Large Scale Central

USAT F3 build - remote couplers and lighting

I’m working on customizing an F3 while I’m waiting for the snow to melt so I can set up some track. I’ve installed a Airwire Drop-in, Phoenix P8, and battery, and have tapped the data line to the P8 to listen for function packets with an Arduino Pro Mini. I’ll be using the Arduino to drive remote couplers and customize the lighting. The first task was remote couplers.

I found that the proper height for the coupler lands the draft gear box 1/2" below the bottom of the deck. At the front, I was able to squeeze the Kadee 11220 in between the front truck and the pilot, and cut a slot up under the little bumper under the nose door to get it to the proper height. I made an adapter plate from 1/8" aluminum in order to use the holes from the original pedestal. The plate is on 3/16" spacers, and the coupler is on another set of 3/16" spacers, making up the total 1/2". At 3/16" below the deck, the plate is clear of the trucks when they swing, and high enough (close enough to the deck) to stay out of the way of the curved pilot casting. The plate is tapped for 4-40 machine screws to accept the coupler.

The rear coupler was another story. There is not enough room between the rear truck and the back of the unit to fit the 11220 without the coupler sticking way out past the bellows. This wouldn’t look right if I attached another engine or coaches to it. I went around and around, and finally decided to use an 831 gear box and mount a small servo inside the engine to pull the chain to open it. I cut a slot in the deck for the servo horn to stick through. The gear box is mounted as far aft as possible, and secured with two #6 machine screws with nuts, spaced 1/2" from the deck with nylon spacers. One had to be whittled a bit to accommodate the shell of the engine.

Works great!

When I make some progress on the lighting, I’ll post here. I essentially want independent control of the headlight/number boards and classification lights. I’ll be changing the classification lights to white, and converting everything to LED.

awesome!

Looks good. Is the snow ever going to melt where you are?!(http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-cool.gif)

Clever install. Are you using the drop-in’s aux socket to control the front coupler?

Jim Agnew said:
Clever install. Are you using the drop-in’s aux socket to control the front coupler?

I found that the Drop-in sends DCC packets via the orange wire to the P8 at around 10 volts. I spliced in a wire, added a voltage divider to drop it to 5V, and ran it to an Arduino so I can read and respond to the packets. This allows me to intercept function commands sent to the P8 and use them for whatever I want. So I have separate functions controlling the front and rear couplers. I’ll also use this to drive LEDs for the headlight, reverse light, number boards, classification lights, and interior light.

With the Arduino, I could do something like this with F0:

1st press: headlight on
2nd press: headlight off
3rd press: reverse light on
4th press: reverse light off
…and back to the start.

Some progress on the lighting. I built a new board for the front lighting that mimics the shape of the one that came from the factory. I replaced the two headlight incandescent bulbs with doubled up 3 mm warm white LEDs, the number board incandescents with warm white straw hat 5 mm LEDs, and the classification LEDs (red/green from the factory) with the same white ones I used in the headlights, but with a larger resistor to dim them a bit. Each LED has its own resistor, and each group has an NPN transistor to switch it with the microcontroller.

I just have the reverse light and cabin light to go.

I found red/white leds to replace the classification lights. Not completely prototype on the red side, but better than red/green.

I have been thinking of replacing the number board lights with LEDs but afraid I would not get nice dispersion with the lights so close, I want to make a diffuser.

Greg

Greg: I used wide angle straw hat style LEDs for the number boards, and the light is very even (see photo). They work well for interior lighting, too.

Edit: Here’s a close-up photo.

That looks good enough for me, about how far are they from the back of the number boards, and did you use 2 per number board.

Been waiting to convert mine, got 14 to convert… no wait, some are B units… just 5…

Greg

I just used one on each board. If you look at the third photo, three replies up, you can see them. They are just about the same distance as the original incandescents. Maybe 1/4" or so. These are the ones I used: https://www.amazon.com/gp/product/B006S2GBO8

Thanks Eric, nice job and nice results.

Greg

Finished her up this morning. The Arduino is controlling the headlight, number boards, and classificaiton lights. I converted the cabin light to LED, and plugged it into the AUX port on the AW board, and converted the backup light to LED and plugged it in as usual. I now have independent control over the headlight, number boards, classification lights, and cabin light through functions on the throttle, and the backup light comes on when the engine is in reverse (but the headlight stays on if I want it to).

I’ve attached a couple shots from just before I put the shell back on. One is a closeup of the Arudino. Also attached is the function layout I’m using. If I want to add more sounds or lights in the future, I may switch the number boards to always on and/or go to switch on the engine for volume control.

Eric, are you familiar with the “split axle” problem with all USAT trucks? Might be a good time to check them if you have not.

Greg

I’ve seen mention of it, but don’t exactly know what it is. I was in the trucks to remove all the track power pickup parts, and didn’t see anything obviously wrong, but I don’t know what I’m looking for. This unit is a few years old, but was only in Christmas Tree service. I got it on eBay.

I’ll save you some grief, this can happen to new in the box, never used locos.

http://www.elmassian.com/index.php?option=com_content&view=article&id=150&Itemid=167

Greg