Stackable Raspberry Pi add-on has four switched relays
Apr 28, 2020 — by Eric Brown 2,368 viewsSequent Microsystems has launched a $20 “4-Relay” add-on for the Raspberry Pi with four line-switching relays for loads of up to 10A and 250V. The cards can stack up to 8x high for 32 switched relays.
Sequent Microsystems has won Kickstarter funding for a Raspberry Pi add-on card designed to switch multiple lights or appliances. Unlike Sequent’s earlier Raspberry Pi 8-Relay Card, which can stack 8x high for 64 relays, the new 4-Relay card offers switching capability between the relays, with support for up to 10A and 250V loads on each relay.


4-Relay (left) and with Raspberry Pi stacked five high
(click images to enlarge)
Sequent has won funding for its Kickstarter campaign, which runs through May 21. You can buy a single card for $20 or two for $36, with shipments expected in July.
Designed for the Raspberry Pi B+, 2, 3, or Zero, the card uses only 2x RPi GPIO pins, and passes along the GPIO pins for other HATs to stack on top. With the help of 18mm male-female standoffs supplied by Sequent, you can stack up to 8x 4-Relay cards for 32 switched relays.


4-Relay block and conceptual diagrams
(click images to enlarge)
Each relay has a pluggable connector that accepts 18 to 22 AWG wires. This is said to “simplify the installation, especially if you are planning to use more than one card.” The 4-Relay runs on 5V power either from an external supply or the Raspberry Pi.
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The card can be mixed and matched in a stack with the 8-Relay cards, although you need a new command line function. A Javascript example program is supplied along with command line and Python drivers.
Further information
The 4-Relay card is available on Kickstarter for $20 through May 21 with shipments due in July. More information may be found at the Sequent Microsystems 4-Relay Kickstarter page.
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