The 8-MOSFETS card is a stackable, DIN-rail mountable, solid-state power driver for the Raspberry Pi.
When looking to drive high loads with a microprocessor, hardware designers typically turn to relays, in part because relatively inexpensive relays are still quite reliable under most circumstances. While they tend to perform well under AC loads, however, they fall short when faced with high DC voltages, fast switching times, and endurance requirements.
This is where the 8-MOSFET comes in - it has four high-current channels which can drive 10A/24V loads and four high voltage channels which can drive loads of 2A/240V.
Industrial Reliability at a Reasonable Price
Designed for the industrial automation market where reliability is critical, the 8-MOSFET card can drive four high-current loads (24 VDC at 10 A) and four high-voltage loads (240 VDC at 2 A). At the same time, its price tag brings it within reach of anyone who appreciates performance and reliability for their home automation projects.
It’s also easy to use - 8-MOSFET employs industrial-grade, pluggable connectors that facilitate field installation and debugging and make the cards easy to use when multiple cards are stacked up. Status LEDs show when MOSFETs are on or off.
Scalable - up to eight cards can be stacked on top of a single Raspberry Pi, giving your Pi the ability to drive up to 64 loads! And because the 8-MOSFET only occupies the I²C interface, you’ll still have 24 GPIO pins to use for other applications.
Traditional relays switch their loads by mechanically moving blades. As a result, their switch time is rather high - typically tens of milliseconds. Furthermore, moving parts tend to vibrate, which creates electrical noise when they make or break contact. For applications that require fast, clean switching times, a MOSFET will get the job done in under 0.1 mS with no electrical noise.
High Endurance Under Heavy Loads
While traditional relays have acceptable endurance when switching low currents, their lifespans shrink to somewhere in the neighbourhood of 100,000 cycles at high currents. So, if a relay needs to switch a large load once per minute, it might reach the end of its life within a couple of months. A MOSFET, by contrast, has nearly unlimited longevity.
The 8-MOSFETS card needs 5V to operate and can be powered from Raspberry Pi or from its own 2.1mm barrel connector. The card draws ~10mA. If power is applied to the barrel connector, no other power supply is required for the Raspberry Pi.
You can control the 8-RELAY card by writing your program in the language of your choice using the Command Line system, or the Python Driver. Controlling the MOSFETS from the browser can be easily implemented using the Node-Red node we provide (coming soon).
The 8-MOSFETS card can be tested before installation by running a simple command from the command line. The card will cycle each MOSFET on and off at 0.5 seconds interval. The lighting of the LEDs will assure that all relays are functioning. Optional loads on each channel can extend the user’s confidence in the hardware.
The card is compatible with all 40-pin Raspberry Pi versions from Zero to 4.
All stacked cards share the I2C bus using only two of the Raspberry Pi’s GPIO pins to manage all eight cards. This feature leaves the remaining 24 GPIOs available for the user.
Two DIN-rail Mounting Options
The 8-MOSFET supports two different DIN-rail orientations:
- Parallel to the Rail - for a single card or a two-card stack, the parallel mounting kit is ideal. While one kit can technically support any number of cards, it becomes mechanically unstable once you get two or three 8-MOSFET cards piled up on your Raspberry Pi.
- Perpendicular to the Rail - Because each card is secured to the DIN rail with a dedicated steel bracket, the perpendicular mounting kit offers mechanical stability for any number of cards. So, even with eight 8-MOSFET cards on your Raspberry Pi, you’ll still have room for other Raspberry Pi add-on cards.
- 8-MOSFETS add-on card for Raspberry Pi
- Eight 2-pin male connector plugs
- Mounting Hardware
- Four M2.5x18mm male-female standoffs
- Four M2.5x5mm screws
- Four M2.5 nylon nuts
- Two jumpers
Quick Start Guide
- Plug your 8-MOSFETS card on top of your Raspberry Pi and power up the system using only one 5V/3A power supply
- Enable I2C communication on Raspberry Pi using raspi-config
- Install the 8-MOSFETS software from github.com:
- git clone https://github.com/SequentMicrosystems/8mosfet-rpi.git
- cd /home/pi/8mosfet-rpi
- ~/8mosfet-rpi$ sudo make install
- ~/8mosfet-rpi$ 8mosfet
- The program will respond with a list of available commands
- Connect your load between pin 2 of any of the load connectors and the positive side of your external power supply
- Connect the negative side of your external power supply to pin 1 of the output connectors
- Turn on and off the load using the corresponding command.
- Weight 100 g
- Dimensions 10cm×7cm×2cm
- 4 each: 10A/24VDC
- 4 each: 2A/240VDC
- Power Supply
- 4.75 – 5.25VDC (2.1mm Barrel Connector)
Payment & Accreditations
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.