The Pololu basic relay carrier modules make it easy to control a single-pole, double-throw (SPDT) switch from low-voltage, low-current control signals.

The carrier board routes the three relay control pins to 0.1″-spaced pins compatible with standard solderless breadboads and female servo cable connectors.

You can search more details in attached schematics or on http://www.pololu.com/catalog/product/2481

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