Diary of a 26" x 14" H0e Forest Layout

[mags_minibuilds]

It's been the 3rd day working on this speeder and the chassis is assembled and tested on the layout. I temporarily soldered the motor wires that's why they are hanging out, I will shortened the wires once I do the final assembly and a weight taped on. It creeps nicely, picks up the power from the rails rather well and goes over switches without stalling. I was worried that the coreless motor will not compatible with the PWM controller but it seems to be working. I must say it's been easy and fun to put together this kit because there's not too many pieces and the nickel sheets are so much easier to solder compared to brass.

 

 

[Martijn Meerts]

Looking good. Nickel silver is a breeze when you're used to brass 😄

 

[mags_minibuilds]

Finished soldering all the details except for a couple of details (wipers, door handles, window frame, grill) that I will leave it in nickel color as it looks more natural and eliminates the need for me to paint it with a silver/chrome paint. I will epoxy those details after everything else is painted. It's all in parts again as the chassis got disassembled for painting. Scratched it up a bit and cleaned it with 99% IPA to prep it for priming when the sun comes out.

 

[mags_minibuilds]

Here is the same Speeder I'm currently working on and this person had added working headlights to it. What do you need to install lights inside a locomotive, do you need a circuit board of some sort? Is there a light kit for something like this?
https://aucview.aucfan.com/yahoo/p1095843014/

[Martijn Meerts]

You're rather organised with that plastic box and all. My parts are generally 'somewhere on my workbench' 😄

 

As for the lights, I doubt there's a light kit, but you don't really need a circuit board either. Just a few LEDs, resistors and possible a capacitor and you should be good to go. Which ones exactly depends a bit on how you want to do the lights... 

 

I'm guessing the kits comes with the white lenses at least? In that case you could just glue some small warm white LEDs to the back of the lenses. You can put those in series with a resistor, and connect them to power pickup. You just need to take care of light bleed on the back, but for that you could encase the LED in some epoxy or putty, or even make a small plastic box to encase both LEDs and the resistor.

 

Most my electronics knowledge is stored somewhere in a seldom used section of my brain (for now), so I can't really give a better description or detailed instruction though 🙂

 

[mags_minibuilds]

Thanks @Martijn Meerts for the info! The possibility of adding working headlights is quite intriguing. I saw these micro LED's on Amazon:

https://www.amazon.com/dp/B07P8PMCCS/?coliid=I26E0KCHVAFZO5&colid=4TX0A48422DF&ref_=list_c_wl_lv_ov_lig_dp_it&th=1

 

Will those work or are there any smaller/better options? And are you saying (sorry, I'm not too savvy with the electrical aspect), that if I have 4 LED lights that I only need to use 1 resistor? The resistor itself looks pretty big so I can't imagine it'l fit 4 resistors into that tiny frame.

 

The headlight part is currently a concave brass, I was thinking about drilling a hole in the middle of it and gluing the LED in it.

[Martijn Meerts]

@mags_minibuilds There are smaller options, but then you'll need a microscope to install them. The ones you linked are plenty small, you can easily fit multiple LEDs in one of those lamps 🙂

 

And yes, 1 resistor is enough. Basically, you go from power pickup to resistor to front-left (for example) LED, to front-right LED, then rear-right, rear-left and to the other power pickup. You will have to flip either the front or the rear 2 LEDs around, so that only 2 light up depending on the direction of travel.

 

Something a little like this:

 

 

Someone with more readily available electronics knowledge please correct me if I'm wrong. I have actually recently started getting back into it again a bit, but haven't gotten very far 🙂

 

[mags_minibuilds]

Thanks @Martijn Meerts! I believe I understand what you're saying. I'll have to get some LEDs and try it out.

[cteno4]

Mags,

 

If you need smaller leds I’d look at 0402 leds, 50% smaller than 0603 LEDs. Also I’d just wire a single head light and tail light (in reverse to each other) with the proper resistor and not do two LEDs in series as single led circuits will light up at lower voltages. You’ll need to do a safe drop with single set of reversed LEDs at about 10v for 12v max power so like 500 ohm. If the loco flys off the tracks at 6v then you could assume like a 3v so 150 ohms.

 

https://www.aliexpress.us/item/3256805744126569.html?spm=a2g0o.productlist.main.1.846eRiBjRiBj5H&algo_pvid=acb40b24-3f0b-4055-ba05-8c090cff4848&algo_exp_id=acb40b24-3f0b-4055-ba05-8c090cff4848-0&pdp_npi=4%40dis!USD!3.60!1.26!!!3.60!1.26!%402101fb1117075190582673674e22ab!12000034898029344!sea!US!811587129!&curPageLogUid=y2Arhy7iEqlY&utparam-url=scene%3Asearch|query_from%3A

 

if you want more consistent lighting at all voltages /above around 3 or 4v you can use a current limiting chip. They have tiny ones if these for a buck or so. Basically you just wired the limiter chip in line with the resistors and add a resistor across tow if the chip pins to set the current you want let thru (like around 10ma).

 

jeff

[mags_minibuilds]

@cteno4 Thanks Jeff! I'm a visual person so I'm having a hard time figuring out what you meant by "just wire a single head light and tail light (in reverse to each other)". If I want to have 2 head lights and 2 tail lights, are you suggesting I make two sets of these: 1 head light + 1 tail light + 1 resistor. 

 

I'm using a PWM controller with a 6V wall wort power supply. Is it necessary to have a resistor?

[cteno4]

Yes, that’s it. Just single set of head/tail leds per circuit. Just have to use a higher resistor to make up for the voltage drop of the second set of resistors.

 

jeff

[mags_minibuilds]

@cteno4 I placed an order for the 0402 LEDs and resistors. In the meantime, can you check this out and see if this is the correct way to run the circuit?

 

What ohm resistor will I need for the 2nd circuit? I bought a pack of these resistors:

https://www.temu.com/goods.html?_bg_fs=1&goods_id=601099512343759&parent_order_sn=PO-211-06587809889910396&add_order=1&_x_sessn_id=9z91zrzbb2&refer_page_name=bgt_order_detail&refer_page_id=10045_1707860039192_hskxm3jiiy&refer_page_sn=10045

[cteno4]

Note i rewrote this as i was thinking reversing circuit for bidirectional!

 

Depends on the max voltage you will give the train. That then depends on the motor, test your max speed (ie about to fly off the track) and measure the voltage across the track with a multimeter, or you can just assume 12v as most n scale transformers max out at around 12v.

 

I would look at doing each circuit separately as 2 leds in a circuit may need a bit higher voltage to turn on. plus the white leds have about twice the voltage required to run them at closer to 4v (red leds at 2v or less). You could run a pair red leds in a serial circuit like you show with its own resistor and another circuit with 2 white led with a resistor set for the desired brightness of white leds. even in sereies circuits its best if you can to have all the same type leds when running in the correct current direction.

 

the calculation for the resistor is based on how much voltage the resistor needs to drop. Your red led will drop about 2v and white led closer to 4v. So in the red case you would need to drop the max 12v by 8v (12-4). To calculate the resistance it’s 

 

R = V / I  

 

where R is the resistance of the resistor, V is your voltage drop (9v), and I is your desired current (0.02 A for most LEDs but better to run them like 15ma max to be safe) so for the red

 

R = 8 / 0.015 or about 533 ohms

 

In this case you could easily use the 510 ohm in your set as you probably won’t be running anywhere near 12v. If you measure your max you would run it at you can adjust the calculation. Or also adjust to look right at your usual running speed and just make sure at max running speed/voltage it’s not doing more than 20mA

 

for the white leds the voltage drop would be 2x4v or 8v for the leds and so voltage drop needed by the resistor is 12-8 or 4v so R = 4/0.015 or 267 ohms.

 

I usually run most all LEDs at 10mA max as even at that they are such intense light sources for n scale and can make things glow! You may want to put your led in and test at your normal running mode to adjust resistor to make the led brightness what you want. I use variable resistors a lot for this. You can wire them in to just set the level desired and leave it or measure it and put in a fixed resistor at around that level. One warning though if you use a variable resistor you should either be careful to never turn the resistor all the way down (0 ohms) or you will feed the led too much current and blow it. To be safe a usually wire in a fixed resistor in series with the variable resistor to take the voltage drop to the max of the led current (ie 20ma) so if I turn the variable resistor all the way down I don’t blow the led.

 

you might try mounting the led in the shell, then wire them to the track power while the mechanism is running on the track and see what looks best using different resistors. Start at 500 range and then go up to dim the led. As long as it’s over 500 ohms you are totally safe. If at 500 you want it brighter you then need to see what your max voltage you would run the train at to see if you could go safely below 500 ohm and how far when at max speed.

 

I know this stuff makes folks eyeballs roll back, but once you master that simple equation that links the V, I, and R you’ve mastered a lot of doing very fun things with LEDs! Please yell if you have questions and I can answer them as playing with LEDs I’d really fun!

 

you can get fancy and easily do bidirectional lighting depending on the direction the engine is going. 

 

jeff

[cteno4]

one note the circuit will only work in the forward direction, in reverse none of the circuits will not light. to do that you need to add a bridge rectifier chip to the power feed to provide the same polarity of power regardless of the direction the train is going.

 

these have 4 pins and two are input and two our output. you put the power feed into the input terminals and then on the output terminals the polarity is always the same for your led circuit regardless the polarity of the input from the track (ie forward or reverse). the rectifier chip drops the voltage by about 1v so you can add that into the resistor calculations (ie add one more volt to your led total to see hom much you need to drop the voltage.

 

you can just have one of these rectifier chips attached to your power feed from the chassis then hook up each of your LED circuits to the out put of the rectifier chip, you dont have to wire a separate rectifier chip for each of the led circuits.

 

jeff

[cteno4]

here is the full circuit with rectifier with leds in pairs or all single.

 

for smaller resistors you can also use small smd led resistors to save space. the 1206 are 1/4 watt and plenty for a led circuit and small but still managable. they dont have leads on them but easy to wire up more flexibly than resistors with leads where you have to try and fit in a small space. you can cut up a bit of circuit prototype board to solder stuff to. you can saw up to smaller pieces to fit your need and solder the rectifier and resistors down 

 

jeff 

[mags_minibuilds]

Sorry, I'm slightly more confused, all these electrical technicalities are flying over my head. I came across this video (start at 24:30), how he mounts the 0603 LED SMDs. It seems pretty straight forward to wire front and rear lights and have them work in the direction it's set by reversing the polarity of the wires. Am I missing something here? I drew a circuit diagram to what I think this video is saying...I'm not sure why he used 2 resistors though. That said, the Speeder is super tiny so the least resistors the better.

 

 

 

Edited February 14 by mags_minibuilds

[cteno4]

sorry was trying to explain how this all works. If you want I can just show you a circuit for what you want to do and values of resistors.
 

so what are you looking for a head and tail lights that stay lit going either direction or different lighting depending on direction of the car is going?
 

He is describing is a pair of bidirectional leds where only one is on in the direction of travel.

 

your circuit is not quite right for this. I can draw you the circuits. If you use two different leds (ie red and white) you can use two different resistors to set the brightness of the leds differently or even if the same color leds you can adjust the led brightness differently. 
 

jeff

[cteno4]

here is the simple circuit for say a red and green led. polarity one way the green lights and polarity the other way and the red lights. you can use different value resistors for the red and green as LED voltages differ with color and require a different value resistor to limit the current and set the brightness of the LED.

 

if the leds are the same color (and thus voltage) or if you dont mind a slightly different brightness between different colored LEDs you can use a single resistor as in the second diagram.

 

if you want your lights to stay the same going either direction then you will need a bridge rectifier chip to keep the polarity of your supply power coming from the track the same no matter the direction you have the throttle set.

 

Let me know exactly what you would like for the lighting of your lights on the car and we can get you a circuit that will do that.

 

jeff

[mags_minibuilds]

Thanks Jeff for putting all that effort and time into explaining this!

Okay, that’s where the discrepancy was, all along I was intending the front and rear headlights light up according to the direction of travel, so if going forward the two lights in the front lights up and the rear does not and vice versa. The 4 LEDs are all in the same color so it looks like I only need one resistor. I believe the 2nd diagram is suitable for what I’m looking for!

 

My PWM controller is powered by a 6V wall wort but the Speeder’s max is probably at 4V. I need to test it I get the chassis reassembled.

[cteno4]

Ah ok, now clear. with the bidirectional circuit you don’t need the bridge rectifier chip as you want things to change with polarity change!

 

I wasn’t sure if this little car had headlights in both directions or headlights in one end and tail lights in the other end.
 

Sorry for all the electronics talk, I know it sounds nasty, but once you get the basic concept it then becomes pretty easy to design your own stuff without a full physics course or EE degree.

 

yes then use the single resistor circuit. If white LEDs and your 6v supply max of 2v drop needed so try a 150 ohm resistor for white LEDs and 300 ohm if red.

 

just make 2 of the circuits to get a pair of LEDs for both ends.
 

if you are tight on space you can just solder the fine leads on the LEDs to the ends of a 1206 resistor and wrap in some heat shrink. Will take up less space than a regular resistor with leads.

 

does that help?

 

jeff

[mags_minibuilds]

Hi Jeff, yes, that totally helps, thank you! I'll test it all out once I receive the components. I believe the resistors can be hidden underneath the bench seats.

 

I just now have to figure out what to do with the lens part, since it didn't come with a clear lens I have to make one or find parts. The headlight hole opening is 2mm so either the clear lens from Details West LN-456 which is 2.10mm but I foresee it to be difficult to glue/adhere the lens since it'll only have 0.10mm area to bond. Or this method using fiber optic cable but I'm not sure if the singed end will be consistent in round shape or it doesn't matter?

[cteno4]

you are most welcome! Yes do prototype it all first before trying to mount it into the car. Just hook the circuit to the track while the car is running.

 

Might also play with gallery glass. It’s liquid acrylic to make pho stained glass. They have a clear that made a nice lenses for streetlights I was fiddling with.

 

jeff

[mags_minibuilds]

I tried making beads using Mod Podge Gloss, Aleene's Tacky Glue and Testors Clear Parts Cement & Window Maker. The best outcome was the Mod Podge but I can make indentations by pressing lightly with my fingernails. Does the Gallery Glass dry hard? Other things I can use is UV resin or epoxy but those will turn yellow. I ordered some 2mm fiber optic cable but it might take a month to get here, I'll post my findings when I try it out.

 

Meanwhile, this little Speeder has two color of paint on, will do the last white color on the hood in a couple of days. It's always so nerve wracking to do the masking, I'm either afraid of the paint peeling off when I remove the tape or massive bleed.

[cteno4]

Yes it dries nice and hard and as it sets you can manipulate it some. It’s like a very thick glue. Thick uv curing resin may work as well, some are pretty thick.

 

ill take a look tonight, somewhere I have a big assortment of plastic fiber optics from a sampler. If I can locate it I can pop some in the post to you that should get there pretty quick air mail.

 

painting looks very nice.

 

jeff

[tossedman]

Full cure time for Modge Podge is 4 weeks. 😧