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SparkFun Qwiic Dual Solid State Relay


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The SparkFun Qwiic Dual Solid State Relay is a power delivery board that allows users to switch two AC loads from a low power microcontroller using the SparkFun Qwiic connect system. The board features two 25A/250VAC solid state relays that utilize the Zero Cross Trigger method so you can toggle two loads on a 60Hz AC carrier signal on and off up to 120 times per second!

An ATTiny84 acts as the "brain" of the SparkFun Qwiic Dual Solid Relay to accept I2C commands to toggle the two relays as well as a few other special commands. The I2C address of the ATtiny84A is software configurable so, if you have a seriously big power project in mind, you could daisy chain over 100 Qwiic Dual Solid State Relays.

Messing with such high voltage is dangerous! We've included many safety precautions onto the PCB including ground isolation between the relay and other circuitry and a milled out area isolating each side of AC. However, with all the safety precautions included with the SparkFun Qwiic Dual Solid State Relay, this is still a power accessory for users who are experienced around, and knowledgeable about high AC voltage. If you're not comfortable with handling AC voltage in this way, you may want to check out the IoT Power Relay instead.

Note: The relays are rated for a max of 25A with forced air cooling. If you do not have forced air cooling, 10A max through the relays is recommended.

The SparkFun Qwiic connect system is an ecosystem of I2C sensors, actuators, shields and cables that make prototyping faster and less prone to error. All Qwiic-enabled boards use a common 1mm pitch, 4-pin JST connector. This reduces the amount of required PCB space, and polarized connections mean you can’t hook it up wrong.


  • Operating Voltage: 2.5-3.6V (3.3V recommended)
  • I2C Address: 0x0A (Default) 0x0B (Alternate via jumper select)
  • Load Voltage Range: 12-280VAC
  • Max Current (Through Relay): 25A(240VAC with forced air cooling)
  • Zero Cross Trigger
  • Normally Open Circuit Only
  • 2x Qwiic Connector