ET-MD18
MAX6650 I²C Fan Speed Controller
Set a 12 V fan's RPM over I²C and the chip holds it, with fan-fail alarm
AED 59.00
Out of stockOverview
Set a 12 V fan's RPM over I²C and the chip holds it, with fan-fail alarm
The ET-MD18 is built around the Maxim MAX6650 — closed-loop fan speed regulation from the tach signal, I²C-set target RPM, fan-fail alarm. It connects over I²C (Qwiic) (4 selectable addresses) and is powered from Logic 3–5.5V from Qwiic; fan 12V on a screw terminal (up to ~1A fan).
Two Qwiic / STEMMA QT connectors let you chain it with other boards without soldering, and the 2.54 mm header fits a breadboard.
Designed in Dubai by ElectroTrical — the full schematic, BOM and design notes are published below.
Good for
- Enclosure and rack cooling
- 3D-printer chamber fans
- Fan-fail monitoring
Key features
What makes it different
Controller
Maxim MAX6650: closed-loop fan speed regulation from the tach signal, I²C-set target RPM, fan-fail alarm
Interface
I2C (Qwiic), 4 selectable addresses
Supply
Logic 3–5.5V from Qwiic; fan 12V on a screw terminal (up to ~1A fan)
Fans
Standard 3-wire and 4-wire 12V PC fans (supply switched, tach read)
Qwiic / STEMMA QT
Two JST-SH connectors plus a 2.54 mm header — 3.3 V and 5 V hosts.
Open documentation
Schematic, BOM and layout notes published for every board.
Specifications
Technical specifications
| Controller | Maxim MAX6650: closed-loop fan speed regulation from the tach signal, I²C-set target RPM, fan-fail alarm |
|---|---|
| Interface | I2C (Qwiic), 4 selectable addresses |
| Supply | Logic 3–5.5V from Qwiic; fan 12V on a screw terminal (up to ~1A fan) |
| Fans | Standard 3-wire and 4-wire 12V PC fans (supply switched, tach read) |
| Size | 35.0 × 25.0 mm |
|---|---|
| Mounting | 4 × M2.5 holes, 2.54 mm from each corner |
| Connectors | 2 × Qwiic / STEMMA QT (JST SH 4-pin) · 7-pin 2.54 mm header · Screw terminal 2P 5.0mm 17A (THT) — 12V in |
| Main IC | MAX6650EUB+ (LCSC C143561) |
| Revision | Rev A |
| Libraries | Register-level I²C (Linux max6650 hwmon driver; Arduino/Python examples) |
|---|
| JP1 (default Closed) | Cut to turn off the LED |
|---|---|
| JP2 (default Closed) | Cut to remove the host-side I2C pull-ups |
Performance
Capability
Pinout
Pin map and connections
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | VIN | Power | Sensor supply = host logic level |
| 2 | GND | Ground | Ground |
| 3 | SCL | I²C | I²C clock |
| 4 | SDA | I²C | I²C data |
| 5 | ALERT | Output | Fan fail / over/under-speed alarm, open-drain |
| 6 | GPIO0 | GPIO | Spare GPIO / full-on input |
| 7 | GPIO1 | GPIO | Spare GPIO / clock |
Qwiic / STEMMA QT pins: GND, VIN, SDA, SCL (same on both connectors). I²C pull-ups (10 kΩ) are on the board; cut JP2 to remove them.
Mechanical
Dimensions and what's in the box
In the box
- 1 × ET-MD18 MAX6650 I²C Fan Speed Controller (assembled)
- 1 × 7-pin 2.54 mm male header, unsoldered
Getting started
- Plug in a Qwiic / STEMMA QT cable, or solder the header and wire VIN, GND, SDA and SCL
- Libraries: Register-level I²C (Linux
max6650hwmon driver
Compare
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|---|---|---|---|---|
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| Price | 59 AED | 59 AED | 69 AED | 39 AED |
Downloads
Documents and design files
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