Light Bulbs

Hi,

Im currently working on a set of 12 HO Athearn Genesis P40/P42's,

However I am not a fan of the lens inserts for the marker, ditch and headlights since they do not light up realistically with the single internal bulb,

Does anybody know a decent manufacturer that produces or sells bulbs small enough to fit this type of job?

(Walthers-Lifelike grain of wheat bulbs are a bit too large)

Miniatronics bulbs.

http://www.miniatronics.com/Merchant2/merchant.mvc

Below is a link about bulbs in model railroading.

http://www.members.optusnet.com.au/nswm ... in_DCC.htm

Rich

LEDs would actually be a better option. Check out the short video of the full lighting I installed in a VIA Rail P42 under the Lighting section on my site linked at the bottom of this post ....


Mark.

Mark R. wrote:LEDs would actually be a better option. Check out the short video of the full lighting I installed in a VIA Rail P42 under the Lighting section on my site linked at the bottom of this post ....


Mark.

Mark,
BEAUTIFUL WORK!!!
i love the selection feature,

on my layout im running standard DC current, so for me to change the lamps from headlights to markers id be using analog circuitry that will change the light position with the polarity of the power, (i did with an NJT cabcar a while back for its headlight, although the bulb was inside the car and i had ran fiber optic cable from the bulb to the lenses)
what type of LED's did you use and what was the voltage on them???

im assuming id need on solder in a resistor to step down the voltage to levels tolerable for the LED

also are there kits available for projects such as this or is it more of a "treasure quest" for the proper materials, and how hot do the LED's get when running for a decent period of time (lets say a few hours), did you need to insulate them or recess them or were you able to insert them directly into the hole in the body shell without any heat damage to the shell or melting?

Andre - That's the real beauty (or at least one of them) of LEDs - they produce zero heat !

LEDs are quite adaptable for DC purposes as well. A Google search for "LED constant lighting" should turn up a few results. Here's a good one to get you started ....

http://www.pollensoftware.com/railroad/index.html

DCC has been a blessing for those of us who like all kinds of lighting effects, but with a bit of enginuity, some great results for the DC user are also available.


Mark.

Mark R. wrote:Andre - That's the real beauty (or at least one of them) of LEDs - they produce zero heat !

LEDs are quite adaptable for DC purposes as well. A Google search for "LED constant lighting" should turn up a few results. Here's a good one to get you started ....

http://www.pollensoftware.com/railroad/index.html

DCC has been a blessing for those of us who like all kinds of lighting effects, but with a bit of enginuity, some great results for the DC user are also available.


Mark.

as much of a blessing DCC is, i simply avoided it because of the cost to equip all of my locomotives with decoders
but that site is perfect for what im looking for, it has the parts lists too with pricing
however are there LED lamps in the 1 or 2mm size range? (to fit inside the marker and headlight holes on the HO athearn p40/42 )

The number of size variations today is almost mind-numbing ! I've used some LEDs that are small enough to completely mount INSIDE a pedestal mount ditchlight - including the hair thin wires !!! Here's an example of just how small these LEDs are ....



Here's a couple great supliers of minature LED and lighting systems and products ....

http://www.richmondcontrols.com/

http://www.ngineering.com/index.htm


Mark.

The great thing about using LEDs in DC is you dont need any special circuity to make the directional markers work. All you need to do is wire your headlight with the same forward poliarty as the motor going forward and wire your marker LEDs in reverse of that. Since LEDs are diodes the headlight will then only light when your engine is going forward, and the markers only when its going in reverse. This is how almost every HO engine with directional LED headlights is wired.

ApproachMedium wrote:The great thing about using LEDs in DC is you dont need any special circuity to make the directional markers work. All you need to do is wire your headlight with the same forward poliarty as the motor going forward and wire your marker LEDs in reverse of that. Since LEDs are diodes the headlight will then only light when your engine is going forward, and the markers only when its going in reverse. This is how almost every HO engine with directional LED headlights is wired.

i see, so then i wouldnt need the additional diode to ensure the polarity is correct, but i would need to wire the the LED itself to take advantage of this feature, are the LED's contacts labeled or marked for + / - ?

does anybody have photos of this type of work they have done on their own models? id love to take a look at the general layout or even an electrical schematic i can glance at

Yes. The LED Anode is the + and the Cathode is the -. Usually denoted by a small chip in the LEDs rim, a white mark and/or one longer leg of the LED. And no you wouldnt need the additional diodes. You can connect them directly to the track, of course with limiting resistors in the mix also since LEDs dont run on 12v

ApproachMedium wrote:Yes. The LED Anode is the + and the Cathode is the -. Usually denoted by a small chip in the LEDs rim, a white mark and/or one longer leg of the LED. And no you wouldnt need the additional diodes. You can connect them directly to the track, of course with limiting resistors in the mix also since LEDs dont run on 12v

yes thats my ultimate question, whats the voltage of the LED's that would be ideal for an HO layout?

If you're only using analog DC for control and not DCC or any other digital control, you'll want to use the lowest wattage LEDs you can find and a resistor rated for the highest voltage you can get from the tracks, this way the lights won't dim at lower speed. Since LEDs use just barely any power, you could run all the lights off a 9v battery hidden inside the car, this way the brightness wouldn't change or flicker, and even parked engines could still have their marker and cab lights.

The maximum forward voltage for colored LEDs is usually around 1.7 volts. The whites (golden / sunny / warm / blue-whites) are nominally around 3.4 volts.

That being said, white LEDs won't illuminate fully until 3.4 volts is on the rails .... even more with a dropping resistor in series with it. A slick work-around is to install a pair of bridge rectifiers between the trucks and the motor leads and wire the LED across the bridge.

A single diode drops 0.7 volts. Whichever direction the current flows through a bridge, it's going to pass through two diodes (a 1.4 volt drop). A pair of bridges will create a 2.8 volt drop .... enough to sufficiently light a white LED without a resistor.

What this means is that the motor will not see ANY voltage until the 2.8 volt thresh-hold is reached. The LED will never see any more than the 2.8 voltage drop incurred by the diodes in the bride no matter how much higher the track voltage is.

So now, when using your throttle, the 0 to 2.8 volt speed range will do nothing but increase the LED to full brightness .... but no movement - so engines can now sit there with their headlights ON ! Once the throttle is increased above the 2.8 volts, the motor will start to see voltage and it will begin to move.

Here's a link to a couple methods for constant 1.5 volt lighting. The bottom one is basically what I described above ....

http://members.optusnet.com.au/nswmn/con_brill_dc.htm


Mark.