Kato pre-war Budd Observation lighting

[nickelplate759]

I almost have parts for a complete Kato pre-war Budd Observation (the one in the Silver Streak set).    The only thing missing is the lamp to light up the markers and drumhead.   I've looked at the Kato parts page and can't figure out what part to try and get - anyone know?

Plan B is to make something out of spare LEDs, etc., but a factory part would be a LOT easier.   The entire car is a clever puzzle box.

<edit>
Found it!  Brute-force search through the Kato Parts catalog:  #928045
Circuit Board for Observation, 1 ea
N-Scale / Fits: Budd Observation Car (Rear)

Looks like an incandescent bulb!

[peteski]

I would replace that bulb with an LED, resistor, capacitor, and a protection diode (or a bridge rectifier, if it is supposed to be non-directional).  Especially if you run DCC.  Remember the old Kato light boards for passenger cars melting roofs when ran on DCC (the bulbs are powered with full 12V, or more, making them run hot?

[nickelplate759]

Got the board, tested it on DCC (outside of the car) and it does indeed get quite hot.  Time for some surgery.  The electronics is easy, making it fit just right will be a challenge.

[peteski]

Got the board, tested it on DCC (outside of the car) and it does indeed get quite hot.  Time for some surgery.  The electronics is easy, making it fit just right will be a challenge.

You mean fitting the board into the model will be difficult, or fitting the electronics on the circuit board?

[nickelplate759]

Fitting the board with the electronics. 

[nickelplate759]

Got it squeezed in.  LED, rectifier,  resistor, capacitor.

[peteski]

That looks good George (and very small)!   

Actually, with a full bridge rectifier the cap is not needed. It is  only needed when the LED is wired with a diode to work directionally in DC.  Where is the resistor?

Interesting. The way I was thinking would have been to glue the SMD components to the original PC board (after removing the bulb).

[nickelplate759]

The resistor is inside the left shrink insulation im the top photo.  The cap is on the back of the led.   I tried to fit things on the circuit board but there is not enough room in its mounting slot for the rectifier.   Anyway, it works!

[peteski]

The resistor is inside the left shrink insulation im the top photo.  The cap is on the back of the led.   I tried to fit things on the circuit board but there is not enough room in its mounting slot for the rectifier.   Anyway, it works!

Ah, that makes sense. Hard to tell sizes from a photo.  I do have some bridge rectifiers that are much smaller than the one you used. That one would have probably fit on the original board. The important thing is that it fits and works!

[randgust]

Running mine on DC, using the original board, not overheating but if there's a way to toss a capacitor in there to smooth out the flickering I'd be interested in knowing more.

[nickelplate759]

Ah, that makes sense. Hard to tell sizes from a photo.  I do have some bridge rectifiers that are much smaller than the one you used. That one would have probably fit on the original board. The important thing is that it fits and works!

I used what I had handy.  The rectifier is WAY bigger than it needs to be.

[peteski]

Running mine on DC, using the original board, not overheating but if there's a way to toss a capacitor in there to smooth out the flickering I'd be interested in knowing more.

Problem with DC is that it uses a variable voltage, and even at full speed, you probably don't run it at 12V, so it is hard to keep the LED bright. Few years ago I came up with such circuit for Craig's passenger car lights running in DCC.  You could try it in DC, but it might not be as good. The circuit as shown will be the same with a single LED (just install it where the schematic indicates the LED strip).  If you need the LED to be brighter, change the 15K resistor to one with smaller value, but then you might need to also use a larger value capacitor to keep the LED from flickering.  You could try 220, 470, or 1000 uF.