Ampacity of PS3 steam upgrade board

Same FET as the PS-2 3V so same rating.  MTH 6V bulbs rated at 60ma.  So go from there.  G

I've seen factory installations with four bulbs on the circuit, and it's fairly common to find three bulbs on a lighting circuit.  That gets you at least 240ma at 6V.

Thanks George & John.  Interestingly, I have a PS2 loco that uses a single bulb for the side-facing(???) PRR marker lights, which bulb draws 100ma.

I hate going to LEDs, because they seem to focus light out the ends.

I use LED's for many lights, but the one place I usually use incandescent lighting is the cab light.  I get a better distribution of the light with those.

If I knew the fet mfr number, I could dig out the datasheet which would list the current capability

John, you work with leds a lot.  Are there any available that cast more light sideways, that would be more useful for marker lights that have light tubes or for boiler lights? 

There are many designs, the 2mm ceramic ones I use for many markers throw a lot of light out the side.  They're the ones you see in many Lionel and MTH markers.  They're not cheap, but they do work well, and they're tiny so they fit almost anywhere.  These are the Lumex 2mm Ceramic Stem Round LED at Digikey.  I occasionally see them cheaper, not long ago I found them at an off-brand place as a lot for about half price, picked  up all they had in red.

Thanks much, John.  Would these be good for firebox door lights, in your opinion?

They are pretty standard 20ma LED's, so you can use them anywhere you use LED's.  MTH and Lionel use these exact LED types for their markers and class lights.  For firebox lights, put a 270 ohm or larger resistor in series for current limiting from the incandescent outputs of the PS/2 or PS32 stacker board.

Thanks, John.   I've ordered some.

https://www.fairchildsemi.com/...mosfets/FDN5630.html

Yep, take the 1.7A with a grain of salt, but a couple hundred MA is not an issue for the lighting circuits.

This may have been the basis for the 2-bulb limit.  The BSH101 FET used in the 5-volt board lights and smoke fan had a 0.7 amp limit.

http://www.datasheets360.com/p...4506618473175455857/

What two bulb limit?  Is that written down somewhere?  I've seen factory installations of PS/2 5V boards with more than two bulbs on a single circuit.

John, I did read it somewhere, possibly in the early editions of the PS2 upgrade kit manuals.

Upgrade kit and was the recommendation, though MTH did use 3 on some production diesels, Int an NB as example.   G