Flicker flicker little LED

[up1950s]

Ok , this is a first for me . I am converting a Bachmann 2-10-2 to a UP one and modifying it to DC . We are just testing the loco without the tender , and all DCC wiring is gone . I replaced the OEM LED with a Golden White . I added a resister to the smokebox PCB , and just ran the chassis pickup from the PCB to the motor . It runs fine in both directions , LED bright forward with a bit of a flicker , but in reverse the LED is off except for flicker .

Question 1 .... Is the motor feeding reverse EMF back to the LED PCB causing this flicker ?

Question 2 ...  Would a full bridge with AC AC across the motor leads and the + and - fed from there to the LED PCB cure this . I guess I will need to put a bridge in the tender also if this is the cure .

Have any of you have knowledge you would like to share , thoughts ?

[Rasputen]

I think Richmond Controls has a diagram somehwere, and they recommend putting another diode
across the LED leads to prevent flickering in reverse.

[Rasputen]

Here is the link - they recommend a diode and an SMD capacitor:

http://www.richmondcontrols.com/Wht_led.doc

[up1950s]

Rasputen , thank you Sir .

[up1950s]

Well given that advice I came up with the work around , and some info .

1 - I was running with a 470 resistor which made the LED more flicker noticeable , increased to 1.5K .

2 - I was testing the loco only , with the tender LED in the circuit it acts like the reverse diode in the schematic I guess and cured the flicker . Thats why I never saw this problem before I guess .

3 - Putting all the components in the schematic in a loco would be very problematic . Why there isn't a single micro LED driver with all the components in a chip for a reasonable price , like a buck or three is surprising . ( DC in LED out )  , though less so with DCC's growth like cancer on steroids .

4 - That Full Bridge idea I had only works if you want the headlite on in both directions , which isn't all that bad in most cases of operation .