The switch portions of the relays (NCx, COMx, and NOx) are accessible on one side of the board via larger holes that work with 5mm-pitch terminal blocks or smaller holes that work with 0.2″ headers. The control pins (GND, VDD, EN1, and EN2) are routed to the 4-pin JST SH-style connector on the other side of the board. The relay coils are powered by supplying the relays’ rated coil voltage across the VDD and GND pins, and they are activated by digital high (2.5 V to 20 V) control signals on the respective EN pins. The control signals are fed directly to BSS138K N-channel MOSFETs, which in turn actuate the relay coils when the control voltages exceed approximately 2.5 V, up to a maximum of 20 V (see BSS138K datasheet (517k pdf) for details). Each relay has a corresponding red LED that lights up when the relay coil is active. The carrier board has four mounting holes that work with #4 or M3 screws.

• The relay switch terminals COM (common), NO (normally open), and NC (normally closed) are routed on the PCB with a minimum clearance/creepage of 60 mil (1.5 mm) from other copper. The copper traces are designed to be at least 45 mil (1.1 mm) from the board edges, though manufacturing variations in the board edges can make those distances slightly lower.
• In most applications, the current and voltage ratings for the module will match the ratings of the relay used. Maximum current, maximum voltage, and life expectancy are interdependent; we therefore recommend careful examination of your relay’s datasheet.

Note: This product does not include relays or connectors for the switch pins. The board works with single-pole, double-throw (SPDT) power relays that have the common “sugar cube” pinout and footprint. Versions with relays included are also available (see the selection table near the top of this page).

Advantages over similar products

• Compact layout
• LEDs to indicate coil actuation
• Zener diode for fast current decay on relay coil
• Specification of electrical routing clearance/creepage rules on relay switch nodes

Using the relay module

The switch portion of the relay (NO, NC, and COM) is accessible on one side of the board via larger holes that work with 5mm-pitch terminal blocks or smaller holes that work with 0.2″ headers. The control pins (EN, VDD, GND) are routed to the 3-pin JST SH-style connector on the other side of the board. The relay coil is powered by supplying the relay’s rated coil voltage across the VDD and GND pins, and it is activated by a digital high (2.5 V to 20 V) control signal on the EN pin. The control signal is fed directly to a BSS138K N-channel MOSFET, which in turn actuates the relay coil when the control voltage exceeds approximately 2.5 V, up to a maximum of 20 V (see BSS138K datasheet (517k pdf) for details). Red LEDs on either side of the relay light up when the relay coil is active. The carrier board has four mounting holes that work with #2 or M2 screws.

• The relay switch terminals COM (common), NO (normally open), and NC (normally closed) are routed on the PCB with a minimum clearance/creepage of 60 mil (1.5 mm) from other copper. The copper traces are designed to be at least 45 mil (1.1 mm) from the board edges, though manufacturing variations in the board edges can make those distances slightly lower.
• In most applications, the current and voltage ratings for the module will match the ratings of the relay used. Maximum current, maximum voltage, and life expectancy are interdependent; we therefore recommend careful examination of your relay’s datasheet.

Warning: This product is not designed to or certified for any particular high-voltage safety standard. Working with voltages above 30 V can be extremely dangerous and should only be attempted by qualified individuals with appropriate equipment and protective gear.

Schematic diagram

Package Includes:

• 1 x Pololu 5667 Basic 2-Channel SPDT Relay Carrier for "Sugar Cube" Relays with JST SH-Style Top-Entry Connector