DCC DDC Flickering Lights Problem

[D1054]

Dear All,

I have a DCC lighting query which I need help with if poss.

I'm reducing cab lighting voltage using CV55 and CV56, but when I reduce the values to the levels I really want for the cabs, the lights are caused to flicker. However, if I apply the same/similar low voltage across the lighting circuit through a standard variable DC power supply (speed controller), I don't get flicker. This suggests it's something in the output from the DCC Lenz controller at lower voltage output settings which is causing the flicker.

Anyone got any ideas how this problem could be addressed?

Cheers!

 

[D1054]

The dark side has suggested that the decoder dimming process is by switching the current on and off rather than controlling the output voltage (rather like the speed controller), and the flicker is due to the switching rate reducing to a level which doesn't defeat the eye.

They suggest using resistors to effect the dimming.... I'll give it a try.

 

[richard carr]

You need to tell us what kind of decoder you are using please.

For example on an ESU Loksound CVs 55 and 56 are 2 of the motor control CVs

Richard

 

[mickoo]

The dark side has suggested that the decoder dimming process is by switching the current on and off rather than controlling the output voltage (rather like the speed controller), and the flicker is due to the switching rate reducing to a level which doesn't defeat the eye.

They suggest using resistors to effect the dimming.... I'll give it a try.

A resistor will certainly help, just place in series with the lamp and set the light control to maximum and then adjust the resistor size until you get the right light level.


Another option is to add a capacitor to the circuit, that'll act as a mini stay alive for the lamp, sort of a smoothing choke or micro battery, it should also reduce the flicker, place the capacitor across the lamp circuit so that it is in parallel to the load, no idea what size but start with something small like 1000uF or so and see how you go. Is the lighting LED or filament lamp, the LED will flicker more as it's instant on and off, normal lamps have some residual heat that keeps the filament hot and thus lit between the pulses but if the pulses are slowed down they too will begin to flicker.

 

[D1054]

You need to tell us what kind of decoder you are using please.

For example on an ESU Loksound CVs 55 and 56 are 2 of the motor control CVs

Richard

Hi Richard,

I'm using Lenz Silver decoders. CV's 55 and 56 control outputs to A and B directional lights.

Cheers, Boris.

 

[D1054]

A resistor will certainly help, just place in series with the lamp and set the light control to maximum and then adjust the resistor size until you get the right light level.


Another option is to add a capacitor to the circuit, that'll act as a mini stay alive for the lamp, sort of a smoothing choke or micro battery, it should also reduce the flicker, place the capacitor across the lamp circuit so that it is in parallel to the load, no idea what size but start with something small like 1000uF or so and see how you go. Is the lighting LED or filament lamp, the LED will flicker more as it's instant on and off, normal lamps have some residual heat that keeps the filament hot and thus lit between the pulses but if the pulses are slowed down they too will begin to flicker.

Thanks for this - I'm running with the resistor option for now, but will look into the small capacitor option if no joy.

Cheers, Boris.

 

[Yorkshire Dave]

Hi and apologies if you've already tried these.....

Having looked at the Lenz Silver/Gold decoder manual I would have a look at not only CVs 56 and 57 but 55, 61 and 62 as these also relate to lighting functions.

One other item I would check is to make sure CV 29 has not accidentally been set for 14 or 27 speeds steps (running notches) as this can cause the lights to flicker when 28 or 128 speed step operation has been selected on the handset.

David

 

[richard carr]

Hi Richard,

I'm using Lenz Silver decoders. CV's 55 and 56 control outputs to A and B directional lights.

Cheers, Boris.

Sorry Boris I can't help a lot as I don't know a thing about Lenz decoders.

I do know though that you might need a resistor to trim the brightness but you shouldn't need anything to stop it flickering other than to adjust the CV settings, some of which will be designed to make your lights flash.



Richard

 

[D1054]

Hi and apologies if you've already tried these.....

Having looked at the Lenz Silver/Gold decoder manual I would have a look at not only CVs 56 and 57 but 55, 61 and 62 as these also relate to lighting functions.

One other item I would check is to make sure CV 29 has not accidentally been set for 14 or 27 speeds steps (running notches) as this can cause the lights to flicker when 28 or 128 speed step operation has been selected on the handset.

David

Dave, thanks for this. I think this is exactly what happened. When I switched to 14 speed steps - all ok, but returned to on-off, on-off on each step if on 28 or 128. Happy enough with 14, but only as it's controlling the fans speed and cab lights.....