Need help replacing searchlight bulb with 18v LED…

@Mark V. Spadaro posted:

…on 6-19714 New York Central work caboose. All replies appreciated. Thanks.

Try this guy he carries almost everything you could need. :http://www.superlumination.com/trainbulbs.htm

Hmmm, @ThatGuy recommending “this guy”! Thanks.

I'm helping Mark with this car.  The challenge is that the drawing from another OGR thread is not of this car.  The drawing has the spotlight connected with screws.  Mark's appears to be connected with pins. Before I start prying and break something, I wondered if anyone had experience or information on this?

When I type the model number in the Lionel Support site is says, not found.

@Ron045 posted:

I'm helping Mark with this car.  The challenge is that the drawing from another OGR thread is not of this car.  The drawing has the spotlight connected with screws.  Mark's appears to be connected with pins. Before I start prying and break something, I wondered if anyone had experience or information on this?

When I type the model number in the Lionel Support site is says, not found.

Just thinking out loud here but would the yolk need to be spread slightly to release one of the pins? I'm with you, I hate the thought of bending (or breaking) something.

Bob

Ok so the main post is metal.  Hard to break that.  Light off.  I assume the metal post is ground because the frame is metal and the ground wire is attached to the frame.  The positive musy be this metal strip that touches the dimple in the middle of the y post.

Now... How do I get the light out? 

Ron

Oh... Had to destroy the bulb.  But it was dead anyway.  Screw base. 

@Mark V. Spadaro I replaced my 2420 car's lamp with an LED about 5 years ago. I decided not to booger up the lamp housing socket, so I removed the old failed bulb and broke the glass out of it (much as you have already done), and I soldered an LED to the bottom contact of the now defunct lamp base, and the other leg I brought up and hung on the outside of the lamp base where I soldered it - not very pretty on the soldering job, but it works.

I cleaned the contact slider bar on the bottom of the lamp housing assy where the brass pin comes up through the center of the mounting post, to insure as much flicker-free contact as I could. I also cleaned the two mounting pins on the lamp housing to insure a clean electrical ground.

On the bottom of the car, I came off the contact roller with a wire to which I soldered a diode (hidden in the heat shrink in pic below), a capacitor and a current limiting resistor. I would suggest using a 1kohm resistor if you will be running at 18VAC. The capacitor adds greatly to reducing flicker from intermittent roller and wheel contact.

Best o' luck on your project!

George

@GeoPeg  Thanks.  Great info. I started to prepare the base last night for soldering in a new LED and planned to put the resistor underneath the car like you did.  I'll add a cap too.  Great idea.

While searching for the cap I did find these E5 LED's which would essentially make life easier.

Question...  I know LED's don't typically like AC power.  I assume that is what the resistors for.   If I buy the 24v LED version like the one shown, do I still need the resistor if the user is using 18V AC track power?

It's not so much the resistor alone, but a combination with a diode to use an led on AC power. Those bulbs are listed for 24 volts, so would probably work on 18. You would need to know if the rating is for AC or DC to know if a diode is needed.

Edit:

I just checked Amazon listing  and under the description (#2), it states that the bulb base must be positive. To me that means DC.

@John H posted:

It's not so much the resistor alone, but a combination with a diode to use an led on AC power. Those bulbs are listed for 24 volts, so would probably work on 18. You would need to know if the rating is for AC or DC to know if a diode is needed.

Thank John.  They say 24 DC.  So I guess the resistor and diode are a must.

But now another question.  I know sometimes an LED won't light if it does not have enough voltage.  So if they are 24 volt, is that the maximum they can take or what is needed to light?  Wonder if I should just get the 12v since I will be using the resistor and diode anyway.

Ron

I would say that the 24 volt rating is a maximum. It would probably light at 18 volts. A 12 volt light would already have a resistor for the voltage difference ( 3.2 to 12). you would only need to add a resistor for the 6 volts over the 12 volt rating. You would need 750 ohms for 18 volts, and 470 for 12 volts. You would need to add 280 ohms or the closest value above that. I find this link very helpful.