Bachmann Lyn Electrics - Lighting Question

[adeshers]

I'm currently renovating a Bachmann Lyn. I've fitted new lamps with 3mm LED's with the idea of directional lighting and it's worked - sort of.
I've got 3mm soft white LED's in the lamps fitted with a diode and resistor and the front one lights going forward and the rear one lights going bunker first
But - when going forwards the rear light shines dimly and vice versa. Can any one of you, more knowledgeable Forumeers, explain this [strike]fnomeenu phernomin[/strike] occurrence.

I've also fitted a Seuthe 6V smoke generator (from Cornwall Boat Models after it being recommended elsewhere on this forum - ain't it great ) with a voltage regulator (a la George Schreyer http://www.girr.org/girr/tips/tips.html )

A few gratuitous pics of progress so far.

 

[C&S]

Really nice to see it coming back from its former state. Like the new chimney and dome. Sorry I can't help with your query, but I know someone who might be able to help (not a forum memeber) if nobody here can assist.

 

[ntpntpntp]

I've got 3mm soft white LED's in the lamps fitted with a diode and resistor and the front one lights going forward and the rear one lights going bunker first But - when going forwards the rear light shines dimly and v.v

How've you wired up the "additional" diode? Is it necessary? I've never needed a 2nd diode when I've fitted directional LED lighting to a DC loco nor a DCC chipped loco.

 

[adeshers]

How've you wired up the "additional" diode? Is it necessary? I've never needed a 2nd diode when I've fitted directional LED lighting to a DC loco nor a DCC chipped loco.

I thought I would need the diode to make sure the LED would only light when going in the right direction but now you've made me think (that's usually asking for trouble 8| ) I've got two diodes together haven't I? as the LED is a Light Emitting DIODE........ ooops.

But would the extra diode cause the LED to light (albeit dimly) when the direction is reversed?

It won't take much to try it out. I'll go do it and report back

 

[Neil Robinson]

I often use an ordinary diode in inverse parallel with a directional lighting led. I notice Aristo seem to do this on their later models.
Even so the opposite direction led seems to flicker a bit on dirty track, I guess there must be some reverse voltage spikes generated by iffy pickup. The ordinary diode in the diagram should protect the led against excessive voltages though.

 

[adeshers]

I've taken the 'superfluous' diode out of circuit and the LED's still work but the fault still persists :thumbdown:

Neil, would your extra diode solve my problem do you think?

 

[Neil Robinson]

I've taken the 'superfluous' diode out of circuit and the LED's still work but the fault still persists :thumbdown:

Neil, would your extra diode solve my problem do you think?

Try it and see, if it doesn't you've still given the leds protection against potentially excessive damaging reverse voltage.

 

[ntpntpntp]

Very curious. Must admit I assumed you'd probably wired the 2nd diode inverse parallel with the LED as Neil says.

How are you powering the loco - track DC, DCC, battery? I'd have thought it must be a rather "dirty" DC supply to get the effect you're describing?

 

[adeshers]

How are you powering the loco - track DC, DCC, battery? I'd have thought it must be a rather "dirty" DC supply to get the effect you're describing?

Track power is from a laptop transformer (20V , 5 amp) through an Aristo Train Engineer (10 amp version). This problem only happens with the Lyn - my Stainz lights operate as you would expect so I don't think it is the power supply.

 

[stockers]

I am no expert but I would have thought a laptop supply was pretty clean - or maybe the laptop/battery do that for it.

 

[adeshers]

Right chaps, after more [strike]playing[/strike] testing the Lyn only has the problem when the TE is set on PWC; on Linear the lights operate correctly (and the momentum feature on the TE seems to operate more 'obviously' when set on Linear so I suppose that's the way to go - problem solved....... I think 8D )

 

[stockers]

Just shows what PWC is doing to those little circuit boards - doesn't it.

 

[Neil Robinson]

Just shows what PWC is doing to those little circuit boards - doesn't it.

That's most likely why Aristo fit inverse parallel diodes to their LEDs as they recommend Pulsed TE output for their locos.

 

[stockers]

They just enjoy blowing up the opposition Neil.