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- Manufacturer: Pololu
- Order number: EXP-R25-187
- Manufacturer part number: 2485
- Availability: 4
- country of origin: US
- HS code: 85439000
- Weight (kg): 0.034
- Compact layout
- LEDs to indicate coil actuation
- Zener diodes for fast current decay on relay coils
- Specification of electrical routing clearance rules on relay switch nodes
- Our basic relay carrier boards are available in single-channel and dual-channel versions. The single-relay carrier is less than half the size of the 2-channel carrier (due in part to its smaller mounting holes and lack of barrel jack footprints), so it might be more appropriate to use two single-channel boards instead of one 2-channel board in some space-constrained applications. The following table shows some of the key differences between the two versions:
|Voltage options||Board size||Mounting hole size||# of channels||DC power jack option|
|Single-relay||5 V and 12 V||1.15″ × 1″||0.086″ (#2 or M2)||1||no|
|Dual-relay||5 V and 12 V||1.5″ × 1.8″||0.125″ (#4 or M3)||2||yes|
- The switch portion of the relays are accessible on one side of the board while the control pins are routed to the other. The relay coils are powered by supplying 5 V or 12 V across the VDD and GND pins (depending on the relay), and they are activated by digital high control signals on their respective EN pins. The control signals are fed directly to the BSS138 N-channel MOSFETs, which in turn actuate the relay coils when the signal voltage exceeds approximately 2.5 V (see BSS138 datasheet (92k pdf) for details). The control pins 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 servo cables) can be used side-by-side (one for each relay).
- The relay switch terminals COM (common), NO (normally open), and NC (normally closed) are routed on the PCB with a minimum clearance of 60 mils (1.5 mm) from other copper and the edges of the board, 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.
- 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).
- Size: 1.8″ × 1.5″ × 0.9″
- Weight: 33g