Passenger car lighting with LED strips, EDIT:photos added

[Lemosteam]

Self-stick aluminum tape for duct work?

[craigolio1]

I thought of that but it's pretty thick.

Craig

[peteski]

I thought of that but it's pretty thick.

Craig

Bare Metal Foil maybe?  It is very thin and pliable. I use it on model automobiles (another one of my hobbies).
http://bare-metal.com/  Available in hobby shops catering to model car crowd.

[craigolio1]

Peteski, that is a great idea.  I too use it on my model cars and there for i happen to have some.  It doesn't come thinner than that.

I sent you a pm (or would it be an email?) about another lighting circuit not related to trains.

Craig

[wdhalsey]

Petski, in your diagram R2 is a resistor to set the brightness of the LEDs.  Would it be possible to replace that with a pot to allow the brightness to be adjustable for different circumstances?

[peteski]

Petski, in your diagram R2 is a resistor to set the brightness of the LEDs.  Would it be possible to replace that with a pot to allow the brightness to be adjustable for different circumstances?

A potentiometer is just a variable resistor, so yes, you sure can replace a fixed-resistance R2 with a pot.  If you are using a 12V LED strip then the R1 will limit the maximum current going through the circuit, even if you adjust the R2 pot to zero ohms.  Going in the other direction (higher resistance) you can make R2 resistance high enough to make the LEDs barely glow.  As for the pot's power raring, that depends on the range of resistance you will be using.  If you are planning on using pot's resistance 15k or higher, then a 1/10W power rated pot will work. But if you use a lower resistance (brighter LEDs), then you should use resistors with a higher power rating (since more current will go through the circuit.  That goes for both R1 and R2 (or a pot as R2). In that scenario a 1/4W R1 and R2-pot should be used.

[wdhalsey]

Peteski, Thank you for the quick reply and confirmation.  I have been looking for a reasonable alternative to the passenger lighting solutions offered by the manufacturers and the after market battery boards.  I think the circuit you designed and publised is an affordable and elegant solution and I appreciate your efforts very much.

[peteski]

Peteski, Thank you for the quick reply and confirmation.  I have been looking for a reasonable alternative to the passenger lighting solutions offered by the manufacturers and the after market battery boards.  I think the circuit you designed and publised is an affordable and elegant solution and I appreciate your efforts very much.

You're very welcome! 

[wdhalsey]

Hi Peteski, I sent you a PM.

[peteski]

Hi Peteski, I sent you a PM.

Got it - will respond soon. 

[craigolio1]

Hey all. It was brought to my attention that my photos of @peteski circuit that I built were no longer accessible. I’m posting a few here to complete the thread.

Here’s the whole thing for size comparison.  Everything is basically mounted around the cap.



Alternate views:







The yellow and black wires are the track bus into tbt rectifier. And the red and black are power out to the LEDs.

I keep one built that I don’t use so I can just keep copying it. Thus far I’ve used this in passenger car lighting, marker lights, to power a flasher circuit for flashing marker lights, and a passenger car drum head. You just need to vary the current limiting resistor.

Craig

[Maletrain]

Craigolio1, would you be so kind as to post a parts list and source for the components you eventually chose to use?  I would like to use those instead of SMDs.

I am thinking I am going to need to use axle wipers for current pickup, since I can't seem to find appropriate trucks for all of the various car types I want to light.  The 3 seconds-before-dark seems to be sufficient to deal with wiper pickups.  And I will just have to provide enough loco units to deal with the drag.

[craigolio1]

Craigolio1, would you be so kind as to post a parts list and source for the components you eventually chose to use?  I would like to use those instead of SMDs.

I am thinking I am going to need to use axle wipers for current pickup, since I can't seem to find appropriate trucks for all of the various car types I want to light.  The 3 seconds-before-dark seems to be sufficient to deal with wiper pickups.  And I will just have to provide enough loco units to deal with the drag.

On page 2, @peteski posted a parts list with digikey part numbers. That’s where I ordered the cape and rectifiers. For the resistors I sized up to 1/8 watt purely for the convenience of assembly and I bought those on eBay.

I use axle wipers and I make my own. I’ll typically use a micro trains pin to hold the truck in and drill out the centre. I then use .010” phosphor bronze and bend two pick ups. They are L shaped. They go up through the hole in the pin. Then I put the wheel sets in and they press up on the pick ups. I cut them a little long over the axle and bend the ends down around the axle. It his creates a bit more contact surface and prevents the wipers from pivoting.

Here you can see the wipers and how they go through the MT pin



Here’s the other side. The two wipers are soldered together and the wire from each truck goes to the rectifier



In this case I used the circuit for a set of marker lights and I tried a variable pot to get the intensity I wanted. The pot and its specs were mentioned earlier in this thread. 



This car is really light weight. It tracks well and the lights are nice and constant.

Craig

Edit: honestly I don’t know why I have an extra resistor under the pot. It’s likely that the pot wasn’t enough so I fortified it. The markers are very dim. You can barely see them in day light so resistance would be very high as far as LEDs go. They only need about 1.5K to keep them from burning up. I routinely use 7-10k on loco ditch lights.

Craig

[peteski]

If the extra resistor is in series with the potentiometer then you added it to prevent burning out of the LEDs if the pot's wiper is accidentally adjusted to zero ohms.

Also, the brighter the LED glows (by using lower value resistor) the shorter time the cap will be able to supply voltage to keep the LED glowing.  But more capacitors can be added in parallel with the original cap to increase the time.

[greenwizard88]

@peteski I used this schematic as a starting point to light some HO scale Athearn shorty passenger cars some years ago, years before I even joined this forum, and it worked out great. Notably, I used a 1000uf capacitor. Thank you for it.