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COS / COR Input Buffer Board

A COS/COR input buffer conditions a radio's busy/squelch output into a clean logic level for the node — adding pull-ups, polarity handling, opto-isolation, and input protection. Why it matters: Radio COS outputs vary wildly (open-collector, active-high, active-low, 5V, 12V). Feeding them raw into a Pi or CM108 GPIO is unreliable and can be unsafe. A buffer normalizes the signal so ORLP's carrier detect is solid. Use: Especially relevant for commercial radios and repeaters where you tap a discrete COS line rather than relying on software (VOX/DSP) squelch.