Pulsing Headlights.

[Nodrog1826]

Observed something yesterday whilst uploading this video.

https://www.youtube.com/watch?v=89-rj6TpOWQ&list=UUP1cvtGx-WP0yPqEBm4_7tQ

The head/tail lights on the Crok are pulsing, you can see as the loco drives towards you at approx 18 seconds, and then at the end.

Its not something I have noticed myself from looking at the lights, maybe its the camera, any thoughts?

 

[muns]

It probably relates to the frequency of the Pulse Width Modulation used for the lights and the frame rate of the camera.

 

[tramcar trev]

Similar situation as to why wagon wheels appear to go backwards ie the frame rate, speed and the leds.... If its not apparent to the naked eye then its not worth getting excited about....

 

[Madman]

I've noticed that effect on quite a few videos. Most likely what Muns indicated.

 

[Steve]

Its Bu99ered Gordon send it down here and i will dispose of it through the WEEE directive

 

[Nodrog1826]

WEEE have a straight forward answer for the sending it there Steve!!!!!

BTW,

Whilst I am pleased to see people think its the camera, been looking at other vids of mine, but no pulsing lights to be seen.

 

[PhilP]

Not the camera exclusively, but a combination of the switching frequency of the (chopped) voltage to the lights, and the 'frame-rate' (capture-rate of sensor?) in the camera..
Are the lights in this one LED's by any chance? - They turn off/on quicker than a (cooling) filament, and that may make the problem more noticeable??

All conjecture, of course!

 

[Nodrog1826]

Bog standard 5v bulbs, that's what is fitted in all three locos and the coaches...

 

[mibema]

Well, it's the Pulse-width-modulated Voltage of Onboard-Dcoders. Thy drive allways the full DCC-voltage but PWM'd.

Old Decoders from LENZ and early MAssoth have 120Hz frequency, later MAssoth 400 Hz which is much better.

Lights on LGB-motherboards with 5Volt Regulation, where the Decoder is just interfaced, do not have flashing effect.

Just stand-alone decoders have because of no analogue regulation. .

Another feature is to have wrong count of driving steps (14 on decoder and 28 on central station), then you will have front-ligntening just on every second speed-step...

Coach-lightening also has analogue regulation and do not flash, if replaced by a functional decoder they have (except a MASSOTH-8FL on the interface of 33666 GEX-coach or GOURMINO)

have fun !

Michael

 

[MRail]

I notice the same effect when videoing city trams.
Digital destination indicators often pulse so as to be illegible.