Originally Posted by: Richard from Chicago 
I understand now that Marklin's Digital transformers only provide track power for locomotives, turnout motors,
and signals. They do not function like the old blue transformers with separate accessory outputs.
If I may challenge this.
The current Marklin
Power supplies are not "digital" !!! , and while they may provide power to a controller (CSx or MSx - who then encode a digital signal to the track/accessories) , they may just as well provide power for lighting.
It is desirable (best practice) not to use the same power supply for both a controller and lighting, but it is absolutely possible.
Quote:So the two choices to power LED's without flickering are (1) Direct DC power, or (2) AC power that has been "rectified" so that it is DC.
Again some cross-communication is creeping in.
The flickering you originally reported was from the track output (which is digigal) and was NOT due to the high frequency used for of the digital signal itself, but due to the slower variable "packets of data" and the spaces between the packets as well as the different behaviours - e.g. mFX decoder responding to a configuration command - which resulted in different amounts of power at a frequency
that the eye can detect.
(As an unrelated comment I find this behavior extremely helpful as it can provide an indication when an mfx detection is occurring )
Connecting a LED to AC (e.g. a good old Blue transformer) would result in a stable 50/60 Hz output that is almost imperceptible to the human eye.
However I would recommend introducing full-wave (bridge) rectification to produce 100/120 Hz. At this frequency you may not even need any smoothing as the eye will not detect it (Read up on the persistence of the human eye)
Todays diodes are quite capable of tolerating a reverse voltage - as long as you have the mandatory current limiting resistor in series.
Quote:The Brawa 94700 model house LED's (req.10-16V) and the Viessmann 6046 model house LED's (req.10-16V) do
have resistors attached to the LED's and yellow and brown wires.
ANY LED
MUST have a current limiting resistor, there is no such thing as a "voltage rating for a LED" (other than the reverse tolerance)
The same LED may be used with different voltage supplies as long as you adjust the resistor accordingly
In summary,
My personal recommendation is to make use of older (good condition) Marklin
transformers (no need for a powersupply) for LED lighting.
The Yellow/Brown offers a fixed brightness, while the Red/Brown offers variable brightness.
And, just to reemphasize, a resistor is mandatory, but once you have a minimim value you may increase it to give a dimmer brightness.
Noted LimitationsPerception of flicker
- Dale - movement either head or object looses the benefit of persistence
- Minox - Camera perception - not the same as an eye
Suggested workaround : add a Capacity
after the rectification - size would be dependent on the load (for LEDs 100uF )
Design practice
- Per - should not "rely" on a LEDs tolerance of revere voltage
Concur with suggestion : Add a normal diode in series (e.g. 1N4001)
Edited by user 22 January 2019 22:45:36(UTC)
| Reason: Noted limitations
