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LRP2000 Passive Reader/Writer
32
Figure 28: Sourcing Output 'Contact
Figure 28 shows a relay connected as a current sourcing “Contact.” The relay is grounded and the +OUT
terminal goes to the positive supply. The diode across the relay coil is essential to protect the output circuit
and reduce noise along the wiring. It should be connected at the relay to minimize the length of wiring that
could radiate noise. A 1N4001 or similar diode may be used.
Figure 29: Sinking Output 'Contact
Figure 29 shows a “Contact” sinking current from a relay. The -OUT terminal is grounded and the relay
goes to the positive supply. This configuration must also have a diode across the relay coil to protect the
circuit and reduce noise.