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ChicagoNW
23rd Sep 2011, 06:19 PM
I'm looking for ideas to convert the Bachmann PCC and Brill streetcars to LED lights.

The current design is a grain of rice bulb that sits in a groove in both sides of the body filling metal chassis. The light leaks through the headlight hole. There are no optical conduits to direct the light.

The contacts from the lamp touch and draw electricity from the two sides. The Brill has a light on each end and the PCC only has one at the front.

The chassis fill the bodies and are impossible to solder to. The lighting should be transferable by staying either with the body or chassis. The ideal design will not have any wires.

It would be cool if red tail lights could be added to the PCC.

Any ideas?

Sherman
23rd Sep 2011, 08:00 PM
ChicagoNW,

I'm assuming this is for DC? I've converted a few incandescent headlights to LED for DCC locomotives and the process should be almost the same for DC. The first problem is size. A grain of rice bulb is very small so something like a 1.8mm LED would be closer in size than a "standard" 3mm LED. The second problem is direction- an incandescent bulb projects light in every direction while LEDs concentrate light through the "lens". So if the LED is mounted vertically inline with its leads most of its light will be concentrated upward but I suspect enough will bounce to the side to equal the incandescent lamp.

For the headlight I would take a 1.8mm LED, cut the leads very short (1/8" to 3/16") and solder a 1/4 watt resistor to the anode. Cut one lead of the resistor very short and solder the short lead to the LED. Slip some heat shrink insulation over the solder joints but let the longer resistor lead stick out of the insulation, that will be your electrical pickup for the enginner's side. On the cathode side of the LED you can either leave the lead alone or cut it short and solder a more flexible copper wire to it and use that for your electrical pickup on the fireman's side. Since the LED is a diode it will not be lit when the streetcar is in reverse.

Repeat the process for the rear light but reverse the LED. (Still solder the resistor to the anode but have the anode contact the fireman's side and the cathode on the engineer's side. This will light when the streetcar is in reverse.

If you want the lights to be on at all times (in either direction) you will have to add some circuitry (additional diodes) which you may not have room for. That is an advantage of incandescent lights over LEDs, incandescents don't care which lead is positive and which is ground.

--Sherman

ChicagoNW
24th Sep 2011, 02:43 AM
Here's a look at the space available
http://www.nscale.net/forums/attachment.php?attachmentid=18989&d=1316845510
http://www.nscale.net/forums/attachment.php?attachmentid=18990&d=1316845664
http://www.nscale.net/forums/attachment.php?attachmentid=18991&d=1316845810

Sherman
24th Sep 2011, 10:14 AM
There seems to be much more room at the rear than at the front. The space at the front is pretty tight but I think a 1.8mm LED would fit. At the rear there is probably plenty of room to bend the LED leads 90 degrees to point the lens straight back.

Another option is to purchase pre-wired SMD LEDs. Expensive at $4.00 + delivery for each LED but they are so incredibly tiny that room just wouldn't be an issue. Streamlined Backshop Services sells them on eBay.

Here's a link to a "warm white" pre-wired LED.
http://www.ebay.com/itm/DCC-Parts-1206-SMD-Warm-White-LED-Pre-Wired-38ga-Mag-Wi-/280609521691?pt=Model_RR_Trains&hash=item4155a1801b

And here's a red one.
http://www.ebay.com/itm/DCC-Parts-0603-SMD-Red-LED-Pre-Wired-38ga-Magnet-Wire-/280609517957?pt=Model_RR_Trains&hash=item4155a17185

--Sherman

ChicagoNW
24th Sep 2011, 12:26 PM
In truth there is no room at the back for a stock PCC, such as the "CTA" painted version shown in the other two pictures. The only space not filled by the chassis is the area above the belt-line as seen through the front and rear windows. It is approximately 1.5mm at the top and .1mm at the bottom near the headlight. The metal fills the space inside the body except for the half a millimeter between the two halves of the chassis.

The picture of the chassis are from this body.
http://www.nscale.net/forums/attachment.php?attachmentid=5584&d=1276112215

This is a stock body.
http://www.nscale.net/forums/attachment.php?attachmentid=18993&d=1316878682

How does your system mount?
Is it a direct replacement for the lamp?
Is it attached to the body or chassis?
Does it require machining?

I already own many LEDs from SMDs to 5mmand displays. So supply is not the question. I'm looking for functional design ideas.

If you look closely you'll see the brass through the windows, these streetcars are powered by the overhead lines. If that gives you any ideas. All connections are made by pressure no soldering involved with the chassis.

Sherman
24th Sep 2011, 08:34 PM
What I was thinking is that the pressure of the body shell could hold the LED leads in contact with the frame halves providing the electrical contact. I would imagine that at the very least a small piece of tape would be required to hold the LED in place on the chassis. That way the body shell could be completely removed. If that isn't possible (either the body shell providing pressure, or the frame halves providing electrical contact) then I think some type of wiring would be required or perhaps soldering the LED lead to a piece of brass bent in a 'V' to help provide the contact.

With the pre-wired SMD LEDs the leads are soldered to #38 magnet wire. A small piece of kaptan tape would hold the LED in place and the wire leads could be routed between the frame halves to where ever it is convenient to make electrical contact. Magnet wire could of course be used for the larger 1.8mm LEDs which could be mounted the same way with the leads laying between the frame halves as long as the solder joints are insulated.

I don't have any street cars so I'm mostly basing the mounting ideas on what I've seen in various locos. Usually the hardest part of something like this is figuring out a secure and reliable mounting system, not the details of the electrical work. Even though I have no room for a streetcar track on my current layout I've been tempted by both the Streamlined PCCs and the Brills. The price is certainly right and I like the overall look of the Brill.

--Sherman

ChicagoNW
24th Sep 2011, 09:54 PM
Sherman thank for the ideas

Here's a description

The chassis is the same design used by Bachmann since the 70's — Split frame held apart by plastic washers. The two halves of the chassis tied together by two plastic T-nuts and screws.

The open box motor gets it power from tabs that press against each half of the frame. Worm gears are stuck directly on the armature shaft (longer ones on the PCC).

The light bulb(s) are held between the two halves in a groove (PCC-horizontal, Brill-vertical). The bare wires of the lamp take power from the frame halves.

The older white geared trucks do suffer from split gear syndrome. The current issue with black gears work flawlessly. The black gear trucks retrofit into the older chassis with a little filing of the tabs on the truck.

There are no circuit boards contact strips or wires in the construction. Paying more than $25 for a new one is a bad deal. The new paint schemes are 1000% better than the previous generations.

DCC on the cars is an adventure in machining so very few of these little guys get decoders.

I've been rebuilding these streetcars for almost five years and have way more than a dozen in various states.

If you have streets on your layout you have room for these streetcars. Tomix makes Wide Tram Track with rails embedded right in a ready made street. The minimum curve of 103mm (4in) is easily negotiated by both Bachmanns even though they were design over thirty years apart. The new DCC equipped Peter Witt units can only make it through the 140mm (5.5in) curves. The same with the GE 44 and 70 tonners and most other switchers.

I've tried to find a drawing of the chassis without luck.