Earlier quoted context omitted.
It is also why white traffic lights no longer mean "go". White means "the red glass lens in front of the incandescent bulb shattered again". Related, from train signals: > The invention of the track circuit in 1872 by William Robinson permitted automatic block signals. Most simply, a low voltage battery current runs up one rail and down the other. As long as current flows from the battery through one rail to the rela…
Train air brakes are similar in failing safely for the same written-in-blood reasons: https://en.wikipedia.org/wiki/Railway_air_brake
Never trust a system that seems to be working
111–120 of 376 posts
Re: Never trust a system that seems to be working
#112They don't teach that in college.
Re: Never trust a system that seems to be working
#113Full thread unroll: https://threadreaderapp.com/thread/1581643197427523584.html
Re: Never trust a system that seems to be working
#114Re: Never trust a system that seems to be working
#115Re: Never trust a system that seems to be working
#116This is why 4-20 mA is a common signaling standard in industrial automation. 4 mA means zero and 20 mA means one. 0 mA means broken transmitter !
It is also why white traffic lights no longer mean "go". White means "the red glass lens in front of the incandescent bulb shattered again". Related, from train signals: > The invention of the track circuit in 1872 by William Robinson permitted automatic block signals. Most simply, a low voltage battery current runs up one rail and down the other. As long as current flows from the battery through one rail to the rela…
Re: Never trust a system that seems to be working
#117Quoted post unavailable.
Re: Never trust a system that seems to be working
#118[flagged]
Re: Never trust a system that seems to be working
#119Reminds me of Jurassic Park (book, I think?); nobody realised that dinosaurs were loose and breeding, because the system was doing: if dinosaurs and nobody anticipated dinosaurs > expected
Re: Never trust a system that seems to be working
#120Earlier quoted context omitted.
Train air brakes are similar in failing safely for the same written-in-blood reasons: https://en.wikipedia.org/wiki/Railway_air_brake
Some military trucks are designed the opposite way on purpose - because they’d rather have no brakes and be able to move than be stuck on the battlefield.