27 Aug
2011
27 Aug
'11
12:18 p.m.
Pete Turnbull wrote:
Everything seems to be based on
voltage thresholds these days, and the shortcomings of that were brought
home to me today in discussion with a building management systems
installer advising that the signaling from a leak detector would not
travel several hundred feet without an (expensive) booster box at each
end. We're not talking about fast baud rates here, just some remote
sensing device with an output consisting of voltage-free relay contacts,
feeding equipment that provides a voltage to distinguish "on" this
morning from "off" this afternoon.
Weird... so why are the boosters so expensive? Just because they need
battery back-up in the event of a power failure?