LSOR author clarification of capacitor in parallel with LEDs in signal head

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Krigare1
Posts: 4
Joined: Wed Aug 16, 2017 2:53 am

LSOR author clarification of capacitor in parallel with LEDs in signal head

Postby Krigare1 » Sun Aug 20, 2017 1:53 pm

From the LSOR related author: This is my first posting on this forum and hope you will excuse any errors in procedure I maybe committing. After learning of the posted discussions about the purpose of the capacitors connected in parallel with the LEDs used in my block signal face plate article ( 2017 Mar/Apr issue of Live Steam and Outdoor Railroading ) "Iconic Railroad Fixture Gets a Redo", I thought I would help clarify their usage. The face plate circuitry is connected to a controller circuit board via a dedicated underground cable run. The LEDs are switched by an IC on the controller board which has multiple open collector style outputs with active LOW states. The capacitors in question are indeed "overkill" and rarely used in most applications, however in this instance I added them to simply serve as another level to dampen or suppress any potential RF or EMI radiated energy from nearby cell towers and multi use transmitters that could to cause the LEDs to flicker from the cable runs which in turn act like antennas thanks to the floating or "open" inactive state of the IC outputs. There is a negligible benefit of transient protection with the capacitors. During daylight ops the flickering should not be noticeable, however when night running occurs and keeping in mind the high optical magnification of the semi-spherical lens, there would be an increased possibility for some LED flickering to be seen near the front of the face plate. This flickering would be somewhat awkward at night especially when the signal system is off. I hope my explanation here has satisfied all on this subject and sincerely appreciated the attention it has drawn, THANKS to those members that posted about these capacitors. - Dan

SCBryan
Posts: 22
Joined: Tue Feb 10, 2015 12:37 pm
Location: Fort Wayne, IN

Re: LSOR author clarification of capacitor in parallel with LEDs in signal head

Postby SCBryan » Mon Aug 21, 2017 8:06 pm

What was your source for the lenses you describe in your article?


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