dry switches are. They have a huge application in home automation and can be used for a variety of things.

Sonoff have provided a simple wiring diagram for the MINI-D:

Sonoff Matter Dry Contact Smart Switch MINI-D Review: Dry Wiring
Sonoff Matter Dry Contact Smart Switch MINI-D Review: DC Low Power Wiring

The dry contact wiring setup for the Sonoff MINI-D allows it to control external devices without directly powering them. The device can be powered by either AC input (100-240V AC) or DC input (12-48V DC), connected to the respective terminals (“N” and “L” for AC or “DC+” and “DC-” for DC). The external circuit is connected through the “NO” (Normally Open), “COM” (Common), and “NC” (Normally Closed) terminals. This is suitable for thermostats, garage controllers or irrigation system requiring a simple switch.

The DC low-power load wiring configuration for the Sonoff Mini-D allows it to control devices with a maximum load of 8W, such as small DC motors. The device can be powered by either AC (100-240V AC) or DC (12-48V DC) inputs, connected to the respective terminals (“N” and “L” for AC or “DC+” and “DC-” for DC). The controlled load is connected to the “NO” (Normally Open), “COM” (Common), and “NC” (Normally Closed) terminals. You will notice that the wiring is exactly the same, except there is an external power supply powering the DC motor shown in the diagram. This example is given only to support and showcase the maximum current supply the relay can handle. It functions exactly like the previous example.

In both cases, the relay can be controlled by wiring an external switch to the S1 and S2 terminals of the Sonoff MINI-D. In both cases, no current is supplied from the N, L, DC+, DC- terminals to the NO, NC, COM terminals.

Home Assistant Integration via Matter

The Sonoff MINI-D is a Matter-over-Wi-Fi smart switch. I would have preferred to see Sonoff use Thread instead of Wi-Fi, but so far they’ve been releasing only Wi-Fi devices. To integrate this module in Home Assistant, you need to have a Matter server running on your home network. The easiest way to do this is by installing the Matter Add-on in Home Assistant OS.

The pairing and onboarding is as simple as any other Matter device. You simply scan the QR code with your phone and add it to Home Assistant, confirming the one or two prompts along the way. Once added, here’s what it exposes to HA:

Sonoff Matter Dry Contact Smart Switch MINI-D Review: Added to Home Assistant
Sonoff MINI-D Added to Home Assistant via Matter

The switch entity toggles the dry relay in the MINI-D. The power-on-behavior is a nice addition to this Matter device, allowing you to control the state of the switch after a power loss. Response time is immediately in my network, without any delays.

Testing the Dry Contact Relay with a Multimeter

To make sure the Sonoff MINI-D operates the way it should, I conducted two simple tests with my trusted Kaiweets KM601s Multimeter. First, I wanted to find out the NO, NC and COM terminals operate correctly. And second, I wanted to find out if there is any voltage bleed to any of the terminals, which would be an issue.

Sonoff Matter Dry Contact Smart Switch MINI-D Review: Voltage Test
Sonoff MINI-D Multimeter Test

For the first test, I set the multimeter to Continuity Mode, which emits a beep whenever the circuit is complete (shorted). I connected the COM probe to the COM terminal and the V probe to the NO terminal. When the relay was turned on, the multimeter beeped, indicating the circuit was closed. Toggling the relay stopped the beep and instead closed the NC and COM terminals. Moving the red probe to the NC terminal provided a beep confirmation again, verifying that the relay is operating correctly.

For the second test (shown in the image), I wanted to check if there was any current leakage from the internal components to the NO and NC terminals. Fortunately, there was none, as I got a reading of 0V with the relay both turned on and off, confirming that it is a true dry contact relay.

Final Thoughts

The Sonoff MINI-D turned out to be a solid and reliable dry-contact relay. It paired quickly and without issues to my Matter server running in Home Assistant. I highly appreciate the fact that the QR code was hard printed onto the device case, as lost Matter QR codes are a thing now.

If you find a use case for the Sonoff MINI-D, I can comfortably recommend it. Here where it’s available:

Sonoff Matter Dry Contact Smart Switch MINI-D Review: Where to Buy

Sonoff MINI-D Dry Contact Switch

Matter (Wi-Fi)

100-240V AC, 12-48V DC

24V⎓2A (Resistive), 12/24V⎓8W

Matter

Alternatives:

Aqara T2 Dual Relay Module with Energy Monitoring

Zigbee, dual output terminals, possibility to make it wet contact relay.
Tuya Zigbee Dry Contact Smart Switch ZG-001
Zigbee, AC/DC powered, multi-channeled versions available.

6 thoughts on “Sonoff Matter Dry-Contact Switch MINI-D Review”

  1. Hey, thanks for the review!
    Could you please elaborate on what the difference is between this switch and the SONOFF MINIR4M?
    Isn’t it pretty much the same?

    Reply
  2. easy question
    what do you think about the relay rated for 5A at 250V AC or 30V DC and the declared maximum power from datasheet in just 8W 24Vdc? Commercial conditions with other manufacturers?

    Reply
    • Well, since dry contacts are used in kind of a specific scenarios, I think it matches the intended use case quite well.
      However, you are right. They could have used something bigger. My guess is cost, size, and maybe heat dissipation.
      I don’t think there’s anything to do with commercial conditions.
      In all fairness, If you know what you’re doing, this relay will last forever.

      Reply

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