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Is this safe -- emulating supervised circuits?

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  • Is this safe -- emulating supervised circuits?

    I read with interest the dialog on protecting the analog inputs of the ADIO (thanks everyone). My intended application is to use an SIA CP-01 compliant solution for fire safety (the GE NX-8E and NX-148E-RF which I already own) and home automation for security (primarily Form C with tamper protection motion sensors) (let me know if you are interested in my Top Level Design).

    I was going to wire the motion sensors for supervision (individual circuits to each sensor, single or dual end-of-line Zone 9-16 resistors as appropriate). The sensor supervision would be off the ADIO's 5VDC rather than the NX-8E's 12VDC. The next house owner can move the motion sensors to the NX-8E if they want -- I won't be around to care.

    Most of the motion sensors are inside the house where the wiring is unlikely to be damaged. But some of the motion sensors are outside. Much but not all of their wiring is in conduit. San Diego doesn't have weather (I'm 2 miles from the Zoo) but still things just happen (weed whackers for instance).

    So is this adequate protection for the analog inputs or should I add some form of optical isolation? I'd like to keep the supervisory capability which means analog not digital. If I should add optical isolation would you please suggest a pre-fabricated solution as I don't have the tools to build the PNP/NPN, etc semiconductor devices you've been discussing and unlike relays I really don't know what to look for in analog optical isolators.

    Thanks for your assistance.