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Machine Design

Wireless, Energy-Harvesting Switches Transmit Data More Than 900 ft.

Wireless AFIS rocker and snap switches can harvest the energy needed to send a radio message containing all user data via an antenna.

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The AFIS rocker and snap switches from Cherry Industrial Products, which will become ZF in 2017, need no wires for power or to deliver data signals. These truly wireless devices instead harvest energy from the act of a technician or manager pushing the rocker or snap switch. Activating the switch moves a magnet and that motion affects an electromagnetic generator, letting it create an electrical impulse. The impulse is temporarily stored before being converted into a predefined voltage supply by a voltage converter. This provides all the voltage needed for the switch’s RF electronics to send a radio message containing all user data via an antenna.

The switches operate on 868 MHz and 915 MHz, sending up to three data “telegrams” 984 ft. in open areas or 98 ft. inside buildings. Users can transmit information as a proprietary, customer-specific protocol or with RF standards such as KNX-RF or ZigBee. An available receiver can be used to pick up signals from serval switches.

The switches operate in temperatures from –40° to 185°F, with the rocker switch having a life of at least 100,000 operations and the snap switch lasting at least 1,000,000 operations. The switches are also sealed to have an IP40 rating.

For companies new to wireless switches, the firm makes an Energy Harvesting Evaluation Kit that fully demonstrates the technology and lets technicians test its behavior, measuring signal strength and range. The kit includes an energy-harvesting switch, wireless snap switch and rocker switch, receiver, USB cable, antenna bushing, and manual.

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