Overview

The Pololu basic relay carrier modules make it easy to control electrically isolated, single-pole, double-throw (SPDT) switches from low-voltage, low-current control signals. The modules are available in single-channel and dual-channel versions with 5 V or 12 V power relays—Omron G5LE-14-DC5 and G5LE-14-DC12 (1MB pdf), respectively—and with a variety of connector and assembly options.

The following table lists the available Pololu basic SPDT relay carrier options:

Alternatives available with variations in these parameter(s): channels voltage style Select variant…

Details for item #2488

This carrier version is partial kit that includes:

• One Pololu Basic 2-Channel SPDT Relay Carrier for "Sugar Cube" Relays, which is populated with all surface-mount components
• Two Omron G5LE-14-DC12 12 V relays, which are rated for up to 10 A under most conditions
• One 1×25 0.1″ straight male header strip and one 1×15 0.1″ right-angle male header strip
• Two 3-pin 5mm-pitch terminal block

These control pins on the carrier board are arranged to allow for several connection options: a single 1×4 cable can be used to supply coil power and the two control signals, or two 1×3 cables (such as female servo cables) can be used side-by-side (one for each relay). The included straight header can be broken or cut into smaller strips and soldered into these control through-holes to accommodate the desired connections. Alternatively, a 1×4 segment of the included right-angle header can be soldered to the outermost row of through-holes. The straight and right-angle headers work with 0.1″ jumper wires.

For the switch connections, you can use a 1×11 segment of either the straight or right-angle header strip and remove every other pin to make a 0.2″-pitch header that can be soldered to the smaller holes on that side of the board, or you can solder the included 5mm-pitch terminal blocks to the larger holes. These terminal blocks should be combined into a single 6-pin block before you solder them. The following pictures show a unit assembled with straight headers and terminal blocks:

Advantages over similar products

• Compact layout
• Two 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 portions of the relays (NCx, COMx, and NOx) are accessible on one side of the board via larger holes that work with the included 5mm-pitch terminal blocks or smaller holes that work with 0.2″ headers. The control pins (EN1, EN2, VDD, GND) are routed to the 0.1″-pitch through-holes on the other side of the board that work with the included 0.1″ straight and right-angle headers. The 12 V relay coils are powered by supplying 12 V 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.

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.

Optional DC barrel jack

The carrier board makes it possible to optionally power the relays from a DC barrel jack (not included). The DC barrel jack can be placed in three configurations, two of which are shown in the pictures above (the jack can also be installed in one configuration on the bottom side of the PCB).

Schematic diagram

Schematic diagram of the Pololu basic 2-channel SPDT relay carrier with 0.1″ headers.

This schematic is also available as a downloadable pdf (128k pdf).