10-30-2017, 03:59 PM
(10-29-2017, 07:00 PM)trainspotter139 Wrote:(10-29-2017, 04:44 PM)Canard Wrote: 1/2 - Sunday, October 29, 2017
A couple of notes from today;
- The little orange light was blinking at Borden station today, on the OCS pole! Does that mean the power is on? It was blinking on for about 0.1 second, off for about 0.6-0.7 seconds (ie, a little faster than 1 Hz, maybe 1.4 Hz or so).
It probably does mean that. Though it would be a more useful indicator if it was a solid light or a frequently blinking one rather than 0.1 seconds on 0.6-0.7 seconds off.
Making it blink is probably an easy way to handle the wide range of input voltages.
The nominal voltage of the OCS is 750V, but the max is 900V and under the heavy load of two accelerating double trains it's permitted to drop as low as 525V. By using a relaxation oscillator (think of the whine of a charging camera flash) to build up X amount of charge and then dump it into the light for Y amount of time, X can vary with the voltage: You get a slower blink at the lower voltage and a faster blink at the higher voltage, but the duration and brightness of the blink is always the same.
...K