Dimming lights using CVs.

[Potrail2378]

Hi. As per the title, I would like to know if I am able to dim the headlights on my loco's by altering any CV numbers. I usually install 3vDC LEDs with a 1Kohm resistor in series for each LED.

The lights look great on the layout, but are far too bright when being photographed or videoed.

Any help would be much appreciated.

[96RAF]

That would depend upon the loco decoder. Some have the facility, many don’t. You need to check your decoder ‘user manual’.

[Chrissaf]

Dim the LEDs by increasing the value of the resistors. The final value will need to be arrived at through experimentation. Start with a 4.7K resistor value and go up in approx 1K steps to an expected maximum of 10K.

At a guess, I would anticipate a value around 6.8K will give a sufficiently dimmed effect.

As Rob says, very few brands of decoder give the ability to dim LEDs through CV adjustment.

[Fishmanoz]

Chris’s and Rob’s solutions are (semi) permanent but the OP is looking for a temporary one during photography.

Given they are running lights, keeping them synched to direction would be a problem, but what’s the practicality of connecting them to a second CV including a higher value resistor, just for the photography? Turn off Running lights, turn on photo dim.

[Potrail2378]

Hi, and thanks for the answers so far. One particular loco is a Hornby Yeoman class 59 Kenneth J Painter which has a sound decoder fitted. I have put a headlight kit in, which I bought off eBay, but I also installed a headlight below the windscreen which is a bit too bright for the camera.