LED headlight for old (DC) Kato SD45

[carmelmodelrr]

I have an old Kato SD45 (DC) which has the original faint, yellow headlight.  Has anyone replaced this light with a bright LED headlight?  If so, where did you get the light?

Thank you in advance.

carmelmodelrr

[jagged ben]

You could google "golden white 3mm LED" you'll get some model railroad vendor options for a dollar or more per LED. (Soundtraxx, TCS).
Or you can search, say, eBay, for "warm white 3mm LED" and get a 100 pack for 10-20 times less per LED that is probably the same thing or very close.  (I advise checking the item location if you don't want it to come dirextly from China.)

Or you can wait for more opinions to be posted here on who suppliesand LED with the very-most-realistic-color-after-comparing-all-the-options-side-by-side for a 2nd generation diesel headlight.  Don't think I don't recommed this. 

Just avoid buying 'white' or 'bright white' as these will likely be more bluish than you want.

[peteski]

You can replace that yellow LED with any 3mm white LED. Depending on what values resistor is used with the yellow LED, you might want to change it too. I suspect the existing resistors value is a bit low.  A 1000 ohm (1k ohm) 1/4W resistor would be recommended.

I buy my parts from industrial suppliers like Digikey or  Mouser Electronics, but many hobby suppliers sell white LEDs.

You should get warm-white LED which emulates a glow of an incandescent light.

N-gineerign has them (scroll down to 3mm warm white LEDs
https://www.ngineering.com/lightng.htm

Richmond Controls has sunny and golden white
https://www.richmondcontrols.com/WhiteLED.html

Miniatronics has these (calls them Yellow Glow)
https://miniatronics.com/collections/leds/products/3mm-leds-5-pcs-yeloglo-white

There are many others out there - this is just a small sample.

You could also buy a light board from Kato which has 3mm warm white LEDs on it, unsolder them from that board and install them in your model.

EDIT:  Like Jagged Ben mentioned make sure to get a warm-white LED.  You could probably find some cheap LEDs on eBay or elsewhere, but you might not like the color.  The suppliers I mentioned above sell warm white LEDs (using fancy names) which were selected to have a proper color appropriate for incandescent locomotive headlights.

[woodone]

I make my own, we are modelers, right?
I use a number drill to size the H//l opening. I use a Sota can for the reflector.  Cut a square out and then polish it up. I polish both sides to make the metal thinner. I then Punch out the reflector and then form it into a concave shape. Then punch a small hole into the reflector and mount a small LED behind the reflector. Use Light activated glue to hold

[peteski]

I make my own, we are modelers, right?
I use a number drill to size the H//l opening. I use a Sota can for the reflector.  Cut a square out and then polish it up. I polish both sides to make the metal thinner. I then Punch out the reflector and then form it into a concave shape. Then punch a small hole into the reflector and mount a small LED behind the reflector. Use Light activated glue to hold

You do  this for N scale models with dual sealed-beam headlight (SD45 in this instance)?!  Each headlight is around 0.040" in diameter.  What diameter hole (drill size) will you drill in that 0.040" diameter aluminum disk?

[GGNInNScale]

Or, you could build up your own light- I use 0201 or 0402 LEDs of various colors, with a 2.2kOhm SMD series resistor.  The 0201s are REALLY hard to work with!!

[carmelmodelrr]

I’ve now installed warm white LEDs in both locomotives—a welcome change. I got the LED’s from a firm in the state of WA:
LighthouseLED’s.com. I’ve dealt with them before and have always been satisfied with their prices — and shipping charges.

Carmelmodelrr

[daniel_leavitt2000]

Don't forget to add a diode when replacing the LED. Newer LEDs are can be damaged by reverse polarity.

[carmelmodelrr]

They sell some LED's with diodes "pre-installed" which are the ones I bought.

carmelmodelrr

[peteski]

They sell some LED's with diodes "pre-installed" which are the ones I bought.

carmelmodelrr

Interesting.  Are you sure it is diodes, not resistors?  I have not seen anybody selling LEDs with reverse voltage protection diodes preinstalled. Resistors, yes.
Do you have link to the actual LEDs you bought?

[carmelmodelrr]

The “pre-wired LEDs” that I bought have resistors, not diodes.  The link is LighthouseLEDS.com, then prewired LEDs.

Carmelmodelrr

[peteski]

The “pre-wired LEDs” that I bought have resistors, not diodes.  The link is LighthouseLEDS.com, then prewired LEDs.

Carmelmodelrr

I found them.  Yes, the resistor is built into the LED housing.  In this configuration you can't add a protection diode Daniel was suggesting.  Hopefully those LEDs will not be affected by BEMF voltage spikes from the motor.  You still might see dim flicker of the LED on the rear of the model's travel direction. Usually adding a capacitor across the LED cures that, but because the resistor is inside the LED, that is also not an option.  Since it works for you, no need to worry about it.

[brill27mcb]

Sorry, but I'm not understanding this. With DC operation, couldn't the protection diode simply be in series with the LED and its resistor, and in the same polarity orientation as the LED?

Rich K.

[peteski]

Sorry, but I'm not understanding this. With DC operation, couldn't the protection diode simply be in series with the LED and its resistor, and in the same polarity orientation as the LED?

Rich K.

You are correct. It can be in series if its reverse leakage current is less than the maximum reverse current of the LED (which is related to the reverse voltage). That diode will also reduce the voltage by 0.7V which in the great scheme of things is not all that much.



My favorite is example  A.  Minimal component count as each forward biased (illuminated) LED's voltage drop limits the reverse voltage (and current) of the dark  LED to  a safe level.

But the other examples are also perfectly safe to use.  In the above circuits (when used) D1 is that protection diode and C1 eliminates the sight flicker of the headlight on the opposite side of loco's travel..

[brill27mcb]

Thanks! I appreciate the diagrams, with the call-outs of the component specifications. They are very helpful.

Rich K.